Research ArticleTransition Metal Complexes of Mixed Bioligands SynthesisCharacterization DFT Modeling and Applications
Mohamed S A Abdel-Mottaleb 1 and Eman H Ismail2
1Nano-Photochemistry Solarchemistry and Computational Chemistry Labs Chemistry Department Faculty of ScienceAin Shams University Abbassia 11566 Cairo Egypt2Analytical and Inorganic Chemistry Labs Chemistry Department Faculty of Science Ain Shams University Abbassia11566 Cairo Egypt
Correspondence should be addressed to Mohamed S A Abdel-Mottaleb phochem08photoenergyorg
Received 3 April 2019 Accepted 28 April 2019 Published 23 May 2019
Academic Editor Hassan Arida
Copyright copy 2019 Mohamed S A Abdel-Mottaleb and Eman H Ismail (is is an open access article distributed under theCreative CommonsAttribution License which permits unrestricted use distribution and reproduction in anymedium providedthe original work is properly cited
Divalent transition metal complexes [MGlu-Arg (H2O)]H2O and [MGlu-Arg (H2O)]H2O where MCo Ni Cu and ZnGlu glutamic acid and Arg L-arginine are prepared and characterized using different techniques DFT and TD-DFTmodelling validated and interpreted some experimental results Weight loss technique reveals efficient corrosion inhibitionaction of these complexes towards aluminum metal at different temperatures Our results point to corrosion inhibition throughchemical adsorption on the aluminum surface Additionally a facile calcination of Co and Cu complexes at 550degC yields nanosizedoxides of Co3O4 CoO and CuO crystalline phases (e complexes show remarkable biological activities towards pathogenicbacteria and fungi Moreover in vitro anticancer activity evaluation of these complexes is achieved against hepatocellularcarcinoma (HepG-2)(e results are correlated withmolecular descriptors such as chemical potential and hardness obtained fromthe frontier orbitals
1 Introduction
(e chemistry of amino acid coordination compounds hasalways been an intriguing challenge to the inorganicchemists (is class of molecules have been foundthroughout the life science and vary tremendously in theirfunction and complexity(ese compounds play an essentialpart of metabolism and cellular signaling and as a part ofdrugs and as hydrogen storage media [1]
Many transition metals with mixed amino acid com-plexes revealed their biological activity which place themin several biochemical processes [2ndash5] (e ternary com-plex models provide information about how biologicalsystems achieve their specificity and stability as well asstrategies to improve these features for biotechnologicalapplications [6]
Glutamic acid (Glu) (2-Aminoglutamic) is one of the 20most common natural amino acids which is considered to
be one of the building blocks in protein synthesis [7ndash9] It isof interest for brainmemory and biochemistry and as an-ticancer drug by reducing its toxicity against normal cells[10] Glutamic acid has three potential coordination sitesthe amino nitrogen and two carboxylic groups and theelectronegativity of the N and O atoms as well as the flexibleskeleton of the glutamic facilitate its coordination behavioras bidentate or tridentate ligand [11]
Arginine is an essential amino acid that is physiologicallyactive in the L-form L-arginine appears as a zwitter ion witha protonated guanidine group in aqueous solutions aspontaneous process resulting in a thermodynamicallydurable form in both solutions and crystals (e presence ofa guanidine group in L-arginine enhanced the interestingbehavior of antimicrobial activity against bacteria and fungi[12] (e coordination mood for a copper complex withamino acids like L-arginine and glutamic acid is bound by anamino nitrogen and a carboxyl oxygen [13]
HindawiJournal of ChemistryVolume 2019 Article ID 3241061 18 pageshttpsdoiorg10115520193241061
We focus here on the preparation and characterization ofthis class of mixed amino acid complexes of four divalenttransition metal ions of Co Ni Cu and Zn
Modelling using DFT theory and TD-DFT will be in-vestigated in an attempt to validate and characterize structuraland electronic properties of M(II) Glu-Arg complexes inaqueous solution (is will shed light on the nature of M-Linteraction Such knowledge is likely to provide some help inthe rational design of new complexes of biological impor-tance Additionally cytotoxicity will be evaluated In-vestigation of the biological activities include g-negative (Paeruginosa and E coli) pathogenic bacteria and g-positive(Streptococcus p and Bacillis sub) pathogenic bacteria
It is known that amino acids act as an eco-friendly in-hibitor for several metals as copper aluminum steel andnickel L-arginine and its zinc complex are used as nontoxicand low-cost corrosion inhibitors for carbon steel [14ndash16](us we will undertake corrosion inhibition abilities studiesof the complexes prepared towards aluminum because theyare widely exploited in automobile aerospace and house-hold industries
Additionally the metal complexes could be consideredas a precursor for thermal preparation of nanosized metaloxides (us we will investigate calcinating the complexesunder investigations to check the possibility of obtainingmetal nano-oxides in a facile way for possible application asphotocatalysts
2 Experimental
21 Materials and Preparation of the Complexes All chem-icals were purchased from Sigma-Aldrich Glutamic acid(CAS Number 56-86-0) and L-arginine (CAS Number 74-79-3) ligands as well as metal carbonates CoCO3middot3Co(OH)2(CAS Number 12602-23-2) NiCO3middot2Ni(OH)2middot4H2O (CASNumber 12607-70-4) CuCO3middotCu(OH)2middotH2O (CAS Num-ber 12069-69-1) and 2ZnCO3middot3Zn(OH)2 (CAS Number5263-02-5) were used without further purifications
[M(II)(Glu)(Arg)] complexes were synthesized followingthe method used in [16] Refluxing equal-molar amounts ofM(II)carbonate (1mmol powder) and water-soluble glutamicacid (1mmol) L-arginine (1mmol) in sim100ml bidistilledwater at about 80ndash363K for 2ndash3 days gives dense precipitateupon scratching (e obtained dense precipitate was filtratedand washed with absolute ethanol Crystallization of the newternary complexes was achieved in absolute ethanolbidistilled water mixed solvent Unfortunately no singlecrystals could be obtained
22 Instrumentation (e contents of C H and N weredetermined by Vario El Elementar while metal percentageswere determined by atomic absorption spectrometry (Per-kinElmer AAs 3100) FTIR spectra of the ligands and thecomplexes in KBr discs were recorded on a Jasco FTIR-300ESpectrometer (400ndash4000 cmminus1 range) microanalytical labo-ratory in the central laboratory of Ain Shams University
Mass spectra were recorded at 350Cdeg and 70 eV onShimadzu GCMS-QP5050A spectrometer and ESR
spectrum of the Cu complex was recorded at room tem-perature using a Bruker ESR-spectrometer model EMX at9706GHz (X-band) using 22-diphenylpyridylhydrazone(DPPH) as standard (g 20037)
Conductivity measurements of 10minus3M aqueous solu-tions (de-ionized water) at 25degC were carried out usingWTW D-812 Weilheim conductivity meter model LBRfitted with a cell model LTA 100
23 +ermogravimetric Analysis (ermogravimetric analy-sis (TGA) of metal complexes was carried out starting fromroom temperature sim303K to 1273K under nitrogen atmo-sphere at a heating rate 283Kmiddotminminus1 using TA instrumentmodel SDT600 Mass spec ESR and TGA analysis were donein National Research Center lab Cairo (e UV-Vis spectrawere recorded in aqueous solutions (10minus2M) at room tem-perature with typical ranges from 800 to 190 nm on Cary 100which is done in the microanalytical laboratory in the centrallaboratory of Ain Shams University
24 Nanosized Metal Oxide Preparation (e metal com-plexes were calcined at 550degC for 6 h and the metal oxidesobtained were characterized by X-ray diffraction scanningelectron microscopy and transmission electron microscopyXRD analysis showed that the obtained oxides are crystallineand corresponded to the Co3O4 CoO and CuO phasesCrystal size and shape were determined by SEM
25 Magnetic Susceptibilities Magnetic susceptibilities weremeasured at room temperature by the Gouy method using amagnetic susceptibility balance JohnsonMatthey Alfa productsmodel MKI Diamagnetic corrections were calculated fromPASCALrsquos constants Mercury tetrakis-thiocyanatocobaltatewas used as a standard (e analysis was carried out in mi-croanalytical laboratory Cairo University
26 Corrosion Inhibition Materials and Methods A purealuminum foil sheet (Al) of 9892 purity which is press-cutto form specimens with dimensions of 1 cmtimes
1 cmtimes 015 cm was usedOne liter of 1M HCl solution was prepared using
deionized water Al samples were immersed for 7 hours in20ml of 1M HCl used as corrosive solution An electronicweighing balance (Easyway-JA 1003A) micrometer heatingmantle and a water bath were used Various concentrations(10minus2ndash10minus5M) of mixed ligands (glutamic acid + arginine bythe ratio 1 1) and their ternary metal complexes wereprepared and dissolved in 1M HCl and examined as in-hibitors for Al corrosion by weight loss method (e mixedratio (1 1) of these two ligands was the same ratio as thatused in preparation of the four metal complexes Before eachrun the surface of Al was polished with different grades ofemery papers degreased with ethyl alcohol washed thor-oughly with double distilled water dried in air and finallyweighed (en these specimens were immersed in 20mlinhibited and uninhibited 1M HCl solution in open con-tainers for 7 h for aluminum specimens as immersion time
2 Journal of Chemistry
then they were withdrawn from the test solution washedwith deionized water and acetone dried and reweighed(econtainer was placed in a water bath maintained at (303plusmn 1)K (e experiments were operated without (blank) and withthe various concentrations of the mixed ligands and thecomplexes separately (e weight loss was taken as thedifference in weight of the specimen before and after theimmersion time (e experiments were carried out in waterbath with temperature range 293ndash313plusmn 1K
27 Biological Activity (e antimicrobial activity of theprepared ternary metal complexes against two gram-positivebacteria (Streptococcus pneumoniae Bacillis subtilis) twogram-negative bacteria (Pseudomonas aeruginosa Escherichiacoli) and four fungi (Aspergillus fumigates Syncephalastrumracemosum Geotricum candidum Candida albicans) wereinvestigated by a Regional Center for Mycology and Bio-technology (RCMB) Al-Azhar University Cairo
28 Cytotoxicity Cytotoxicity evaluation using viabilityassays was performed by a Regional Center for Mycology ampBiotechnology (RCMB) Al-Azhar University Cairo (einhibitory activity of ternary metal complexes is screenedagainst the cell line hepatocellular carcinoma (HepG-2)
29 Computational Methods Density functional theory(DFT) and its time-dependent extension (TD-DFT) theoryemploying BP86D3DEF2-SVP model and auxiliary basisDEF2JK were carried out using Orca 4012 package [17]Our calculation utilizes the atom-pairwise dispersioncorrection with the BeckendashJohnson damping scheme(D3BJ) [18 19] RI approximation [20] was used Overlap-fitted RIJCOSX approximation was also utilized as a speed-up option leading to enhanced speedups [21 22] withalmost no loss of accuracy [23] First we ran a geometryoptimization and frequency job using BP86D3DEF2-SVP)and auxiliary basis def2J [18 19] All frequency modes arereal indicating that the equilibrium geometry is reachedWe used the same model for EPR simulations of thedoublet state In the case of UV-Vis computations weutilized different models including CAM-B3LYP functionalwithout returning a satisfactory result matching the ex-perimental results (e most successful one that producedresult in excellent agreement with the experiment wasBP86D3DEF2-SVP [18ndash20] and utilizing def2J auxiliarybasis We utilized SMD solvation model [24] Spartan 16parallel package (httpswwwwavefuncom) has beenused to obtain the potential energy surfaces (PESs) at theωB97X-D6-31G(D) level of the DFT
A Broadberry workstation (40 cores) (UK) and a MacPro (12 core) workstation were used
3 Results and Discussion
31 Structure and Spectroscopic Properties Elemental ana-lyses (C H N and metal) and physical and chemicalproperties of the prepared ternary complexes are given in
Table 1 where (1) [ComiddotGlumiddotArgmiddot(H2O)2]middot05H2O (2)[NimiddotGlumiddotArgmiddot(H2O)2]middot05H2O (3) [CumiddotGlumiddotArg]middotH2O and(4) [ZnmiddotGlumiddotArgmiddot(H2O)2]middotH2O
(e thermal decomposition of these complexes in therange (511ndash603K) indicates thermal stability (e effer-vescence test with sodium carbonate confirmed that all theprepared complexes are containing free acidic proton (emagnetic moments molecular weight (Mol wt) and molarconductivity values are given in Table 1 (e pH valuesindicate slightly acidic character (e obtained experimentaland theoretical data confirm the suggested structures shownin Figures 1 and 2
(e paucity of information about mixed amino acids(glutamic acid and arginine) metal complexes motivated usto investigate their molecular structures using DFT theory tocharacterize structural and electronic properties consideringCo(II) and Cu(II) Glu-Arg complexes in aqueous solution asrepresentative of all complexes Optimized geometries aredepicted in Figure 1 Such knowledge is likely to providesome help in the rational design of new complexes for theirbiological importance
In this pH range glutamic acid and L-arginine arepredominantly present in their zwitter ion form and eachhas two coordination sites (one N and one COOminus) which areagreed with their distribution coefficients [24] (e analysisand optimized geometry computations suggested that Nithe important vibrational frequencies of arginine glutamicacid and their ternary metal complexes bands (II) andZn(II) complexes are of distorted octahedral structuresimilar to Co(II) complexes Based on 10Dq values of theseternary complexes the distorted octahedral structure issuggested for nickel cobalt and zinc complexes and squareplanar for copper complex Moderate conductivity mea-sured confirms the existence of intramolecular hydrogenbonds Also magnetic moments of the synthesized com-plexes have been measured in order to confirm theirstructures (e data are presented in Table 1
311 IR Spectra (e important vibrational wavenumbers ofarginine glutamic and their ternary metal complexes bandsare listed in Tables 2 and 3 Arginine showed bands at 1698and 1409 cmminus1 assigned for asymmetric and symmetricstretching vibrations of the carboxylate moiety It also showedmedium broadband at 3086 cmminus1 which attributed to theamino NH2 group (e IR spectra of the complexes did notshow any free carboxylic beaks due to strong intramolecularhydrogen bonding Also IR spectra of the four complexesexhibit crowded region between 3500 and 3000 cmndash1 whereH2O ndashOH and ndashNH stretching modes are expected to ab-sorb (e broadband in the range 3300ndash3400 cmndash1 could beattributed to the intramolecular hydrogen bonding(O HndashO O HndashN OndashH N) An example of the IRspectrum is given in Figure 1S Similarly glutamic acid IRspectra (Figure 3S) showed two bands at 1641 1418 and3062 cmminus1 as reported before [25 26]
Upon complexation the NH stretching wavenumber isshifted to 3141ndash3184 cmminus1 indicating that the amino ni-trogen groups are coordinated to the metal atom [27]
Journal of Chemistry 3
Figure 1 (e optimized structure of Co(II) and Cu(II) complexes (dotted lines represent H bonding) indicating the coordination sites ofthe ligands which result in the most stable orientation Ni and Zn complexes have geometries similar to Co complexes
Figure 2 Optimized geometry around the central transition metal ions showing different bond lengths and angle
Table 2 Experimentally and theoretically simulated IR spectra (in cmminus1) of the studied complexes Assignment of experimentally measuredIR key modes
(e C-NH2 stretching bands of the guanidyl group ofalpha amino group have shifted from 1242 to 1175 cmminus1 ofglutamic acid and L-arginine with respect into (1122ndash1131)cmminus1 of the prepared metal complexes In opposite situationarginine has been shown to have two bands observed at 1586and 1608 cmminus1 due to the asymmetrical vibrations of theC-NH2 bonds of the guanidino group which is protonatedto give the guanidinium form without a significant change incase of complexation [28]
(e asymmetrical (υCOOasy) and symmetrical(υCOOsy) carboxylic groups are shifted in the preparedcomplexes to higher or lower values than their values inligands case as shown in Tables 2 and 3 and also thedifference between these bands are more than 200 cmminus1 inall the prepared metal complexes which indicated that thedeprotonated carboxylic groups in both ligands act asmono dentate groups
All the prepared complexes exhibited bands in the rangeof 3340ndash3472 cmminus1 of υ(OH) signifying that H2O moleculesexist in these complexes [29 30]
(e new confirmed bands only appear in the fourprepared complexes at 538ndash572 cmminus1 and 412ndash456 cmminus1which are assigned to υ(M-O) and υ(M-N) stretching bandsrespectively [31]
(e optimized geometry of the complexes shows dis-torted overall octahedral (or better the square pyramidalC4v-local symmetry of Co(II) ion) for the Co(II) complexand the slightly distorted square planar coordination of theCu(II) ion in the Cu(II) complex Ni and Zn complexes areof similar geometry to the Co complexes Figure 3 shows thatthe local symmetry of both centrosymmetric cations isnoticeably distorted with different M(II)-O and M(II)-Nbond lengths and bond angles indicated in Figure 2
(e simulated PES maps [32] which shed light on thebinding sites of the complexes are depicted in Figure 3Inspection of Figure 3 shows that Co(II) complex exhibits
larger positive potentials (299 kJmol) than Cu(II) complexwhich bears enhanced negative potential than that on Co(II)complex (the difference between negative and positive po-tential energy limits (Delta) PES 24 and minus9 kJmol forCo(II) and Cu(II) complexes respectively) (us Cu(II)complex could act as nucleophile whereas Co(II) complex isof enhanced electrophilic nature during interactions
312 Mass Spectra (e mass spectra of the four complexeswere recorded and provided good evidence and confirma-tion of the molecular weight of these complexes (molecularion peaks (MIPs) are detected under severe experimentalconditions [16] which results in of splitting of crystallinewater) (Figure 2S shows the mass spectrum of Zn(II)complex as example)
313 UV-Vis Absorption Spectra Figure 4 shows the the-oretical and experimental UV-Vis spectra of Co(II) andCu(II) as examples (e results confirm that 1 2 and 4complexes have almost tetragonal distorted octahedralstructure (C4v-local symmetry) with different distortiondegrees which is obvious from the wavenumber and 10Dqvalues of the complexes compared to their literature values[33] Cu complex exhibits slightly distorted square planarshape Table 4 shows electronic spectral data and ligand fieldparameters such asDq B (free ion) B (complex) and β usingband-fitting equation [34 35]
(e value of Racah parameter B (free ion) is larger thanthat of B (complex) due to the covalence bonding of thecomplex (e value of β (nephelauxetic ratio)lt 1 is calcu-lated according to equation (1) βlt 1 validating octahedralgeometry [34 35]
β B(free ion)
B(complex) (1)
Table 3 Experimentally and theoretically simulated IR spectra (in cmminus1) of the studied complexes Assignment of theoretically calculated IRkey modes for Co(II) and Cu(II) complexes in the gas phase Excellent match between experimentally determined and theoreticallycomputed IR modes in case of Ni and Zn complexes is obtained
Complex υ (OH) υ (COO) υ (M-O) υ (M-N)
[Co(glu)(arg)(H2O)2]middotH2O2513 (H-bonded H2O and O of COO of Gu) 16848 (Ar) 5543 46363521 1740 (Gu)
Spectral data and assignments are summarized inTable 4
10Dq for the nickel complex was determined by twoprocedures [34]
(e first one is by solving equations (2) and (3) using theenergy terms of the different triplet states transitions sup-plied for Ni(II) [34] as shown in Table 4
(en applying the trial and error procedure a value for∆ that fits in equations (2) and (3) was found to be10935 cmminus1 which suggested the octahedral structure (esecond method for calculating 10Dq used Tanabe andSugano diagrams for the different metal ion complexesFrom Ni(II) diagram we could be able to deduce the ex-pected positions of the (3A2g⟶ 3T2g) and the(3A2g⟶ 3T1g) transitions (is method corresponds to a
pure crystal field approach and assumes that the value ofthe free ion Racah parameter (B) is maintained in thecomplex
Applying this procedure and considering the ratio of ]1]2 1582225641 062 the best vertical line which fulfilsthis ratio cuts the ∆B axis at a value of 139 and Bcomplexis calculated by equation (4) We found the value765273 cmminus1
299
ndash275
299
ndash275
(a)
272
ndash272
272
ndash272
(b)
Figure 3 PES maps (a) Co complex (upper pan solid surfaces and lower pan clipped surfaces) and legend color codes given in kJmol(b) Cu complex (upper pan solid surfaces and lower pan clipped surfaces)
(4) mdash mdash 221 ]1 45249 Charge transfer mdash mdash
Tetragonal distortionpseudosquarepyramidal
(distorted octahedral)
Journal of Chemistry 7
Bcomplex 2v21 + v22 minus 3v1v2( 1113857
15v2 minus 27v1( 1113857 (4)
(en 10Dq 10637253 cmminus1 is compared to the value of10935 cmminus1 obtained by the first method and both valuesconfirm octahedral structure [34] (e magnetic moment ofthe nickel complex was 31 which also confirmed octahedralstructure [16]
Racah parameters for Co(II) complex is also calculatedsimilarly
Furthermore Co(II) complexes have the effectivemagnetic moment μeff 413 (is value is higher than spinonly moment for three unpaired electrons 389 due to aconsiderable orbital contribution [34 36]
(e Zn complex did not show any d-d transitions butdisplayed charge transfer bands as shown in Table 4 (eexistence of charge transfer was due to transition betweentwo different principle quantum numbers from three to fouras distorted tetrahedron being completed by two watermolecules and forms zinc octahedral complex [34ndash37]
(e longest wavelength weak peaks are observed at516 nm (ε middotM 206 Lmiddotmolminus1middotcmminus1) and 636 nm (ε middotM
179 Lmiddotmolminus1middot cmminus1) for Co(II) and Cu(II) complexes re-spectively (e use of TD-DFT at BP86 DEF2-SVP andauxiliary basis DEF2JK level in water (using SMD solvationmodel) [24] results in λmax Co 5291 nm (oscillatorstrength f 0003) and λmax Cu 6486 nm (f 00256)which are in excellent agreement with the experimentalresults
(e computed natural transition orbitals of the longestwavelength transitions in both complexes reveal the largest(greater than 82) contribution of beta HOMO-LUMOwith minor (about 108) contribution of alpha HOMO-LUMO in case of Co(II) complex and about 992 con-tribution from the beta-HOMO-LUMO in case of Cu(II)complex MOs involved in the electronic transitions aredepicted in Figure 5 which illustrate clear dxz or dyz(e)⟶ dz2 (a1) transition in the local square pyramidal(C4v) of Co(II) ion in the Co(II) complex Metaldxy(b2g)minus dx2 minusy2(b1g) transition is dominant in case oflocal square planar symmetry of the Cu(II) complex (is isapproved by low molar absorptivity experimentally ob-served in the UV-Vis spectra of both complexes andsupported by low value of the computed oscillatorstrengths of the forbidden d-d transitions which acquiresome allowness due to geometry distortion of bothcomplexes
314 ESR Spectra For elucidation of the geometry of thecopper ternary complex ESR measurement gives veryuseful information about the stereo chemistry bondingbetween copper and ligands Figure 1S shows the ESRspectrum of the copper complex with a comparativeadvantage and axial symmetry (g || (parallel) 210748g (perpendicular) 201232 (204984) (ese valuesconfirm square planar coordination in which g || gt g gt 2so the unpaired electron found in the dx2 minus y2 orbital andthe ground state is 2B1g [38] (e observed and calculated
g values are different from ge 20023 due to spin-orbitcoupling (e computed g components are not equalreflecting anisotropic effect and the value of g changes as afunction of the orientation of the molecule relative to theexternal magnetic field (is value is close to the spin onlyvalue and it is in a fair agreement with the computed electronspin only value of ge(computed) 20498 [38] Co(II) com-plex is characterized by g 21280 (e simulated EPRspectrum of Co(II) complex returns ge value of 21085
Different values of Mulliken spin density are shown inFigure 4S in such metal-chelates point to purely anisotropiccouplings (e unpaired electron is totally localized onCo(II) ion In case of Cu(II)-complex electron spin pop-ulation is more distributed with about 46 on the Cu(II)ion(is may result in the simulated significant HF couplingin the case of chelating atoms around Cu(II) ion (e datapoint to mixed copper-nitrogen and copper-oxygen bondsin agreement with the computed optimized geometry [38]
32 +ermal Analysis (ermogravimetric analysis (TGA)for the all prepared ternary metal complexes was carried outin nitrogen atmosphere (e thermal decomposition of thefour complexes displayed similar patterns as their ligands
It is well known that amino acids exist only in solid stateso their thermal decomposition has been endothermal be-tween minus72 and minus151 kJmol when heating in range between185degC and 280degC (eir thermal decomposition releasesthree gases mainly H2O less NH3 and hardly any CO2TGA gives the weight of these gases as weight loss calcu-lations which evolve in appreciable amount [39]
Also the thermal decomposition of L-arginine-dopedKDP potassium dihydrogen phosphate crystal started to loseweight with temperature from 341K to 393K releasedammonia and water molecules gases [40]
(e amino acids are totally broken within the range603ndash793K as shown in Figure 6 and Table 5 (e first stepsare weight loss of the three gases H2O NH3 and CO2 withintemperature range about sim423ndash623K (e hydrocarbonsmatter loses weight in the temperature range sim350ndash520degC(e residues for these complexes are mixture with differentratios of metal and metal oxide above temperature range643ndash793K
It is noteworthy to mention that the geometries of thestudied complexes are similar to L-arginine metal complexreported before [41] which have been confirmed by X-raycrystallographic data of single crystals
33 Nanosized Metal Oxides Characterization
331 XRD of Nano CuO and Nano Cobaltosic Oxide(Co3O4) XRD of thermal synthesized copper oxide nano-particles starting from copper glutamic arginine-mixed li-gands complex gives characteristic peaks at 2θ 326deg 356deg387deg 489deg 536deg 582deg 616deg 663deg and 681deg for the markedindices of (110) (002) (111) (202) (020) (202) (113) (022)and (113) respectively as shown in Figure 7(a) which iscomparable with the literature values (e average primaryparticle size of the copper(II) oxide nanoparticles was
8 Journal of Chemistry
TG (m
g)
80
60
40
20
DTG
(mgmiddot
min
ndash1)
000
ndash020
ndash040
ndash060
ndash080
Weight loss ndash1925mgndash24174
Weight loss ndash1745mgndash21914
Weight loss ndash1366mgndash17154
Weight loss ndash0710mgndash8916
Weight loss ndash0276mgndash3466
273 473 673 873 1073 1273Temperature (K)
(a)
273 473 673 873 1073 1273Temperature (K)
TG (m
g)
100
50
DTG
(mgmiddot
min
ndash1)
000
ndash020
ndash040
ndash060
Weight loss ndash1890mgndash14111 Weight loss ndash8641mg
ndash64514
(b)
Figure 6 Continued
Alpha HOMO Alpha LUMO
Beta HOMO Beta LUMO
(a)
Alpha HOMO Alpha LUMO
Beta HOMO Beta LUMO
(b)
Figure 5 Frontier MOs of (a) Co(II) complex and (b) Cu(II) complex involved in the longest wavelength electronic transition Surfacessimilar to that of Co complex are obtained in case of Ni (ere are no d-d transitions in Zn complexes
Journal of Chemistry 9
Table 5 (ermogravimetric analysis decomposition data for the metal ternary complexes
Complexes Mol (wt) TG range (degC) Mass loss () found (calculated) Total mass loss () Assignment
Figure 6 TG and DTG of (a) [Co(glu)(arg)(H2O)2]middot05H2O (b) [Ni(glu)(arg)(H2O)2]middot05H2O (c) [Cu(glu)((arg)]middotH2O and(d) [ZnmiddotGlumiddotArgmiddot(H2O)2]middotH2O
10 Journal of Chemistry
estimated using well-known DebyendashScherrer formula usingthe full width at half maximum (FWHM) of the (111) peaksin the XRD K(α) is the wavelength of X-ray source(15406 A 015406 nm) β∆θ is the full width at halfmaximum (FWHM 01378) and θ 387 is the diffractionangle corresponding to the lattice plane (111) which gives Dsim143ndash204plusmn 08 nm patterns [42ndash44]
(e pattern of XRD for cobalt oxide nanoparticles showscharacteristic peaks at 2θ values at 1898deg 3127deg 3682deg3848deg 4478deg 5568deg 5934deg 6521deg and 7731deg which arecorresponding to their indices (111) (220) (311) (400) (511)and (440) in agreement with JCPDS Card No 76ndash1802 (ispattern confirms the phase formation of cobalt oxidenanoparticle Figure 7(b) (e average size of the Co3O4particles was calculated by the DebyendashScherrer equationDK(α) λ(β cos θ) whereD is the average crystalline size λ isthe wavelength of CuKα θ is Braggrsquos angle and β is the fullwidth at half maximum (FWHM) of the diffraction peak (eaverage dimension D is sim147ndash182plusmn 06 nm at 2θ 3682degwhich is the intense peak [44]
332 EDX of Nano CuO (e synthesized nano copperoxide is confirmed by the EDX spectrum and SEM imagemeasurement shown in Figure 8 which confirms the highestformation percent of CuO and traces of copper carbide (eSEM image for nano copper oxide CuO shows a mixingnanosize 270sim1079 nm [42 43]
333 EDX of Nano Cobaltosic Oxide (e synthesized nanocobalt oxide is confirmed by the EDX spectrum measure-ment shown in Figure 9 which confirms the highest for-mation percent of cobaltosic oxide Co3O4 and traces ofcobalt carbide (e SEM image for nano cobaltosic oxideCo3O4 shows a mixing nanosize 318ndash8543 nm
34 Applications
341 Biological Activity Mixed ligand ternary complexeshave been examined for their in vitro antimicrobial activity(is investigation was performed using the diffusion agartechnique (Figure 5S) (e assays collection included
g-negative (Pseudomonas aeruginosa RCMB 010043 andEscherichia coli RCMB 010052) pathogenic bacteria usingGentamicin 5mgml as a reference compound and g-pos-itive (Streptococcus pneumoniae RCMB 010010 and Bacillissubtilis RCMB 010067) pathogenic bacteria using Ampi-cillin 5mgml as a reference compound It was also in-cluded four fungi (Aspergillus fumigatus RCMB 02568Syncephalastrum racemosum RCMB 05922 Geotrichumcandidum RCMB 05097 and Candida albicans RCMB05036) using Amphotericin B 5mgml as a referencecompound [30 45]
(e inhibitory effects of the used ligands and theirternary polymer complexes against the used organisms aregiven in Table 6 In general the used ligands did not displayantifungal or antibacterial inhibitory
For antifungal assay examination and based on theminimum inhibitory concentration (MIC) values it is foundthat the inhibitory effect of all the ternary complexes varyfrom moderate to weak against Amphotericin B controlexcept in the case of Candida albicans (RCMB 05036) whichis not affected by both cobalt and zinc complexes
(e antibacterial activities of the obtained ternarycomplexes are determined in terms of MIC values As shownin Table 6 all complexes display moderate activities againstStreptococcus pneumonia (RCMB 010010) and Bacillis sub-tilis RCMB 010067 (e growth of the gram-negative bac-teria Pseudomonas aeruginosa RCMB 010043 andEscherichia coli RCMB 010052 is extremely affected by bothcopper and nickel complexes which display strong inhibitionagainst the gram-negative pathogenic bacteria with MICvalue less than the Gentamicin control (e remainingcomplexes do not display the same behavior during theassay
342 Cytotoxicity One of the fundamental goals in me-dicinal chemistry is the development of new anticancer andantimicrobial therapeutic agents Cancer treatment usingmetal-based drugs is one of the very effective strategies as themetal ions are capable of binding to nucleic acids stereo-specifically with varying strength
In vitro anticancer activity evaluation of the newlysynthesized compounds was carried out against human
Cou
nts
400
300
200
100
010 20 30 40
Angles (deg2θ)50 60 70
(a)
Cou
nts
100
50
010 20 30 40
Angles (deg2θ)50 60 70
(b)
Figure 7 XRD pattern of (a) copper oxide CuO and (b) cobalt oxide Co3O4 prepared by thermal decomposition at 550Cdeg starting frommetal glutamic arginine mixed ligands complex
Journal of Chemistry 11
cancer cell lines hepatocellular carcinoma (HePG2) becauseliver cancer is the third most common cause of death incancer using MTT method [26 46 47]
Doxorubicin HCl is one of the most effective anti-cancer agents is used as a reference drug in this study (eobtained results from Table 2S indicated that most of thesemoleculesrsquo behavior can be observed from the values of the
half maximal inhibitory concentration IC50 whichfor glutamic and arginine are 167 and 376 μgmlrespectively
IC50 results indicate that the ternary complexes havepromised inhibition of HePG2 liver tumors [48 49]
Cell viability was assessed by themitochondrial-dependentreduction of yellow MTT (3-(45-dimethylthiazol-2-yl)-25-
108K096K084K072K060K048K036K024K012K000K
000 100 200 300 400 500 600 700 800 900
Cu Kβ
Cu Kα
Cu L
O KC K
(a) (b)
Figure 8 EDX and SEM images of CuO obtained by thermal decomposition at 550Cdeg starting from copper glutamic arginine mixed ligandscomplex
135K120K105K090K075K060K045K030K015K000K
000 100 200 300 400 500 600 700 800 900
O K
Co L Co Kα
Co Kβ
(a) (b)
Figure 9 EDX and SEM images of Co3O4 obtained by thermal decomposition at 550Cdeg starting from cobalt glutamic arginine mixedligands complex
Table 6 Antimicrobial activity of prepared ternary metal complexes
Sample tested microorganisms Glutamicacid L-arginine (1) (2) (3) (4) Standard
lowastNA no activity Values in bracket are the MIC values
12 Journal of Chemistry
diphenyl tetrazolium bromide) to insoluble purple formazan[45] (e prepared ternary metal complexes are of differentviability percentages as depicted in Figure 10 Data of bothligands are also included for comparison
Table 2S shows that the ligands have lower inhibition ofHePG2 than their metal ternary complexes (e coppercomplex introduces the highest inhibition
Additionally Table 7 summarizes some computedelectrical reactivity [50] and thermodynamic propertiesfor Co(II) and Cu(II) complexes (as maximum andminimum IC50 of the four prepared ternary metalscomplexes) which are correlated with the inhibition ofhuman cancer cells and are useful to explain the roleplayed by molecular properties in inhibition of humancancer cells
(e simulated data summarized in Table 7 conclude thefollowing
(i) Cu complex is more energetically stable relative toCo complex by about minus265 kJmol
(ii) Cu complex is characterized by lower dipole mo-ment and lower polarizability relative to Co(II)complexes
(iii) Enthalpy and Gibbs free energy of the Cu complexesare more stable by about minus265 kJmol relative toCo(II) complex Lower entropy reflects lower degreeof randomness of Cu(II) complex
(iv) (e chemical potential (μprime) (negative of molecularelectronegativity) of Cu(II) complex is much higherthan that of Co(II) complex reflecting the enhancedreactivity of Cu(II) complex as nucleophile becauseμprime measures the escaping tendency of electrons fromthe complex (μprime (LUMO+HOMO)2) [50]
(v) Cu complex is characterized by lower hardness thanCo(II) complex Hardness measures the resistanceto electron transfer (η (LUMO-HOMO)2) [50]
It seems that more thermodynamically stable and lesspolar Cu complex exhibits that enhanced responsive elec-tron cloud transfer to the surrounding tumor relative to theCo(II) complex (ese quantitative molecular descriptors[50] explain the promising inhibition activity of the Cu(II)complex (e results are correlated with the above-discussedPES results which show that Cu complex could act asnucleophile whereas Co complex is of enhanced electro-philic nature
(e nucleophilicity of Cu complex (seeking for positivelycharged sites of the reactant) together with its electricalthermodynamic and molecular properties favors its prom-ising inhibition activity towards HePG2 cancer cell [51ndash53]
343 Corrosion Inhibition of Aluminum An assessment ofcorrosion rates and inhibition efficiency for aluminum withdifferent inhibitor concentrations were computed as followscorrosion rate Rcorr was computed using equation (5)
Rcorr M1 minusM2( 1113857(mg)
A cm2( ) times t(h) (5)
where M1 weight (g) before immersion M2 weight (g)after immersion A area (cm2) of the specimen andt exposure time (h)
(e inhibition efficiency (IE) was evaluated usingequation (6)
IE Rblank minusRinh
Rblank1113890 1113891 times 100 (6)
120
60
100
80
60
40
20
00 10 20 30 40 50
GlutamicLarginineCu(II)
Ni(II)Co(II)Zn(II)
Figure 10 Cell viability of (HePG2) at different concentrations of ligands and the prepared metal complexes
Table 7 Simulated electrical properties of complexes studied exhibiting enhanced inhibition of HePG2
where Rblank corrosion rates in the absence of inhibitor andRinh corrosion rates in the presence of inhibitor [16]
Table 8 shows the calculated corrosion rates and inhibitionefficiencies of aluminum specimens in aqueous solution of 1MHCl as the corrosive medium in absence and presence ofmixed ligands and their ternary metal complexes at differenttemperatures (293 ndash313) K for 7 hours of each concentrationFigure 6S shows that as the concentration of ligands and theircomplexes increases Rcorr decreases and IE increases formixed ligands and their metal complexes acted as more ef-ficient inhibitors than their mixed ligands alone
344 Adsorption Isotherms and the +ermodynamic Acti-vation Parameters (e metal surface coverage degree(θIE100) was subjected to different adsorption iso-therms (e well fit for weight loss data is obtained forLangmuir adsorption isotherm Figure 11
Table 8 Corrosion parameters for aluminum in aqueous solution of 1M HCl in the absence and presence of different concentrations ofmixed ligands and their metal complexes at different temperatures for 7 hrs
Inhibitors C (times10minus2M)Corrosion rate times10minus4
Figure 11 Langmuir adsorption isotherms of the mixed ligands(L) and their metal complexes
14 Journal of Chemistry
(e temperature effect (293ndash313 K) on aluminum weightloss inhibition may be attributed to two main mechanismsphysical and chemical adsorption [37] (e suggested mech-anisms are obtained as the temperature increases the efficiencydecreases for mixed ligands but increases for their metalcomplexes depending on the nature of bond formation be-tween the mixed ligands and aluminum surface which isdifferent from the nature of bond formation between metalcomplexes and the aluminum surface [16] Arrhenius equation(7) gives the relation between the corrosion rate andtemperature
lnRcorr lnAminusElowast
RT (7)
where A is the Arrhenius factor Elowast is the apparent activationenergy of the corrosion process R is the rate gas constant andT is the absolute temperature (e straight line slope oflogRcorr vs 1T for aluminum 1M HCl at 4times10minus4molL after7 h is minusElowast2303R for the inhibitors (Figure 12)
(e activation thermodynamic parameters for alumi-num dissolution could be obtained from the transition stateequation (8)
lnRcorr
T1113874 1113875 ln
R
Nh1113874 1113875 +
ΔSlowast
R1113888 1113889minus
ΔHlowast
RT1113888 1113889 (8)
where the entropy of activation ∆Slowast and the apparent en-thalpy of activation ∆Hlowast can be obtained from the intercept
3150
02
04
06
logR
corr
(gmiddoth
ndash1middotcm
ndash1)
08
1
12
32 325 331000T(Kndash1)
335 34 345
BlankMix ligandsZn2+
Co2+Ni2+Cu2+
Figure 12 Arrhenius of log corrosion rate (Rcorr) vs 1T for aluminum in 1M HCl without and with 004times10minus2MLminus1 of inhibitors (mixedligands and their metal complexes)
Table 9 (ermodynamic parameters for the adsorption of (004times10minus2)ML mixed ligands and their metal complexes on aluminum metalin aqueous solution of 1M HCl at different temperatures for 7 hrs
and the slope for the straight line of the relation betweenln(RcorrT) vs (1T) respectively N is Avogadrorsquos numberand h is Planckrsquos constant (e Gibbs free energy of acti-vation ∆Glowast can be detected by equation (9)
ΔGlowast ΔHlowast minusTΔSlowast (9)
Table 9 shows the thermodynamic parameters for theadsorption of mixed ligands and their metal complexes (epositive value of ∆Hlowast indicated the endothermic property ofdissolution process nature for aluminum in the acidicmedium [54]
However the blank ΔHlowast value is higher than the in-hibitor metal complexes which indicated that the inhibitionefficiency generally increases with increasing temperature(e association step is the rate-determining step rather thana dissociation process in presence of the metal complexesinhibitors due to the negative values of ΔSlowast It is known thatthe values of ΔGlowast above 40 kJmiddotmolminus1 are referred to chargetransfer from the inhibitor molecules into aluminum surfaceto form coordinated compound on the Al surface whichblocks it against corrosion process by different degrees Alsothe chemical adsorption process mechanism is confirmed bythe values of ΔGlowast above 40 kJmiddotmolminus1 [16 54ndash56]
4 Conclusions
Novel coordination materials of ternary divalent metalions (Cu(II) Ni(II) Co(II) and Zn(II)) chelated by thebidentate glutamic acid (Glu) and L-arginine (Arg) aminoacids are synthesized and characterized (e metal ionscomplexes are modelled using density DFT and TD-DFTtheory Computed molecular and spectroscopic (IR UV-Vis and EPR) properties validated the experimental re-sults (e used computational methods are capable ofproviding good structural descriptions for the TM com-plexes Consistent with the experimental properties theoptimized structures of the complexes [Cu(II) Glu-Arg]and [Co(II) Glu-Arg (H2O)2] reveal that symmetry en-vironment of Cu(II) exhibits slightly distorted squareplanar shape whereas Co(II)-complex has a distortedoctahedral (where Co(II) central ion is of C4v-localsymmetry) Spectral properties of [Ni(II) Glu-Arg(H2O)2] and [ZnmiddotGlumiddotArgmiddot(H2O)2] complexes indicatethat they have similar structure as Co(II) complex All thestudied ternary metal complexes are of different anti-fungal activities ranging from moderate to weak withoutpractically noticed inhibitory effects whereas antibacte-rial activities of all studied metal complexes show sig-nificant effects
Cytotoxicity studies against (HePG2) reveal the prom-ising potentiality of Cu(II) complex as inhibitor of cancercells(e results are correlated with the computed moleculardescriptors including dipole moment polarizability ther-modynamics and reactivity properties as well as the PESmaps
(e corrosion inhibition of aluminum metal specimensin 1M HCl is efficiently achieved by mixed ligands and theirmetal complexes studied
Data Availability
(e data used to support the findings of this study areavailable from the corresponding author upon request
Conflicts of Interest
(e authors declare that they have no conflicts of interest
Supplementary Materials
(e supplementary materials consist of six figures and twotables to further clarify the structures and trends of the newlyprepared metal ternary complexes (SupplementaryMaterials)
References
[1] Z Ozturk D A Kose A Asan et al ldquoPorous metal-organicCu(II) complex of L-Arginine 2synthesis characterizationhydrogen storage properties and molecular simulation cal-culationsrdquo Hittite Journal of Science and Engineering vol 1no 1 pp 1ndash5 2014
[2] S A Lahsasni R A Ammar M F Amin et al ldquoMixed-ligandcomplex formation of Cu(II) with 12- diphenylethylenedi-amine as primary ligand and amino acids as secondary li-gandsrdquo International Journal of Electrochemical Sciencevol 7 pp 7699ndash7711 2012
[3] H Sigel B P Operschall S S Massoud B Song andR Griesser ldquoEvidence for intramolecular aromatic-ringstacking in the physiological pH range of the mono-deprotonated xanthine residue in mixed-ligand complexescontaining xanthosinate 5prime-monophosphate (XMP)rdquo DaltonTransactions vol 46 no 46 pp 5521ndash5529 2006
[4] S Udhayakumar K G Shankar S Sowndarya S VenkateshC Muralidharan and C Rose ldquol-Arginine intercedes bio-crosslinking of a collagen-chitosan 3D-hybrid scaffold fortissue engineering and regeneration in silico in vitro and invivo studiesrdquo RSC Advances vol 7 no 40 pp 25070ndash250882017
[5] P K Datta M Chandra and A K Dey ldquoTernary complexesof copper(II) nickel(II) and zinc(II) with nitrilotriacetic acidas a primary ligand and some phenolic acids as secondaryligandsrdquo Transition Metal Chemistry vol 5 no 1ndash3 1980
[6] J S Woertink L Tian D Maiti et al ldquoSpectroscopic andcomputational studies of an end-on bound superoxo-Cu(II)complex geometric and electronic factors that determine theground staterdquo Inorganic Chemistry vol 49 no 20pp 9450ndash9459 2010
[7] S Dutta S Ray K Nagarajan et al ldquoGlutamic acid analoguesused as potent anticancer a reviewrdquo Der Pharma Chemicavol 3 no 2 pp 263ndash272 2011
[8] T Sismanoglu S Pura and A Bastug ldquoBinary and ternarymetal complexes of Congo red with amino acidsrdquo Dyes andPigments vol 70 no 2 pp 136ndash142 2006
[9] R N Patel H C Pandey K B Pandeya et al ldquoMixed ligandcomplex formation of nickel(II)copper(II) and zinc(II) withsome amino acids and imidazolesrdquo Indian Journal ofChemistry-Section A Inorganic Physical +eoretical andAnalytical Chemistry vol 38 no 8 pp 850ndash853 1999
[10] L Meng and Z Lin ldquoComplexations of alkalialkaline earthmetal cations with gaseous glutamic acidrdquo Computational and+eoretical Chemistry vol 1039 pp 1ndash10 2014
16 Journal of Chemistry
[11] L D Pinto P A L Puppin V M Behring O C AlvesN A Rey and J Felcman ldquoSolution and solid state study ofcopper(II) ternary complexes containing amino acids of in-terest for brain biochemistry-2 homocysteine with aspartateglutamate or methioninerdquo Inorganica Chimica Acta vol 386pp 60ndash67 2012
[12] A Wojciechowska A Ggor and W Zierkiewicz ldquoChiraloctahedral complexes of Co(III) as catalysts for asymmetricepoxidation of chalcones under phase transfer conditionsrdquoRSC Advances vol 5 no 46 pp 36295ndash36306 2015
[13] B M Weckhuysen A A Verberckmoes L Fu andR A Schoonheydt ldquoZeolite-encapsulated copper(II) aminoacid complexes synthesis spectroscopy and catalysisrdquo Journalof Physical Chemistry vol 100 no 22 pp 9456ndash9461 1996
[14] K Y El-Baradie N A El-Wakiel and H A El-GhamryldquoSynthesis characterization and corrosion inhibition in acidmedium ofl-histidine Schiff base complexesrdquo Applied Or-ganometallic Chemistry vol 29 no 3 pp 117ndash125 2015
[15] S S R Anthony and R Susai ldquoInhibition of corrosion ofcarbon steel in well water by arginine-Zn2+ systemrdquo Journal ofElectrochemical Science and Engineering vol 2 no 2pp 91ndash104 2012
[16] E H Isamil F F AlBlewi N Soliman and M M H Khalilldquo(ermal studies and mass loss inhibition for some newmixed amino acid metal complexes with their applicationsrdquoJournal of +ermal Analysis and Calorimetry vol 125 no 1pp 289ndash300 2016
[17] F Neese ldquo(e ORCA program system 4012rdquo Wiley In-terdisciplinary Reviews Computational Molecular Sciencevol 2 no 1 pp 73ndash78 2012
[18] S Grimme S Ehrlich and L Goerigk ldquoEffect of the dampingfunction in dispersion corrected density functional theoryrdquoJournal of Computational Chemistry vol 32 no 7pp 1456ndash1465 2011
[19] S Grimme J Antony S Ehrlich and H Krieg ldquoA consistentand accurate ab initio parametrization of density functionaldispersion correction (DFT-D) for the 94 elements H-Purdquo+e Journal of Chemical Physics vol 132 no 15 article154104 2010
[20] F Weigend ldquoHartree-Fock exchange fitting basis sets for H toRnrdquo Journal of Computational Chemistry vol 29 no 2pp 167ndash175 2008
[21] F Neese F Wennmohs and A Hansen ldquoEfficient ap-proximate and parallel Hartree-Fock and hybrid DFT cal-culations A lsquochain-of-spheresrsquo algorithm for the Hartree-Fock exchangerdquo Chemical Physics vol 356 no 1ndash3pp 98ndash109 2009
[22] R Izsak and F Neese ldquoAn overlap fitted chain of spheresexchange methodrdquo Journal of Chemical Physics vol 135no 14 article 144105 2011
[23] T Petrenko S Kossmann and F Neese ldquoEfficient time-dependent density functional theory approximations forhybrid density functionals analytical gradients and paralle-lizationrdquo Journal of Chemical Physics vol 134 no 5 article054116 2011
[24] A V Marenich C J Cramer and D G Truhlar ldquoUniversalsolvation model based on solute electron density and on acontinuum model of the solvent defined by the bulk dielectricconstant and atomic surface tensionsrdquo Journal of PhysicalChemistry B vol 113 no 18 pp 6378ndash96 2009
[25] S Donovan C Stiefbold and K Sprague ldquoChapter 3Chemical properties of amino acids and identification ofunknown amino acidsrdquo in Proceedings of the 17 thWorkshopConference of the Association for Biology
Laboratory Education (ABLE) vol 17 pp 35ndash70 Bain-bridge GA USA March 1996
[26] C C Wagner J Enrique and C Claudia ldquoVibrational andmagnetic properties of a CuMg glutamate complexrdquoArgentina Acta Farm Bonaerense vol 22 no 2 pp 137ndash1422003
[27] M Arif R Sur and M Arshad ldquoStudies on the thermaldecomposition of copper (II) flouride complexes with variousamino acids in nitrogen atmosphererdquo Turkish Journal ofChemistry vol 25 pp 73ndash79 2001
[28] A Ghosh M J Tucker and R M Hochstrasser ldquoIdentifi-cation of arginine residues in peptides by 2d-IR echo spec-troscopyrdquo Journal of Physical Chemistry A vol 115 no 34pp 9731ndash9738 2011
[29] K Nakamoto Infrared Spectra of Inorganic and CoordinationCompounds Part B Wiley-Interscience New York NY USA5th edition 1997
[30] E Santi M H Torre E Kremer S B Etcheverry andE J Baran ldquoVibrational spectra of the copper(II) and nick-el(II) complexes of piroxicamrdquo Vibrational Spectroscopyvol 5 no 3 pp 285ndash293 1993
[31] H N Aliyu and A S Mohammed ldquoSynthesis spectropho-tometric and biological activity of nickel (II) and copper (II)complexes with schiff base derived from acetylacetone andhistidinerdquo Global Advanced Research Journal of Microbiologyvol 1 no 5 pp 67ndash71 2012
[32] J S Murray and P Politzer ldquo(e electrostatic potential anoverviewrdquo Wiley Interdisciplinary Reviews ComputationalMolecular Science vol 1 no 2 pp 153ndash163 2011
[33] E R Souaya M M H Khalil and E H Ismail ldquoSynthesis andcharacterization of ternary complexes of certain hydroxylacids and their biological applicationsrdquo Research Journal ofPharmaceutical Biological and Chemical Sciences vol 5 no 4pp 18ndash30 2014
[34] N N Greenwood and A Earnshaw A Review of Chemistry ofthe Elements Pergamon Press Oxford UK 1984
[35] V Reddy N Patil and S D Angadi ldquoSynthesis character-ization and antimicrobial activity of Cu(II) Co(II) and Ni(II)complexes with ON and S Donor ligandsrdquo E-Journal ofChemistry vol 5 no 3 pp 577ndash583 2008
[36] F A Cotton G Wilkinson C A Murillo et al Advances inSchiff Base Chemistry Wiley New York NY USA 6th edi-tion 1999
[37] M M H Khalil E H Ismail S A Azim and E R SouayaldquoSynthesis characterization and thermal analysis of ternarycomplexes of nitrilotriacetic acid and alanine or phenylala-nine with some transition metalsrdquo Journal of +ermalAnalysis and Calorimetry vol 101 no 1 pp 129ndash135 2010
[38] F Mabbs and D Colisson Electron Paramagnetic Resonanceof D Transition Metal Compounds Vol 102 ElsevierAmsterdam Netherlands 1992
[39] M M H Khalil E R Souaya E H Ismail et al ldquoTernarytransition metal complexes of nitrilotriacetic acid and valineor leucine synthesis and biological applicationsrdquo ChineseJournal of Inorganic Chemistry vol 29 no 9 pp 1969ndash19782013
[40] I M Weiss C Muth R Drumm and H O K Kirchnerldquo(ermal decomposition of the amino acids glycine cysteineaspartic acid asparagine glutamic acid glutamine arginineand histidinerdquo BMC Biophysics vol 11 no 1 2018
[41] A M Petrosyan V V Ghazaryan G Giester and M FleckldquoSulfamates and methanesulfonates of L-arginine and L-his-tidinerdquo Journal of Molecular Structure vol 1163 pp 114ndash1272018
Journal of Chemistry 17
[42] T Kavitha S Haider T Kamal and M Ul-Islam ldquo(ermaldecomposition of metal complex precursor as route to thesynthesis of Co3O4 nanoparticles antibacterial activity andmechanismrdquo Journal of Alloys and Compounds vol 704pp 296ndash302 2017
[43] E M M Ibrahim L H Abdel-Rahman A M Abu-DiefA Elshafaie S K Hamdan and A M Ahmed ldquo(e synthesisof CuO andNiO nanoparticles by facile thermal decompositionof metal-Schiff base complexes and an examination of theirelectric thermoelectric and magnetic Propertiesrdquo MaterialsResearch Bulletin vol 107 pp 492ndash497 2018
[44] S Farhadi M Javanmard and G Nadri ldquoCharacterization ofcobalt oxide nanoparticles prepared by the thermal de-compositionrdquo Acta Chimica Slovenica vol 63 pp 335ndash3432016
[45] E M Zayed E H Ismail G G Mohamed M M H Khaliland A B Kamel ldquoSynthesis spectroscopic and structuralcharacterization and antimicrobial studies of metal com-plexes of a new hexadentate Schiff base ligand Spectropho-tometric determination of Fe(III) in water samples using arecovery testrdquo Monatshefte fur Chemie-Chemical Monthlyvol 145 no 5 pp 755ndash765 2014
[46] V Milacic D Chen L Ronconi K R Landis-PiwowarD Fregona and Q P Dou ldquoA novel anticancer gold(III)dithiocarbamate compound inhibits the activity of a purified20S proteasome and 26S proteasome in human breast cancercell cultures and xenograftsrdquo Cancer Research vol 66 no 21pp 10478ndash10486 2006
[47] T Mosmann ldquoRapid colorimetric assay for cellular growthand survival application to proliferation and cytotoxicityassaysrdquo Journal of Immunological Methods vol 65 no 1-2pp 55ndash63 1983
[48] R L Siegel K D Miller and A Jemal ldquoCancer statistics2018rdquo CA A Cancer Journal for Clinicians vol 68 no 1pp 7ndash30 2018
[49] S Chattopadhyay S P Chakraborty D Laha et al ldquoSurface-modified cobalt oxide nanoparticles new opportunities foranti-cancer drug developmentrdquo Cancer Nanotechnol vol 3no 1-6 pp 13ndash23 2012
[50] F Zielinski V Tognetti and L Joubert ldquoCondensed de-scriptors for reactivity a methodological studyrdquo ChemicalPhysics Letters vol 527 pp 67ndash72 2012
[51] H Wang Y He Q Yan et al ldquoCorrelation between thedielectric properties and biological activities of human ex vivohepatic tissuerdquo Physics in Medicine and Biology vol 60 no 6pp 2603ndash2617 2015
[52] F Tao F Fu F You et al ldquo(e correlation between dielectricproperties and microstructure of femoral bone in rats withdifferent bone qualitiesrdquo Annals of Biomedical Engineeringvol 42 no 6 pp 1238ndash1249 2014
[53] L Gun D Ning and Z Liang ldquoEffective permittivity ofbiological tissue comparison of theoretical model and ex-perimentrdquo Mathematical Problems in Engineering vol 2017Article ID 7249672 2017
[54] E I Ating S A Umoren I I Udousoro E E Ebenso andA P Udoh ldquoLeaves extract of Ananas sativumas greencorrosion inhibitor for aluminium in hydrochloric acid so-lutionsrdquo Green Chemistry Letters and Reviews vol 3 no 2pp 61ndash68 2010
[55] E Hamed ldquoStudies of the corrosion inhibition of copper inNa2SO4 solution using polarization and electrochemicalimpedance spectroscopyrdquo Materials Chemistry and Physicsvol 121 no 1-2 pp 70ndash76 2010
[56] H Zarrok H Oudda A Zarrouk et al ldquoWeight loss mea-surement and theoretical study of new pyridazine compoundas corrosion inhibitor for C38 steel in hydrochloric acidsolutionrdquo Der Pharma Chemica vol 3 no 6 pp 576ndash5902011
18 Journal of Chemistry
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Journal ofNanomaterials
Submit your manuscripts atwwwhindawicom
We focus here on the preparation and characterization ofthis class of mixed amino acid complexes of four divalenttransition metal ions of Co Ni Cu and Zn
Modelling using DFT theory and TD-DFT will be in-vestigated in an attempt to validate and characterize structuraland electronic properties of M(II) Glu-Arg complexes inaqueous solution (is will shed light on the nature of M-Linteraction Such knowledge is likely to provide some help inthe rational design of new complexes of biological impor-tance Additionally cytotoxicity will be evaluated In-vestigation of the biological activities include g-negative (Paeruginosa and E coli) pathogenic bacteria and g-positive(Streptococcus p and Bacillis sub) pathogenic bacteria
It is known that amino acids act as an eco-friendly in-hibitor for several metals as copper aluminum steel andnickel L-arginine and its zinc complex are used as nontoxicand low-cost corrosion inhibitors for carbon steel [14ndash16](us we will undertake corrosion inhibition abilities studiesof the complexes prepared towards aluminum because theyare widely exploited in automobile aerospace and house-hold industries
Additionally the metal complexes could be consideredas a precursor for thermal preparation of nanosized metaloxides (us we will investigate calcinating the complexesunder investigations to check the possibility of obtainingmetal nano-oxides in a facile way for possible application asphotocatalysts
2 Experimental
21 Materials and Preparation of the Complexes All chem-icals were purchased from Sigma-Aldrich Glutamic acid(CAS Number 56-86-0) and L-arginine (CAS Number 74-79-3) ligands as well as metal carbonates CoCO3middot3Co(OH)2(CAS Number 12602-23-2) NiCO3middot2Ni(OH)2middot4H2O (CASNumber 12607-70-4) CuCO3middotCu(OH)2middotH2O (CAS Num-ber 12069-69-1) and 2ZnCO3middot3Zn(OH)2 (CAS Number5263-02-5) were used without further purifications
[M(II)(Glu)(Arg)] complexes were synthesized followingthe method used in [16] Refluxing equal-molar amounts ofM(II)carbonate (1mmol powder) and water-soluble glutamicacid (1mmol) L-arginine (1mmol) in sim100ml bidistilledwater at about 80ndash363K for 2ndash3 days gives dense precipitateupon scratching (e obtained dense precipitate was filtratedand washed with absolute ethanol Crystallization of the newternary complexes was achieved in absolute ethanolbidistilled water mixed solvent Unfortunately no singlecrystals could be obtained
22 Instrumentation (e contents of C H and N weredetermined by Vario El Elementar while metal percentageswere determined by atomic absorption spectrometry (Per-kinElmer AAs 3100) FTIR spectra of the ligands and thecomplexes in KBr discs were recorded on a Jasco FTIR-300ESpectrometer (400ndash4000 cmminus1 range) microanalytical labo-ratory in the central laboratory of Ain Shams University
Mass spectra were recorded at 350Cdeg and 70 eV onShimadzu GCMS-QP5050A spectrometer and ESR
spectrum of the Cu complex was recorded at room tem-perature using a Bruker ESR-spectrometer model EMX at9706GHz (X-band) using 22-diphenylpyridylhydrazone(DPPH) as standard (g 20037)
Conductivity measurements of 10minus3M aqueous solu-tions (de-ionized water) at 25degC were carried out usingWTW D-812 Weilheim conductivity meter model LBRfitted with a cell model LTA 100
23 +ermogravimetric Analysis (ermogravimetric analy-sis (TGA) of metal complexes was carried out starting fromroom temperature sim303K to 1273K under nitrogen atmo-sphere at a heating rate 283Kmiddotminminus1 using TA instrumentmodel SDT600 Mass spec ESR and TGA analysis were donein National Research Center lab Cairo (e UV-Vis spectrawere recorded in aqueous solutions (10minus2M) at room tem-perature with typical ranges from 800 to 190 nm on Cary 100which is done in the microanalytical laboratory in the centrallaboratory of Ain Shams University
24 Nanosized Metal Oxide Preparation (e metal com-plexes were calcined at 550degC for 6 h and the metal oxidesobtained were characterized by X-ray diffraction scanningelectron microscopy and transmission electron microscopyXRD analysis showed that the obtained oxides are crystallineand corresponded to the Co3O4 CoO and CuO phasesCrystal size and shape were determined by SEM
25 Magnetic Susceptibilities Magnetic susceptibilities weremeasured at room temperature by the Gouy method using amagnetic susceptibility balance JohnsonMatthey Alfa productsmodel MKI Diamagnetic corrections were calculated fromPASCALrsquos constants Mercury tetrakis-thiocyanatocobaltatewas used as a standard (e analysis was carried out in mi-croanalytical laboratory Cairo University
26 Corrosion Inhibition Materials and Methods A purealuminum foil sheet (Al) of 9892 purity which is press-cutto form specimens with dimensions of 1 cmtimes
1 cmtimes 015 cm was usedOne liter of 1M HCl solution was prepared using
deionized water Al samples were immersed for 7 hours in20ml of 1M HCl used as corrosive solution An electronicweighing balance (Easyway-JA 1003A) micrometer heatingmantle and a water bath were used Various concentrations(10minus2ndash10minus5M) of mixed ligands (glutamic acid + arginine bythe ratio 1 1) and their ternary metal complexes wereprepared and dissolved in 1M HCl and examined as in-hibitors for Al corrosion by weight loss method (e mixedratio (1 1) of these two ligands was the same ratio as thatused in preparation of the four metal complexes Before eachrun the surface of Al was polished with different grades ofemery papers degreased with ethyl alcohol washed thor-oughly with double distilled water dried in air and finallyweighed (en these specimens were immersed in 20mlinhibited and uninhibited 1M HCl solution in open con-tainers for 7 h for aluminum specimens as immersion time
2 Journal of Chemistry
then they were withdrawn from the test solution washedwith deionized water and acetone dried and reweighed(econtainer was placed in a water bath maintained at (303plusmn 1)K (e experiments were operated without (blank) and withthe various concentrations of the mixed ligands and thecomplexes separately (e weight loss was taken as thedifference in weight of the specimen before and after theimmersion time (e experiments were carried out in waterbath with temperature range 293ndash313plusmn 1K
27 Biological Activity (e antimicrobial activity of theprepared ternary metal complexes against two gram-positivebacteria (Streptococcus pneumoniae Bacillis subtilis) twogram-negative bacteria (Pseudomonas aeruginosa Escherichiacoli) and four fungi (Aspergillus fumigates Syncephalastrumracemosum Geotricum candidum Candida albicans) wereinvestigated by a Regional Center for Mycology and Bio-technology (RCMB) Al-Azhar University Cairo
28 Cytotoxicity Cytotoxicity evaluation using viabilityassays was performed by a Regional Center for Mycology ampBiotechnology (RCMB) Al-Azhar University Cairo (einhibitory activity of ternary metal complexes is screenedagainst the cell line hepatocellular carcinoma (HepG-2)
29 Computational Methods Density functional theory(DFT) and its time-dependent extension (TD-DFT) theoryemploying BP86D3DEF2-SVP model and auxiliary basisDEF2JK were carried out using Orca 4012 package [17]Our calculation utilizes the atom-pairwise dispersioncorrection with the BeckendashJohnson damping scheme(D3BJ) [18 19] RI approximation [20] was used Overlap-fitted RIJCOSX approximation was also utilized as a speed-up option leading to enhanced speedups [21 22] withalmost no loss of accuracy [23] First we ran a geometryoptimization and frequency job using BP86D3DEF2-SVP)and auxiliary basis def2J [18 19] All frequency modes arereal indicating that the equilibrium geometry is reachedWe used the same model for EPR simulations of thedoublet state In the case of UV-Vis computations weutilized different models including CAM-B3LYP functionalwithout returning a satisfactory result matching the ex-perimental results (e most successful one that producedresult in excellent agreement with the experiment wasBP86D3DEF2-SVP [18ndash20] and utilizing def2J auxiliarybasis We utilized SMD solvation model [24] Spartan 16parallel package (httpswwwwavefuncom) has beenused to obtain the potential energy surfaces (PESs) at theωB97X-D6-31G(D) level of the DFT
A Broadberry workstation (40 cores) (UK) and a MacPro (12 core) workstation were used
3 Results and Discussion
31 Structure and Spectroscopic Properties Elemental ana-lyses (C H N and metal) and physical and chemicalproperties of the prepared ternary complexes are given in
Table 1 where (1) [ComiddotGlumiddotArgmiddot(H2O)2]middot05H2O (2)[NimiddotGlumiddotArgmiddot(H2O)2]middot05H2O (3) [CumiddotGlumiddotArg]middotH2O and(4) [ZnmiddotGlumiddotArgmiddot(H2O)2]middotH2O
(e thermal decomposition of these complexes in therange (511ndash603K) indicates thermal stability (e effer-vescence test with sodium carbonate confirmed that all theprepared complexes are containing free acidic proton (emagnetic moments molecular weight (Mol wt) and molarconductivity values are given in Table 1 (e pH valuesindicate slightly acidic character (e obtained experimentaland theoretical data confirm the suggested structures shownin Figures 1 and 2
(e paucity of information about mixed amino acids(glutamic acid and arginine) metal complexes motivated usto investigate their molecular structures using DFT theory tocharacterize structural and electronic properties consideringCo(II) and Cu(II) Glu-Arg complexes in aqueous solution asrepresentative of all complexes Optimized geometries aredepicted in Figure 1 Such knowledge is likely to providesome help in the rational design of new complexes for theirbiological importance
In this pH range glutamic acid and L-arginine arepredominantly present in their zwitter ion form and eachhas two coordination sites (one N and one COOminus) which areagreed with their distribution coefficients [24] (e analysisand optimized geometry computations suggested that Nithe important vibrational frequencies of arginine glutamicacid and their ternary metal complexes bands (II) andZn(II) complexes are of distorted octahedral structuresimilar to Co(II) complexes Based on 10Dq values of theseternary complexes the distorted octahedral structure issuggested for nickel cobalt and zinc complexes and squareplanar for copper complex Moderate conductivity mea-sured confirms the existence of intramolecular hydrogenbonds Also magnetic moments of the synthesized com-plexes have been measured in order to confirm theirstructures (e data are presented in Table 1
311 IR Spectra (e important vibrational wavenumbers ofarginine glutamic and their ternary metal complexes bandsare listed in Tables 2 and 3 Arginine showed bands at 1698and 1409 cmminus1 assigned for asymmetric and symmetricstretching vibrations of the carboxylate moiety It also showedmedium broadband at 3086 cmminus1 which attributed to theamino NH2 group (e IR spectra of the complexes did notshow any free carboxylic beaks due to strong intramolecularhydrogen bonding Also IR spectra of the four complexesexhibit crowded region between 3500 and 3000 cmndash1 whereH2O ndashOH and ndashNH stretching modes are expected to ab-sorb (e broadband in the range 3300ndash3400 cmndash1 could beattributed to the intramolecular hydrogen bonding(O HndashO O HndashN OndashH N) An example of the IRspectrum is given in Figure 1S Similarly glutamic acid IRspectra (Figure 3S) showed two bands at 1641 1418 and3062 cmminus1 as reported before [25 26]
Upon complexation the NH stretching wavenumber isshifted to 3141ndash3184 cmminus1 indicating that the amino ni-trogen groups are coordinated to the metal atom [27]
Journal of Chemistry 3
Figure 1 (e optimized structure of Co(II) and Cu(II) complexes (dotted lines represent H bonding) indicating the coordination sites ofthe ligands which result in the most stable orientation Ni and Zn complexes have geometries similar to Co complexes
Figure 2 Optimized geometry around the central transition metal ions showing different bond lengths and angle
Table 2 Experimentally and theoretically simulated IR spectra (in cmminus1) of the studied complexes Assignment of experimentally measuredIR key modes
(e C-NH2 stretching bands of the guanidyl group ofalpha amino group have shifted from 1242 to 1175 cmminus1 ofglutamic acid and L-arginine with respect into (1122ndash1131)cmminus1 of the prepared metal complexes In opposite situationarginine has been shown to have two bands observed at 1586and 1608 cmminus1 due to the asymmetrical vibrations of theC-NH2 bonds of the guanidino group which is protonatedto give the guanidinium form without a significant change incase of complexation [28]
(e asymmetrical (υCOOasy) and symmetrical(υCOOsy) carboxylic groups are shifted in the preparedcomplexes to higher or lower values than their values inligands case as shown in Tables 2 and 3 and also thedifference between these bands are more than 200 cmminus1 inall the prepared metal complexes which indicated that thedeprotonated carboxylic groups in both ligands act asmono dentate groups
All the prepared complexes exhibited bands in the rangeof 3340ndash3472 cmminus1 of υ(OH) signifying that H2O moleculesexist in these complexes [29 30]
(e new confirmed bands only appear in the fourprepared complexes at 538ndash572 cmminus1 and 412ndash456 cmminus1which are assigned to υ(M-O) and υ(M-N) stretching bandsrespectively [31]
(e optimized geometry of the complexes shows dis-torted overall octahedral (or better the square pyramidalC4v-local symmetry of Co(II) ion) for the Co(II) complexand the slightly distorted square planar coordination of theCu(II) ion in the Cu(II) complex Ni and Zn complexes areof similar geometry to the Co complexes Figure 3 shows thatthe local symmetry of both centrosymmetric cations isnoticeably distorted with different M(II)-O and M(II)-Nbond lengths and bond angles indicated in Figure 2
(e simulated PES maps [32] which shed light on thebinding sites of the complexes are depicted in Figure 3Inspection of Figure 3 shows that Co(II) complex exhibits
larger positive potentials (299 kJmol) than Cu(II) complexwhich bears enhanced negative potential than that on Co(II)complex (the difference between negative and positive po-tential energy limits (Delta) PES 24 and minus9 kJmol forCo(II) and Cu(II) complexes respectively) (us Cu(II)complex could act as nucleophile whereas Co(II) complex isof enhanced electrophilic nature during interactions
312 Mass Spectra (e mass spectra of the four complexeswere recorded and provided good evidence and confirma-tion of the molecular weight of these complexes (molecularion peaks (MIPs) are detected under severe experimentalconditions [16] which results in of splitting of crystallinewater) (Figure 2S shows the mass spectrum of Zn(II)complex as example)
313 UV-Vis Absorption Spectra Figure 4 shows the the-oretical and experimental UV-Vis spectra of Co(II) andCu(II) as examples (e results confirm that 1 2 and 4complexes have almost tetragonal distorted octahedralstructure (C4v-local symmetry) with different distortiondegrees which is obvious from the wavenumber and 10Dqvalues of the complexes compared to their literature values[33] Cu complex exhibits slightly distorted square planarshape Table 4 shows electronic spectral data and ligand fieldparameters such asDq B (free ion) B (complex) and β usingband-fitting equation [34 35]
(e value of Racah parameter B (free ion) is larger thanthat of B (complex) due to the covalence bonding of thecomplex (e value of β (nephelauxetic ratio)lt 1 is calcu-lated according to equation (1) βlt 1 validating octahedralgeometry [34 35]
β B(free ion)
B(complex) (1)
Table 3 Experimentally and theoretically simulated IR spectra (in cmminus1) of the studied complexes Assignment of theoretically calculated IRkey modes for Co(II) and Cu(II) complexes in the gas phase Excellent match between experimentally determined and theoreticallycomputed IR modes in case of Ni and Zn complexes is obtained
Complex υ (OH) υ (COO) υ (M-O) υ (M-N)
[Co(glu)(arg)(H2O)2]middotH2O2513 (H-bonded H2O and O of COO of Gu) 16848 (Ar) 5543 46363521 1740 (Gu)
Spectral data and assignments are summarized inTable 4
10Dq for the nickel complex was determined by twoprocedures [34]
(e first one is by solving equations (2) and (3) using theenergy terms of the different triplet states transitions sup-plied for Ni(II) [34] as shown in Table 4
(en applying the trial and error procedure a value for∆ that fits in equations (2) and (3) was found to be10935 cmminus1 which suggested the octahedral structure (esecond method for calculating 10Dq used Tanabe andSugano diagrams for the different metal ion complexesFrom Ni(II) diagram we could be able to deduce the ex-pected positions of the (3A2g⟶ 3T2g) and the(3A2g⟶ 3T1g) transitions (is method corresponds to a
pure crystal field approach and assumes that the value ofthe free ion Racah parameter (B) is maintained in thecomplex
Applying this procedure and considering the ratio of ]1]2 1582225641 062 the best vertical line which fulfilsthis ratio cuts the ∆B axis at a value of 139 and Bcomplexis calculated by equation (4) We found the value765273 cmminus1
299
ndash275
299
ndash275
(a)
272
ndash272
272
ndash272
(b)
Figure 3 PES maps (a) Co complex (upper pan solid surfaces and lower pan clipped surfaces) and legend color codes given in kJmol(b) Cu complex (upper pan solid surfaces and lower pan clipped surfaces)
(4) mdash mdash 221 ]1 45249 Charge transfer mdash mdash
Tetragonal distortionpseudosquarepyramidal
(distorted octahedral)
Journal of Chemistry 7
Bcomplex 2v21 + v22 minus 3v1v2( 1113857
15v2 minus 27v1( 1113857 (4)
(en 10Dq 10637253 cmminus1 is compared to the value of10935 cmminus1 obtained by the first method and both valuesconfirm octahedral structure [34] (e magnetic moment ofthe nickel complex was 31 which also confirmed octahedralstructure [16]
Racah parameters for Co(II) complex is also calculatedsimilarly
Furthermore Co(II) complexes have the effectivemagnetic moment μeff 413 (is value is higher than spinonly moment for three unpaired electrons 389 due to aconsiderable orbital contribution [34 36]
(e Zn complex did not show any d-d transitions butdisplayed charge transfer bands as shown in Table 4 (eexistence of charge transfer was due to transition betweentwo different principle quantum numbers from three to fouras distorted tetrahedron being completed by two watermolecules and forms zinc octahedral complex [34ndash37]
(e longest wavelength weak peaks are observed at516 nm (ε middotM 206 Lmiddotmolminus1middotcmminus1) and 636 nm (ε middotM
179 Lmiddotmolminus1middot cmminus1) for Co(II) and Cu(II) complexes re-spectively (e use of TD-DFT at BP86 DEF2-SVP andauxiliary basis DEF2JK level in water (using SMD solvationmodel) [24] results in λmax Co 5291 nm (oscillatorstrength f 0003) and λmax Cu 6486 nm (f 00256)which are in excellent agreement with the experimentalresults
(e computed natural transition orbitals of the longestwavelength transitions in both complexes reveal the largest(greater than 82) contribution of beta HOMO-LUMOwith minor (about 108) contribution of alpha HOMO-LUMO in case of Co(II) complex and about 992 con-tribution from the beta-HOMO-LUMO in case of Cu(II)complex MOs involved in the electronic transitions aredepicted in Figure 5 which illustrate clear dxz or dyz(e)⟶ dz2 (a1) transition in the local square pyramidal(C4v) of Co(II) ion in the Co(II) complex Metaldxy(b2g)minus dx2 minusy2(b1g) transition is dominant in case oflocal square planar symmetry of the Cu(II) complex (is isapproved by low molar absorptivity experimentally ob-served in the UV-Vis spectra of both complexes andsupported by low value of the computed oscillatorstrengths of the forbidden d-d transitions which acquiresome allowness due to geometry distortion of bothcomplexes
314 ESR Spectra For elucidation of the geometry of thecopper ternary complex ESR measurement gives veryuseful information about the stereo chemistry bondingbetween copper and ligands Figure 1S shows the ESRspectrum of the copper complex with a comparativeadvantage and axial symmetry (g || (parallel) 210748g (perpendicular) 201232 (204984) (ese valuesconfirm square planar coordination in which g || gt g gt 2so the unpaired electron found in the dx2 minus y2 orbital andthe ground state is 2B1g [38] (e observed and calculated
g values are different from ge 20023 due to spin-orbitcoupling (e computed g components are not equalreflecting anisotropic effect and the value of g changes as afunction of the orientation of the molecule relative to theexternal magnetic field (is value is close to the spin onlyvalue and it is in a fair agreement with the computed electronspin only value of ge(computed) 20498 [38] Co(II) com-plex is characterized by g 21280 (e simulated EPRspectrum of Co(II) complex returns ge value of 21085
Different values of Mulliken spin density are shown inFigure 4S in such metal-chelates point to purely anisotropiccouplings (e unpaired electron is totally localized onCo(II) ion In case of Cu(II)-complex electron spin pop-ulation is more distributed with about 46 on the Cu(II)ion(is may result in the simulated significant HF couplingin the case of chelating atoms around Cu(II) ion (e datapoint to mixed copper-nitrogen and copper-oxygen bondsin agreement with the computed optimized geometry [38]
32 +ermal Analysis (ermogravimetric analysis (TGA)for the all prepared ternary metal complexes was carried outin nitrogen atmosphere (e thermal decomposition of thefour complexes displayed similar patterns as their ligands
It is well known that amino acids exist only in solid stateso their thermal decomposition has been endothermal be-tween minus72 and minus151 kJmol when heating in range between185degC and 280degC (eir thermal decomposition releasesthree gases mainly H2O less NH3 and hardly any CO2TGA gives the weight of these gases as weight loss calcu-lations which evolve in appreciable amount [39]
Also the thermal decomposition of L-arginine-dopedKDP potassium dihydrogen phosphate crystal started to loseweight with temperature from 341K to 393K releasedammonia and water molecules gases [40]
(e amino acids are totally broken within the range603ndash793K as shown in Figure 6 and Table 5 (e first stepsare weight loss of the three gases H2O NH3 and CO2 withintemperature range about sim423ndash623K (e hydrocarbonsmatter loses weight in the temperature range sim350ndash520degC(e residues for these complexes are mixture with differentratios of metal and metal oxide above temperature range643ndash793K
It is noteworthy to mention that the geometries of thestudied complexes are similar to L-arginine metal complexreported before [41] which have been confirmed by X-raycrystallographic data of single crystals
33 Nanosized Metal Oxides Characterization
331 XRD of Nano CuO and Nano Cobaltosic Oxide(Co3O4) XRD of thermal synthesized copper oxide nano-particles starting from copper glutamic arginine-mixed li-gands complex gives characteristic peaks at 2θ 326deg 356deg387deg 489deg 536deg 582deg 616deg 663deg and 681deg for the markedindices of (110) (002) (111) (202) (020) (202) (113) (022)and (113) respectively as shown in Figure 7(a) which iscomparable with the literature values (e average primaryparticle size of the copper(II) oxide nanoparticles was
8 Journal of Chemistry
TG (m
g)
80
60
40
20
DTG
(mgmiddot
min
ndash1)
000
ndash020
ndash040
ndash060
ndash080
Weight loss ndash1925mgndash24174
Weight loss ndash1745mgndash21914
Weight loss ndash1366mgndash17154
Weight loss ndash0710mgndash8916
Weight loss ndash0276mgndash3466
273 473 673 873 1073 1273Temperature (K)
(a)
273 473 673 873 1073 1273Temperature (K)
TG (m
g)
100
50
DTG
(mgmiddot
min
ndash1)
000
ndash020
ndash040
ndash060
Weight loss ndash1890mgndash14111 Weight loss ndash8641mg
ndash64514
(b)
Figure 6 Continued
Alpha HOMO Alpha LUMO
Beta HOMO Beta LUMO
(a)
Alpha HOMO Alpha LUMO
Beta HOMO Beta LUMO
(b)
Figure 5 Frontier MOs of (a) Co(II) complex and (b) Cu(II) complex involved in the longest wavelength electronic transition Surfacessimilar to that of Co complex are obtained in case of Ni (ere are no d-d transitions in Zn complexes
Journal of Chemistry 9
Table 5 (ermogravimetric analysis decomposition data for the metal ternary complexes
Complexes Mol (wt) TG range (degC) Mass loss () found (calculated) Total mass loss () Assignment
Figure 6 TG and DTG of (a) [Co(glu)(arg)(H2O)2]middot05H2O (b) [Ni(glu)(arg)(H2O)2]middot05H2O (c) [Cu(glu)((arg)]middotH2O and(d) [ZnmiddotGlumiddotArgmiddot(H2O)2]middotH2O
10 Journal of Chemistry
estimated using well-known DebyendashScherrer formula usingthe full width at half maximum (FWHM) of the (111) peaksin the XRD K(α) is the wavelength of X-ray source(15406 A 015406 nm) β∆θ is the full width at halfmaximum (FWHM 01378) and θ 387 is the diffractionangle corresponding to the lattice plane (111) which gives Dsim143ndash204plusmn 08 nm patterns [42ndash44]
(e pattern of XRD for cobalt oxide nanoparticles showscharacteristic peaks at 2θ values at 1898deg 3127deg 3682deg3848deg 4478deg 5568deg 5934deg 6521deg and 7731deg which arecorresponding to their indices (111) (220) (311) (400) (511)and (440) in agreement with JCPDS Card No 76ndash1802 (ispattern confirms the phase formation of cobalt oxidenanoparticle Figure 7(b) (e average size of the Co3O4particles was calculated by the DebyendashScherrer equationDK(α) λ(β cos θ) whereD is the average crystalline size λ isthe wavelength of CuKα θ is Braggrsquos angle and β is the fullwidth at half maximum (FWHM) of the diffraction peak (eaverage dimension D is sim147ndash182plusmn 06 nm at 2θ 3682degwhich is the intense peak [44]
332 EDX of Nano CuO (e synthesized nano copperoxide is confirmed by the EDX spectrum and SEM imagemeasurement shown in Figure 8 which confirms the highestformation percent of CuO and traces of copper carbide (eSEM image for nano copper oxide CuO shows a mixingnanosize 270sim1079 nm [42 43]
333 EDX of Nano Cobaltosic Oxide (e synthesized nanocobalt oxide is confirmed by the EDX spectrum measure-ment shown in Figure 9 which confirms the highest for-mation percent of cobaltosic oxide Co3O4 and traces ofcobalt carbide (e SEM image for nano cobaltosic oxideCo3O4 shows a mixing nanosize 318ndash8543 nm
34 Applications
341 Biological Activity Mixed ligand ternary complexeshave been examined for their in vitro antimicrobial activity(is investigation was performed using the diffusion agartechnique (Figure 5S) (e assays collection included
g-negative (Pseudomonas aeruginosa RCMB 010043 andEscherichia coli RCMB 010052) pathogenic bacteria usingGentamicin 5mgml as a reference compound and g-pos-itive (Streptococcus pneumoniae RCMB 010010 and Bacillissubtilis RCMB 010067) pathogenic bacteria using Ampi-cillin 5mgml as a reference compound It was also in-cluded four fungi (Aspergillus fumigatus RCMB 02568Syncephalastrum racemosum RCMB 05922 Geotrichumcandidum RCMB 05097 and Candida albicans RCMB05036) using Amphotericin B 5mgml as a referencecompound [30 45]
(e inhibitory effects of the used ligands and theirternary polymer complexes against the used organisms aregiven in Table 6 In general the used ligands did not displayantifungal or antibacterial inhibitory
For antifungal assay examination and based on theminimum inhibitory concentration (MIC) values it is foundthat the inhibitory effect of all the ternary complexes varyfrom moderate to weak against Amphotericin B controlexcept in the case of Candida albicans (RCMB 05036) whichis not affected by both cobalt and zinc complexes
(e antibacterial activities of the obtained ternarycomplexes are determined in terms of MIC values As shownin Table 6 all complexes display moderate activities againstStreptococcus pneumonia (RCMB 010010) and Bacillis sub-tilis RCMB 010067 (e growth of the gram-negative bac-teria Pseudomonas aeruginosa RCMB 010043 andEscherichia coli RCMB 010052 is extremely affected by bothcopper and nickel complexes which display strong inhibitionagainst the gram-negative pathogenic bacteria with MICvalue less than the Gentamicin control (e remainingcomplexes do not display the same behavior during theassay
342 Cytotoxicity One of the fundamental goals in me-dicinal chemistry is the development of new anticancer andantimicrobial therapeutic agents Cancer treatment usingmetal-based drugs is one of the very effective strategies as themetal ions are capable of binding to nucleic acids stereo-specifically with varying strength
In vitro anticancer activity evaluation of the newlysynthesized compounds was carried out against human
Cou
nts
400
300
200
100
010 20 30 40
Angles (deg2θ)50 60 70
(a)
Cou
nts
100
50
010 20 30 40
Angles (deg2θ)50 60 70
(b)
Figure 7 XRD pattern of (a) copper oxide CuO and (b) cobalt oxide Co3O4 prepared by thermal decomposition at 550Cdeg starting frommetal glutamic arginine mixed ligands complex
Journal of Chemistry 11
cancer cell lines hepatocellular carcinoma (HePG2) becauseliver cancer is the third most common cause of death incancer using MTT method [26 46 47]
Doxorubicin HCl is one of the most effective anti-cancer agents is used as a reference drug in this study (eobtained results from Table 2S indicated that most of thesemoleculesrsquo behavior can be observed from the values of the
half maximal inhibitory concentration IC50 whichfor glutamic and arginine are 167 and 376 μgmlrespectively
IC50 results indicate that the ternary complexes havepromised inhibition of HePG2 liver tumors [48 49]
Cell viability was assessed by themitochondrial-dependentreduction of yellow MTT (3-(45-dimethylthiazol-2-yl)-25-
108K096K084K072K060K048K036K024K012K000K
000 100 200 300 400 500 600 700 800 900
Cu Kβ
Cu Kα
Cu L
O KC K
(a) (b)
Figure 8 EDX and SEM images of CuO obtained by thermal decomposition at 550Cdeg starting from copper glutamic arginine mixed ligandscomplex
135K120K105K090K075K060K045K030K015K000K
000 100 200 300 400 500 600 700 800 900
O K
Co L Co Kα
Co Kβ
(a) (b)
Figure 9 EDX and SEM images of Co3O4 obtained by thermal decomposition at 550Cdeg starting from cobalt glutamic arginine mixedligands complex
Table 6 Antimicrobial activity of prepared ternary metal complexes
Sample tested microorganisms Glutamicacid L-arginine (1) (2) (3) (4) Standard
lowastNA no activity Values in bracket are the MIC values
12 Journal of Chemistry
diphenyl tetrazolium bromide) to insoluble purple formazan[45] (e prepared ternary metal complexes are of differentviability percentages as depicted in Figure 10 Data of bothligands are also included for comparison
Table 2S shows that the ligands have lower inhibition ofHePG2 than their metal ternary complexes (e coppercomplex introduces the highest inhibition
Additionally Table 7 summarizes some computedelectrical reactivity [50] and thermodynamic propertiesfor Co(II) and Cu(II) complexes (as maximum andminimum IC50 of the four prepared ternary metalscomplexes) which are correlated with the inhibition ofhuman cancer cells and are useful to explain the roleplayed by molecular properties in inhibition of humancancer cells
(e simulated data summarized in Table 7 conclude thefollowing
(i) Cu complex is more energetically stable relative toCo complex by about minus265 kJmol
(ii) Cu complex is characterized by lower dipole mo-ment and lower polarizability relative to Co(II)complexes
(iii) Enthalpy and Gibbs free energy of the Cu complexesare more stable by about minus265 kJmol relative toCo(II) complex Lower entropy reflects lower degreeof randomness of Cu(II) complex
(iv) (e chemical potential (μprime) (negative of molecularelectronegativity) of Cu(II) complex is much higherthan that of Co(II) complex reflecting the enhancedreactivity of Cu(II) complex as nucleophile becauseμprime measures the escaping tendency of electrons fromthe complex (μprime (LUMO+HOMO)2) [50]
(v) Cu complex is characterized by lower hardness thanCo(II) complex Hardness measures the resistanceto electron transfer (η (LUMO-HOMO)2) [50]
It seems that more thermodynamically stable and lesspolar Cu complex exhibits that enhanced responsive elec-tron cloud transfer to the surrounding tumor relative to theCo(II) complex (ese quantitative molecular descriptors[50] explain the promising inhibition activity of the Cu(II)complex (e results are correlated with the above-discussedPES results which show that Cu complex could act asnucleophile whereas Co complex is of enhanced electro-philic nature
(e nucleophilicity of Cu complex (seeking for positivelycharged sites of the reactant) together with its electricalthermodynamic and molecular properties favors its prom-ising inhibition activity towards HePG2 cancer cell [51ndash53]
343 Corrosion Inhibition of Aluminum An assessment ofcorrosion rates and inhibition efficiency for aluminum withdifferent inhibitor concentrations were computed as followscorrosion rate Rcorr was computed using equation (5)
Rcorr M1 minusM2( 1113857(mg)
A cm2( ) times t(h) (5)
where M1 weight (g) before immersion M2 weight (g)after immersion A area (cm2) of the specimen andt exposure time (h)
(e inhibition efficiency (IE) was evaluated usingequation (6)
IE Rblank minusRinh
Rblank1113890 1113891 times 100 (6)
120
60
100
80
60
40
20
00 10 20 30 40 50
GlutamicLarginineCu(II)
Ni(II)Co(II)Zn(II)
Figure 10 Cell viability of (HePG2) at different concentrations of ligands and the prepared metal complexes
Table 7 Simulated electrical properties of complexes studied exhibiting enhanced inhibition of HePG2
where Rblank corrosion rates in the absence of inhibitor andRinh corrosion rates in the presence of inhibitor [16]
Table 8 shows the calculated corrosion rates and inhibitionefficiencies of aluminum specimens in aqueous solution of 1MHCl as the corrosive medium in absence and presence ofmixed ligands and their ternary metal complexes at differenttemperatures (293 ndash313) K for 7 hours of each concentrationFigure 6S shows that as the concentration of ligands and theircomplexes increases Rcorr decreases and IE increases formixed ligands and their metal complexes acted as more ef-ficient inhibitors than their mixed ligands alone
344 Adsorption Isotherms and the +ermodynamic Acti-vation Parameters (e metal surface coverage degree(θIE100) was subjected to different adsorption iso-therms (e well fit for weight loss data is obtained forLangmuir adsorption isotherm Figure 11
Table 8 Corrosion parameters for aluminum in aqueous solution of 1M HCl in the absence and presence of different concentrations ofmixed ligands and their metal complexes at different temperatures for 7 hrs
Inhibitors C (times10minus2M)Corrosion rate times10minus4
Figure 11 Langmuir adsorption isotherms of the mixed ligands(L) and their metal complexes
14 Journal of Chemistry
(e temperature effect (293ndash313 K) on aluminum weightloss inhibition may be attributed to two main mechanismsphysical and chemical adsorption [37] (e suggested mech-anisms are obtained as the temperature increases the efficiencydecreases for mixed ligands but increases for their metalcomplexes depending on the nature of bond formation be-tween the mixed ligands and aluminum surface which isdifferent from the nature of bond formation between metalcomplexes and the aluminum surface [16] Arrhenius equation(7) gives the relation between the corrosion rate andtemperature
lnRcorr lnAminusElowast
RT (7)
where A is the Arrhenius factor Elowast is the apparent activationenergy of the corrosion process R is the rate gas constant andT is the absolute temperature (e straight line slope oflogRcorr vs 1T for aluminum 1M HCl at 4times10minus4molL after7 h is minusElowast2303R for the inhibitors (Figure 12)
(e activation thermodynamic parameters for alumi-num dissolution could be obtained from the transition stateequation (8)
lnRcorr
T1113874 1113875 ln
R
Nh1113874 1113875 +
ΔSlowast
R1113888 1113889minus
ΔHlowast
RT1113888 1113889 (8)
where the entropy of activation ∆Slowast and the apparent en-thalpy of activation ∆Hlowast can be obtained from the intercept
3150
02
04
06
logR
corr
(gmiddoth
ndash1middotcm
ndash1)
08
1
12
32 325 331000T(Kndash1)
335 34 345
BlankMix ligandsZn2+
Co2+Ni2+Cu2+
Figure 12 Arrhenius of log corrosion rate (Rcorr) vs 1T for aluminum in 1M HCl without and with 004times10minus2MLminus1 of inhibitors (mixedligands and their metal complexes)
Table 9 (ermodynamic parameters for the adsorption of (004times10minus2)ML mixed ligands and their metal complexes on aluminum metalin aqueous solution of 1M HCl at different temperatures for 7 hrs
and the slope for the straight line of the relation betweenln(RcorrT) vs (1T) respectively N is Avogadrorsquos numberand h is Planckrsquos constant (e Gibbs free energy of acti-vation ∆Glowast can be detected by equation (9)
ΔGlowast ΔHlowast minusTΔSlowast (9)
Table 9 shows the thermodynamic parameters for theadsorption of mixed ligands and their metal complexes (epositive value of ∆Hlowast indicated the endothermic property ofdissolution process nature for aluminum in the acidicmedium [54]
However the blank ΔHlowast value is higher than the in-hibitor metal complexes which indicated that the inhibitionefficiency generally increases with increasing temperature(e association step is the rate-determining step rather thana dissociation process in presence of the metal complexesinhibitors due to the negative values of ΔSlowast It is known thatthe values of ΔGlowast above 40 kJmiddotmolminus1 are referred to chargetransfer from the inhibitor molecules into aluminum surfaceto form coordinated compound on the Al surface whichblocks it against corrosion process by different degrees Alsothe chemical adsorption process mechanism is confirmed bythe values of ΔGlowast above 40 kJmiddotmolminus1 [16 54ndash56]
4 Conclusions
Novel coordination materials of ternary divalent metalions (Cu(II) Ni(II) Co(II) and Zn(II)) chelated by thebidentate glutamic acid (Glu) and L-arginine (Arg) aminoacids are synthesized and characterized (e metal ionscomplexes are modelled using density DFT and TD-DFTtheory Computed molecular and spectroscopic (IR UV-Vis and EPR) properties validated the experimental re-sults (e used computational methods are capable ofproviding good structural descriptions for the TM com-plexes Consistent with the experimental properties theoptimized structures of the complexes [Cu(II) Glu-Arg]and [Co(II) Glu-Arg (H2O)2] reveal that symmetry en-vironment of Cu(II) exhibits slightly distorted squareplanar shape whereas Co(II)-complex has a distortedoctahedral (where Co(II) central ion is of C4v-localsymmetry) Spectral properties of [Ni(II) Glu-Arg(H2O)2] and [ZnmiddotGlumiddotArgmiddot(H2O)2] complexes indicatethat they have similar structure as Co(II) complex All thestudied ternary metal complexes are of different anti-fungal activities ranging from moderate to weak withoutpractically noticed inhibitory effects whereas antibacte-rial activities of all studied metal complexes show sig-nificant effects
Cytotoxicity studies against (HePG2) reveal the prom-ising potentiality of Cu(II) complex as inhibitor of cancercells(e results are correlated with the computed moleculardescriptors including dipole moment polarizability ther-modynamics and reactivity properties as well as the PESmaps
(e corrosion inhibition of aluminum metal specimensin 1M HCl is efficiently achieved by mixed ligands and theirmetal complexes studied
Data Availability
(e data used to support the findings of this study areavailable from the corresponding author upon request
Conflicts of Interest
(e authors declare that they have no conflicts of interest
Supplementary Materials
(e supplementary materials consist of six figures and twotables to further clarify the structures and trends of the newlyprepared metal ternary complexes (SupplementaryMaterials)
References
[1] Z Ozturk D A Kose A Asan et al ldquoPorous metal-organicCu(II) complex of L-Arginine 2synthesis characterizationhydrogen storage properties and molecular simulation cal-culationsrdquo Hittite Journal of Science and Engineering vol 1no 1 pp 1ndash5 2014
[2] S A Lahsasni R A Ammar M F Amin et al ldquoMixed-ligandcomplex formation of Cu(II) with 12- diphenylethylenedi-amine as primary ligand and amino acids as secondary li-gandsrdquo International Journal of Electrochemical Sciencevol 7 pp 7699ndash7711 2012
[3] H Sigel B P Operschall S S Massoud B Song andR Griesser ldquoEvidence for intramolecular aromatic-ringstacking in the physiological pH range of the mono-deprotonated xanthine residue in mixed-ligand complexescontaining xanthosinate 5prime-monophosphate (XMP)rdquo DaltonTransactions vol 46 no 46 pp 5521ndash5529 2006
[4] S Udhayakumar K G Shankar S Sowndarya S VenkateshC Muralidharan and C Rose ldquol-Arginine intercedes bio-crosslinking of a collagen-chitosan 3D-hybrid scaffold fortissue engineering and regeneration in silico in vitro and invivo studiesrdquo RSC Advances vol 7 no 40 pp 25070ndash250882017
[5] P K Datta M Chandra and A K Dey ldquoTernary complexesof copper(II) nickel(II) and zinc(II) with nitrilotriacetic acidas a primary ligand and some phenolic acids as secondaryligandsrdquo Transition Metal Chemistry vol 5 no 1ndash3 1980
[6] J S Woertink L Tian D Maiti et al ldquoSpectroscopic andcomputational studies of an end-on bound superoxo-Cu(II)complex geometric and electronic factors that determine theground staterdquo Inorganic Chemistry vol 49 no 20pp 9450ndash9459 2010
[7] S Dutta S Ray K Nagarajan et al ldquoGlutamic acid analoguesused as potent anticancer a reviewrdquo Der Pharma Chemicavol 3 no 2 pp 263ndash272 2011
[8] T Sismanoglu S Pura and A Bastug ldquoBinary and ternarymetal complexes of Congo red with amino acidsrdquo Dyes andPigments vol 70 no 2 pp 136ndash142 2006
[9] R N Patel H C Pandey K B Pandeya et al ldquoMixed ligandcomplex formation of nickel(II)copper(II) and zinc(II) withsome amino acids and imidazolesrdquo Indian Journal ofChemistry-Section A Inorganic Physical +eoretical andAnalytical Chemistry vol 38 no 8 pp 850ndash853 1999
[10] L Meng and Z Lin ldquoComplexations of alkalialkaline earthmetal cations with gaseous glutamic acidrdquo Computational and+eoretical Chemistry vol 1039 pp 1ndash10 2014
16 Journal of Chemistry
[11] L D Pinto P A L Puppin V M Behring O C AlvesN A Rey and J Felcman ldquoSolution and solid state study ofcopper(II) ternary complexes containing amino acids of in-terest for brain biochemistry-2 homocysteine with aspartateglutamate or methioninerdquo Inorganica Chimica Acta vol 386pp 60ndash67 2012
[12] A Wojciechowska A Ggor and W Zierkiewicz ldquoChiraloctahedral complexes of Co(III) as catalysts for asymmetricepoxidation of chalcones under phase transfer conditionsrdquoRSC Advances vol 5 no 46 pp 36295ndash36306 2015
[13] B M Weckhuysen A A Verberckmoes L Fu andR A Schoonheydt ldquoZeolite-encapsulated copper(II) aminoacid complexes synthesis spectroscopy and catalysisrdquo Journalof Physical Chemistry vol 100 no 22 pp 9456ndash9461 1996
[14] K Y El-Baradie N A El-Wakiel and H A El-GhamryldquoSynthesis characterization and corrosion inhibition in acidmedium ofl-histidine Schiff base complexesrdquo Applied Or-ganometallic Chemistry vol 29 no 3 pp 117ndash125 2015
[15] S S R Anthony and R Susai ldquoInhibition of corrosion ofcarbon steel in well water by arginine-Zn2+ systemrdquo Journal ofElectrochemical Science and Engineering vol 2 no 2pp 91ndash104 2012
[16] E H Isamil F F AlBlewi N Soliman and M M H Khalilldquo(ermal studies and mass loss inhibition for some newmixed amino acid metal complexes with their applicationsrdquoJournal of +ermal Analysis and Calorimetry vol 125 no 1pp 289ndash300 2016
[17] F Neese ldquo(e ORCA program system 4012rdquo Wiley In-terdisciplinary Reviews Computational Molecular Sciencevol 2 no 1 pp 73ndash78 2012
[18] S Grimme S Ehrlich and L Goerigk ldquoEffect of the dampingfunction in dispersion corrected density functional theoryrdquoJournal of Computational Chemistry vol 32 no 7pp 1456ndash1465 2011
[19] S Grimme J Antony S Ehrlich and H Krieg ldquoA consistentand accurate ab initio parametrization of density functionaldispersion correction (DFT-D) for the 94 elements H-Purdquo+e Journal of Chemical Physics vol 132 no 15 article154104 2010
[20] F Weigend ldquoHartree-Fock exchange fitting basis sets for H toRnrdquo Journal of Computational Chemistry vol 29 no 2pp 167ndash175 2008
[21] F Neese F Wennmohs and A Hansen ldquoEfficient ap-proximate and parallel Hartree-Fock and hybrid DFT cal-culations A lsquochain-of-spheresrsquo algorithm for the Hartree-Fock exchangerdquo Chemical Physics vol 356 no 1ndash3pp 98ndash109 2009
[22] R Izsak and F Neese ldquoAn overlap fitted chain of spheresexchange methodrdquo Journal of Chemical Physics vol 135no 14 article 144105 2011
[23] T Petrenko S Kossmann and F Neese ldquoEfficient time-dependent density functional theory approximations forhybrid density functionals analytical gradients and paralle-lizationrdquo Journal of Chemical Physics vol 134 no 5 article054116 2011
[24] A V Marenich C J Cramer and D G Truhlar ldquoUniversalsolvation model based on solute electron density and on acontinuum model of the solvent defined by the bulk dielectricconstant and atomic surface tensionsrdquo Journal of PhysicalChemistry B vol 113 no 18 pp 6378ndash96 2009
[25] S Donovan C Stiefbold and K Sprague ldquoChapter 3Chemical properties of amino acids and identification ofunknown amino acidsrdquo in Proceedings of the 17 thWorkshopConference of the Association for Biology
Laboratory Education (ABLE) vol 17 pp 35ndash70 Bain-bridge GA USA March 1996
[26] C C Wagner J Enrique and C Claudia ldquoVibrational andmagnetic properties of a CuMg glutamate complexrdquoArgentina Acta Farm Bonaerense vol 22 no 2 pp 137ndash1422003
[27] M Arif R Sur and M Arshad ldquoStudies on the thermaldecomposition of copper (II) flouride complexes with variousamino acids in nitrogen atmosphererdquo Turkish Journal ofChemistry vol 25 pp 73ndash79 2001
[28] A Ghosh M J Tucker and R M Hochstrasser ldquoIdentifi-cation of arginine residues in peptides by 2d-IR echo spec-troscopyrdquo Journal of Physical Chemistry A vol 115 no 34pp 9731ndash9738 2011
[29] K Nakamoto Infrared Spectra of Inorganic and CoordinationCompounds Part B Wiley-Interscience New York NY USA5th edition 1997
[30] E Santi M H Torre E Kremer S B Etcheverry andE J Baran ldquoVibrational spectra of the copper(II) and nick-el(II) complexes of piroxicamrdquo Vibrational Spectroscopyvol 5 no 3 pp 285ndash293 1993
[31] H N Aliyu and A S Mohammed ldquoSynthesis spectropho-tometric and biological activity of nickel (II) and copper (II)complexes with schiff base derived from acetylacetone andhistidinerdquo Global Advanced Research Journal of Microbiologyvol 1 no 5 pp 67ndash71 2012
[32] J S Murray and P Politzer ldquo(e electrostatic potential anoverviewrdquo Wiley Interdisciplinary Reviews ComputationalMolecular Science vol 1 no 2 pp 153ndash163 2011
[33] E R Souaya M M H Khalil and E H Ismail ldquoSynthesis andcharacterization of ternary complexes of certain hydroxylacids and their biological applicationsrdquo Research Journal ofPharmaceutical Biological and Chemical Sciences vol 5 no 4pp 18ndash30 2014
[34] N N Greenwood and A Earnshaw A Review of Chemistry ofthe Elements Pergamon Press Oxford UK 1984
[35] V Reddy N Patil and S D Angadi ldquoSynthesis character-ization and antimicrobial activity of Cu(II) Co(II) and Ni(II)complexes with ON and S Donor ligandsrdquo E-Journal ofChemistry vol 5 no 3 pp 577ndash583 2008
[36] F A Cotton G Wilkinson C A Murillo et al Advances inSchiff Base Chemistry Wiley New York NY USA 6th edi-tion 1999
[37] M M H Khalil E H Ismail S A Azim and E R SouayaldquoSynthesis characterization and thermal analysis of ternarycomplexes of nitrilotriacetic acid and alanine or phenylala-nine with some transition metalsrdquo Journal of +ermalAnalysis and Calorimetry vol 101 no 1 pp 129ndash135 2010
[38] F Mabbs and D Colisson Electron Paramagnetic Resonanceof D Transition Metal Compounds Vol 102 ElsevierAmsterdam Netherlands 1992
[39] M M H Khalil E R Souaya E H Ismail et al ldquoTernarytransition metal complexes of nitrilotriacetic acid and valineor leucine synthesis and biological applicationsrdquo ChineseJournal of Inorganic Chemistry vol 29 no 9 pp 1969ndash19782013
[40] I M Weiss C Muth R Drumm and H O K Kirchnerldquo(ermal decomposition of the amino acids glycine cysteineaspartic acid asparagine glutamic acid glutamine arginineand histidinerdquo BMC Biophysics vol 11 no 1 2018
[41] A M Petrosyan V V Ghazaryan G Giester and M FleckldquoSulfamates and methanesulfonates of L-arginine and L-his-tidinerdquo Journal of Molecular Structure vol 1163 pp 114ndash1272018
Journal of Chemistry 17
[42] T Kavitha S Haider T Kamal and M Ul-Islam ldquo(ermaldecomposition of metal complex precursor as route to thesynthesis of Co3O4 nanoparticles antibacterial activity andmechanismrdquo Journal of Alloys and Compounds vol 704pp 296ndash302 2017
[43] E M M Ibrahim L H Abdel-Rahman A M Abu-DiefA Elshafaie S K Hamdan and A M Ahmed ldquo(e synthesisof CuO andNiO nanoparticles by facile thermal decompositionof metal-Schiff base complexes and an examination of theirelectric thermoelectric and magnetic Propertiesrdquo MaterialsResearch Bulletin vol 107 pp 492ndash497 2018
[44] S Farhadi M Javanmard and G Nadri ldquoCharacterization ofcobalt oxide nanoparticles prepared by the thermal de-compositionrdquo Acta Chimica Slovenica vol 63 pp 335ndash3432016
[45] E M Zayed E H Ismail G G Mohamed M M H Khaliland A B Kamel ldquoSynthesis spectroscopic and structuralcharacterization and antimicrobial studies of metal com-plexes of a new hexadentate Schiff base ligand Spectropho-tometric determination of Fe(III) in water samples using arecovery testrdquo Monatshefte fur Chemie-Chemical Monthlyvol 145 no 5 pp 755ndash765 2014
[46] V Milacic D Chen L Ronconi K R Landis-PiwowarD Fregona and Q P Dou ldquoA novel anticancer gold(III)dithiocarbamate compound inhibits the activity of a purified20S proteasome and 26S proteasome in human breast cancercell cultures and xenograftsrdquo Cancer Research vol 66 no 21pp 10478ndash10486 2006
[47] T Mosmann ldquoRapid colorimetric assay for cellular growthand survival application to proliferation and cytotoxicityassaysrdquo Journal of Immunological Methods vol 65 no 1-2pp 55ndash63 1983
[48] R L Siegel K D Miller and A Jemal ldquoCancer statistics2018rdquo CA A Cancer Journal for Clinicians vol 68 no 1pp 7ndash30 2018
[49] S Chattopadhyay S P Chakraborty D Laha et al ldquoSurface-modified cobalt oxide nanoparticles new opportunities foranti-cancer drug developmentrdquo Cancer Nanotechnol vol 3no 1-6 pp 13ndash23 2012
[50] F Zielinski V Tognetti and L Joubert ldquoCondensed de-scriptors for reactivity a methodological studyrdquo ChemicalPhysics Letters vol 527 pp 67ndash72 2012
[51] H Wang Y He Q Yan et al ldquoCorrelation between thedielectric properties and biological activities of human ex vivohepatic tissuerdquo Physics in Medicine and Biology vol 60 no 6pp 2603ndash2617 2015
[52] F Tao F Fu F You et al ldquo(e correlation between dielectricproperties and microstructure of femoral bone in rats withdifferent bone qualitiesrdquo Annals of Biomedical Engineeringvol 42 no 6 pp 1238ndash1249 2014
[53] L Gun D Ning and Z Liang ldquoEffective permittivity ofbiological tissue comparison of theoretical model and ex-perimentrdquo Mathematical Problems in Engineering vol 2017Article ID 7249672 2017
[54] E I Ating S A Umoren I I Udousoro E E Ebenso andA P Udoh ldquoLeaves extract of Ananas sativumas greencorrosion inhibitor for aluminium in hydrochloric acid so-lutionsrdquo Green Chemistry Letters and Reviews vol 3 no 2pp 61ndash68 2010
[55] E Hamed ldquoStudies of the corrosion inhibition of copper inNa2SO4 solution using polarization and electrochemicalimpedance spectroscopyrdquo Materials Chemistry and Physicsvol 121 no 1-2 pp 70ndash76 2010
[56] H Zarrok H Oudda A Zarrouk et al ldquoWeight loss mea-surement and theoretical study of new pyridazine compoundas corrosion inhibitor for C38 steel in hydrochloric acidsolutionrdquo Der Pharma Chemica vol 3 no 6 pp 576ndash5902011
18 Journal of Chemistry
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then they were withdrawn from the test solution washedwith deionized water and acetone dried and reweighed(econtainer was placed in a water bath maintained at (303plusmn 1)K (e experiments were operated without (blank) and withthe various concentrations of the mixed ligands and thecomplexes separately (e weight loss was taken as thedifference in weight of the specimen before and after theimmersion time (e experiments were carried out in waterbath with temperature range 293ndash313plusmn 1K
27 Biological Activity (e antimicrobial activity of theprepared ternary metal complexes against two gram-positivebacteria (Streptococcus pneumoniae Bacillis subtilis) twogram-negative bacteria (Pseudomonas aeruginosa Escherichiacoli) and four fungi (Aspergillus fumigates Syncephalastrumracemosum Geotricum candidum Candida albicans) wereinvestigated by a Regional Center for Mycology and Bio-technology (RCMB) Al-Azhar University Cairo
28 Cytotoxicity Cytotoxicity evaluation using viabilityassays was performed by a Regional Center for Mycology ampBiotechnology (RCMB) Al-Azhar University Cairo (einhibitory activity of ternary metal complexes is screenedagainst the cell line hepatocellular carcinoma (HepG-2)
29 Computational Methods Density functional theory(DFT) and its time-dependent extension (TD-DFT) theoryemploying BP86D3DEF2-SVP model and auxiliary basisDEF2JK were carried out using Orca 4012 package [17]Our calculation utilizes the atom-pairwise dispersioncorrection with the BeckendashJohnson damping scheme(D3BJ) [18 19] RI approximation [20] was used Overlap-fitted RIJCOSX approximation was also utilized as a speed-up option leading to enhanced speedups [21 22] withalmost no loss of accuracy [23] First we ran a geometryoptimization and frequency job using BP86D3DEF2-SVP)and auxiliary basis def2J [18 19] All frequency modes arereal indicating that the equilibrium geometry is reachedWe used the same model for EPR simulations of thedoublet state In the case of UV-Vis computations weutilized different models including CAM-B3LYP functionalwithout returning a satisfactory result matching the ex-perimental results (e most successful one that producedresult in excellent agreement with the experiment wasBP86D3DEF2-SVP [18ndash20] and utilizing def2J auxiliarybasis We utilized SMD solvation model [24] Spartan 16parallel package (httpswwwwavefuncom) has beenused to obtain the potential energy surfaces (PESs) at theωB97X-D6-31G(D) level of the DFT
A Broadberry workstation (40 cores) (UK) and a MacPro (12 core) workstation were used
3 Results and Discussion
31 Structure and Spectroscopic Properties Elemental ana-lyses (C H N and metal) and physical and chemicalproperties of the prepared ternary complexes are given in
Table 1 where (1) [ComiddotGlumiddotArgmiddot(H2O)2]middot05H2O (2)[NimiddotGlumiddotArgmiddot(H2O)2]middot05H2O (3) [CumiddotGlumiddotArg]middotH2O and(4) [ZnmiddotGlumiddotArgmiddot(H2O)2]middotH2O
(e thermal decomposition of these complexes in therange (511ndash603K) indicates thermal stability (e effer-vescence test with sodium carbonate confirmed that all theprepared complexes are containing free acidic proton (emagnetic moments molecular weight (Mol wt) and molarconductivity values are given in Table 1 (e pH valuesindicate slightly acidic character (e obtained experimentaland theoretical data confirm the suggested structures shownin Figures 1 and 2
(e paucity of information about mixed amino acids(glutamic acid and arginine) metal complexes motivated usto investigate their molecular structures using DFT theory tocharacterize structural and electronic properties consideringCo(II) and Cu(II) Glu-Arg complexes in aqueous solution asrepresentative of all complexes Optimized geometries aredepicted in Figure 1 Such knowledge is likely to providesome help in the rational design of new complexes for theirbiological importance
In this pH range glutamic acid and L-arginine arepredominantly present in their zwitter ion form and eachhas two coordination sites (one N and one COOminus) which areagreed with their distribution coefficients [24] (e analysisand optimized geometry computations suggested that Nithe important vibrational frequencies of arginine glutamicacid and their ternary metal complexes bands (II) andZn(II) complexes are of distorted octahedral structuresimilar to Co(II) complexes Based on 10Dq values of theseternary complexes the distorted octahedral structure issuggested for nickel cobalt and zinc complexes and squareplanar for copper complex Moderate conductivity mea-sured confirms the existence of intramolecular hydrogenbonds Also magnetic moments of the synthesized com-plexes have been measured in order to confirm theirstructures (e data are presented in Table 1
311 IR Spectra (e important vibrational wavenumbers ofarginine glutamic and their ternary metal complexes bandsare listed in Tables 2 and 3 Arginine showed bands at 1698and 1409 cmminus1 assigned for asymmetric and symmetricstretching vibrations of the carboxylate moiety It also showedmedium broadband at 3086 cmminus1 which attributed to theamino NH2 group (e IR spectra of the complexes did notshow any free carboxylic beaks due to strong intramolecularhydrogen bonding Also IR spectra of the four complexesexhibit crowded region between 3500 and 3000 cmndash1 whereH2O ndashOH and ndashNH stretching modes are expected to ab-sorb (e broadband in the range 3300ndash3400 cmndash1 could beattributed to the intramolecular hydrogen bonding(O HndashO O HndashN OndashH N) An example of the IRspectrum is given in Figure 1S Similarly glutamic acid IRspectra (Figure 3S) showed two bands at 1641 1418 and3062 cmminus1 as reported before [25 26]
Upon complexation the NH stretching wavenumber isshifted to 3141ndash3184 cmminus1 indicating that the amino ni-trogen groups are coordinated to the metal atom [27]
Journal of Chemistry 3
Figure 1 (e optimized structure of Co(II) and Cu(II) complexes (dotted lines represent H bonding) indicating the coordination sites ofthe ligands which result in the most stable orientation Ni and Zn complexes have geometries similar to Co complexes
Figure 2 Optimized geometry around the central transition metal ions showing different bond lengths and angle
Table 2 Experimentally and theoretically simulated IR spectra (in cmminus1) of the studied complexes Assignment of experimentally measuredIR key modes
(e C-NH2 stretching bands of the guanidyl group ofalpha amino group have shifted from 1242 to 1175 cmminus1 ofglutamic acid and L-arginine with respect into (1122ndash1131)cmminus1 of the prepared metal complexes In opposite situationarginine has been shown to have two bands observed at 1586and 1608 cmminus1 due to the asymmetrical vibrations of theC-NH2 bonds of the guanidino group which is protonatedto give the guanidinium form without a significant change incase of complexation [28]
(e asymmetrical (υCOOasy) and symmetrical(υCOOsy) carboxylic groups are shifted in the preparedcomplexes to higher or lower values than their values inligands case as shown in Tables 2 and 3 and also thedifference between these bands are more than 200 cmminus1 inall the prepared metal complexes which indicated that thedeprotonated carboxylic groups in both ligands act asmono dentate groups
All the prepared complexes exhibited bands in the rangeof 3340ndash3472 cmminus1 of υ(OH) signifying that H2O moleculesexist in these complexes [29 30]
(e new confirmed bands only appear in the fourprepared complexes at 538ndash572 cmminus1 and 412ndash456 cmminus1which are assigned to υ(M-O) and υ(M-N) stretching bandsrespectively [31]
(e optimized geometry of the complexes shows dis-torted overall octahedral (or better the square pyramidalC4v-local symmetry of Co(II) ion) for the Co(II) complexand the slightly distorted square planar coordination of theCu(II) ion in the Cu(II) complex Ni and Zn complexes areof similar geometry to the Co complexes Figure 3 shows thatthe local symmetry of both centrosymmetric cations isnoticeably distorted with different M(II)-O and M(II)-Nbond lengths and bond angles indicated in Figure 2
(e simulated PES maps [32] which shed light on thebinding sites of the complexes are depicted in Figure 3Inspection of Figure 3 shows that Co(II) complex exhibits
larger positive potentials (299 kJmol) than Cu(II) complexwhich bears enhanced negative potential than that on Co(II)complex (the difference between negative and positive po-tential energy limits (Delta) PES 24 and minus9 kJmol forCo(II) and Cu(II) complexes respectively) (us Cu(II)complex could act as nucleophile whereas Co(II) complex isof enhanced electrophilic nature during interactions
312 Mass Spectra (e mass spectra of the four complexeswere recorded and provided good evidence and confirma-tion of the molecular weight of these complexes (molecularion peaks (MIPs) are detected under severe experimentalconditions [16] which results in of splitting of crystallinewater) (Figure 2S shows the mass spectrum of Zn(II)complex as example)
313 UV-Vis Absorption Spectra Figure 4 shows the the-oretical and experimental UV-Vis spectra of Co(II) andCu(II) as examples (e results confirm that 1 2 and 4complexes have almost tetragonal distorted octahedralstructure (C4v-local symmetry) with different distortiondegrees which is obvious from the wavenumber and 10Dqvalues of the complexes compared to their literature values[33] Cu complex exhibits slightly distorted square planarshape Table 4 shows electronic spectral data and ligand fieldparameters such asDq B (free ion) B (complex) and β usingband-fitting equation [34 35]
(e value of Racah parameter B (free ion) is larger thanthat of B (complex) due to the covalence bonding of thecomplex (e value of β (nephelauxetic ratio)lt 1 is calcu-lated according to equation (1) βlt 1 validating octahedralgeometry [34 35]
β B(free ion)
B(complex) (1)
Table 3 Experimentally and theoretically simulated IR spectra (in cmminus1) of the studied complexes Assignment of theoretically calculated IRkey modes for Co(II) and Cu(II) complexes in the gas phase Excellent match between experimentally determined and theoreticallycomputed IR modes in case of Ni and Zn complexes is obtained
Complex υ (OH) υ (COO) υ (M-O) υ (M-N)
[Co(glu)(arg)(H2O)2]middotH2O2513 (H-bonded H2O and O of COO of Gu) 16848 (Ar) 5543 46363521 1740 (Gu)
Spectral data and assignments are summarized inTable 4
10Dq for the nickel complex was determined by twoprocedures [34]
(e first one is by solving equations (2) and (3) using theenergy terms of the different triplet states transitions sup-plied for Ni(II) [34] as shown in Table 4
(en applying the trial and error procedure a value for∆ that fits in equations (2) and (3) was found to be10935 cmminus1 which suggested the octahedral structure (esecond method for calculating 10Dq used Tanabe andSugano diagrams for the different metal ion complexesFrom Ni(II) diagram we could be able to deduce the ex-pected positions of the (3A2g⟶ 3T2g) and the(3A2g⟶ 3T1g) transitions (is method corresponds to a
pure crystal field approach and assumes that the value ofthe free ion Racah parameter (B) is maintained in thecomplex
Applying this procedure and considering the ratio of ]1]2 1582225641 062 the best vertical line which fulfilsthis ratio cuts the ∆B axis at a value of 139 and Bcomplexis calculated by equation (4) We found the value765273 cmminus1
299
ndash275
299
ndash275
(a)
272
ndash272
272
ndash272
(b)
Figure 3 PES maps (a) Co complex (upper pan solid surfaces and lower pan clipped surfaces) and legend color codes given in kJmol(b) Cu complex (upper pan solid surfaces and lower pan clipped surfaces)
(4) mdash mdash 221 ]1 45249 Charge transfer mdash mdash
Tetragonal distortionpseudosquarepyramidal
(distorted octahedral)
Journal of Chemistry 7
Bcomplex 2v21 + v22 minus 3v1v2( 1113857
15v2 minus 27v1( 1113857 (4)
(en 10Dq 10637253 cmminus1 is compared to the value of10935 cmminus1 obtained by the first method and both valuesconfirm octahedral structure [34] (e magnetic moment ofthe nickel complex was 31 which also confirmed octahedralstructure [16]
Racah parameters for Co(II) complex is also calculatedsimilarly
Furthermore Co(II) complexes have the effectivemagnetic moment μeff 413 (is value is higher than spinonly moment for three unpaired electrons 389 due to aconsiderable orbital contribution [34 36]
(e Zn complex did not show any d-d transitions butdisplayed charge transfer bands as shown in Table 4 (eexistence of charge transfer was due to transition betweentwo different principle quantum numbers from three to fouras distorted tetrahedron being completed by two watermolecules and forms zinc octahedral complex [34ndash37]
(e longest wavelength weak peaks are observed at516 nm (ε middotM 206 Lmiddotmolminus1middotcmminus1) and 636 nm (ε middotM
179 Lmiddotmolminus1middot cmminus1) for Co(II) and Cu(II) complexes re-spectively (e use of TD-DFT at BP86 DEF2-SVP andauxiliary basis DEF2JK level in water (using SMD solvationmodel) [24] results in λmax Co 5291 nm (oscillatorstrength f 0003) and λmax Cu 6486 nm (f 00256)which are in excellent agreement with the experimentalresults
(e computed natural transition orbitals of the longestwavelength transitions in both complexes reveal the largest(greater than 82) contribution of beta HOMO-LUMOwith minor (about 108) contribution of alpha HOMO-LUMO in case of Co(II) complex and about 992 con-tribution from the beta-HOMO-LUMO in case of Cu(II)complex MOs involved in the electronic transitions aredepicted in Figure 5 which illustrate clear dxz or dyz(e)⟶ dz2 (a1) transition in the local square pyramidal(C4v) of Co(II) ion in the Co(II) complex Metaldxy(b2g)minus dx2 minusy2(b1g) transition is dominant in case oflocal square planar symmetry of the Cu(II) complex (is isapproved by low molar absorptivity experimentally ob-served in the UV-Vis spectra of both complexes andsupported by low value of the computed oscillatorstrengths of the forbidden d-d transitions which acquiresome allowness due to geometry distortion of bothcomplexes
314 ESR Spectra For elucidation of the geometry of thecopper ternary complex ESR measurement gives veryuseful information about the stereo chemistry bondingbetween copper and ligands Figure 1S shows the ESRspectrum of the copper complex with a comparativeadvantage and axial symmetry (g || (parallel) 210748g (perpendicular) 201232 (204984) (ese valuesconfirm square planar coordination in which g || gt g gt 2so the unpaired electron found in the dx2 minus y2 orbital andthe ground state is 2B1g [38] (e observed and calculated
g values are different from ge 20023 due to spin-orbitcoupling (e computed g components are not equalreflecting anisotropic effect and the value of g changes as afunction of the orientation of the molecule relative to theexternal magnetic field (is value is close to the spin onlyvalue and it is in a fair agreement with the computed electronspin only value of ge(computed) 20498 [38] Co(II) com-plex is characterized by g 21280 (e simulated EPRspectrum of Co(II) complex returns ge value of 21085
Different values of Mulliken spin density are shown inFigure 4S in such metal-chelates point to purely anisotropiccouplings (e unpaired electron is totally localized onCo(II) ion In case of Cu(II)-complex electron spin pop-ulation is more distributed with about 46 on the Cu(II)ion(is may result in the simulated significant HF couplingin the case of chelating atoms around Cu(II) ion (e datapoint to mixed copper-nitrogen and copper-oxygen bondsin agreement with the computed optimized geometry [38]
32 +ermal Analysis (ermogravimetric analysis (TGA)for the all prepared ternary metal complexes was carried outin nitrogen atmosphere (e thermal decomposition of thefour complexes displayed similar patterns as their ligands
It is well known that amino acids exist only in solid stateso their thermal decomposition has been endothermal be-tween minus72 and minus151 kJmol when heating in range between185degC and 280degC (eir thermal decomposition releasesthree gases mainly H2O less NH3 and hardly any CO2TGA gives the weight of these gases as weight loss calcu-lations which evolve in appreciable amount [39]
Also the thermal decomposition of L-arginine-dopedKDP potassium dihydrogen phosphate crystal started to loseweight with temperature from 341K to 393K releasedammonia and water molecules gases [40]
(e amino acids are totally broken within the range603ndash793K as shown in Figure 6 and Table 5 (e first stepsare weight loss of the three gases H2O NH3 and CO2 withintemperature range about sim423ndash623K (e hydrocarbonsmatter loses weight in the temperature range sim350ndash520degC(e residues for these complexes are mixture with differentratios of metal and metal oxide above temperature range643ndash793K
It is noteworthy to mention that the geometries of thestudied complexes are similar to L-arginine metal complexreported before [41] which have been confirmed by X-raycrystallographic data of single crystals
33 Nanosized Metal Oxides Characterization
331 XRD of Nano CuO and Nano Cobaltosic Oxide(Co3O4) XRD of thermal synthesized copper oxide nano-particles starting from copper glutamic arginine-mixed li-gands complex gives characteristic peaks at 2θ 326deg 356deg387deg 489deg 536deg 582deg 616deg 663deg and 681deg for the markedindices of (110) (002) (111) (202) (020) (202) (113) (022)and (113) respectively as shown in Figure 7(a) which iscomparable with the literature values (e average primaryparticle size of the copper(II) oxide nanoparticles was
8 Journal of Chemistry
TG (m
g)
80
60
40
20
DTG
(mgmiddot
min
ndash1)
000
ndash020
ndash040
ndash060
ndash080
Weight loss ndash1925mgndash24174
Weight loss ndash1745mgndash21914
Weight loss ndash1366mgndash17154
Weight loss ndash0710mgndash8916
Weight loss ndash0276mgndash3466
273 473 673 873 1073 1273Temperature (K)
(a)
273 473 673 873 1073 1273Temperature (K)
TG (m
g)
100
50
DTG
(mgmiddot
min
ndash1)
000
ndash020
ndash040
ndash060
Weight loss ndash1890mgndash14111 Weight loss ndash8641mg
ndash64514
(b)
Figure 6 Continued
Alpha HOMO Alpha LUMO
Beta HOMO Beta LUMO
(a)
Alpha HOMO Alpha LUMO
Beta HOMO Beta LUMO
(b)
Figure 5 Frontier MOs of (a) Co(II) complex and (b) Cu(II) complex involved in the longest wavelength electronic transition Surfacessimilar to that of Co complex are obtained in case of Ni (ere are no d-d transitions in Zn complexes
Journal of Chemistry 9
Table 5 (ermogravimetric analysis decomposition data for the metal ternary complexes
Complexes Mol (wt) TG range (degC) Mass loss () found (calculated) Total mass loss () Assignment
Figure 6 TG and DTG of (a) [Co(glu)(arg)(H2O)2]middot05H2O (b) [Ni(glu)(arg)(H2O)2]middot05H2O (c) [Cu(glu)((arg)]middotH2O and(d) [ZnmiddotGlumiddotArgmiddot(H2O)2]middotH2O
10 Journal of Chemistry
estimated using well-known DebyendashScherrer formula usingthe full width at half maximum (FWHM) of the (111) peaksin the XRD K(α) is the wavelength of X-ray source(15406 A 015406 nm) β∆θ is the full width at halfmaximum (FWHM 01378) and θ 387 is the diffractionangle corresponding to the lattice plane (111) which gives Dsim143ndash204plusmn 08 nm patterns [42ndash44]
(e pattern of XRD for cobalt oxide nanoparticles showscharacteristic peaks at 2θ values at 1898deg 3127deg 3682deg3848deg 4478deg 5568deg 5934deg 6521deg and 7731deg which arecorresponding to their indices (111) (220) (311) (400) (511)and (440) in agreement with JCPDS Card No 76ndash1802 (ispattern confirms the phase formation of cobalt oxidenanoparticle Figure 7(b) (e average size of the Co3O4particles was calculated by the DebyendashScherrer equationDK(α) λ(β cos θ) whereD is the average crystalline size λ isthe wavelength of CuKα θ is Braggrsquos angle and β is the fullwidth at half maximum (FWHM) of the diffraction peak (eaverage dimension D is sim147ndash182plusmn 06 nm at 2θ 3682degwhich is the intense peak [44]
332 EDX of Nano CuO (e synthesized nano copperoxide is confirmed by the EDX spectrum and SEM imagemeasurement shown in Figure 8 which confirms the highestformation percent of CuO and traces of copper carbide (eSEM image for nano copper oxide CuO shows a mixingnanosize 270sim1079 nm [42 43]
333 EDX of Nano Cobaltosic Oxide (e synthesized nanocobalt oxide is confirmed by the EDX spectrum measure-ment shown in Figure 9 which confirms the highest for-mation percent of cobaltosic oxide Co3O4 and traces ofcobalt carbide (e SEM image for nano cobaltosic oxideCo3O4 shows a mixing nanosize 318ndash8543 nm
34 Applications
341 Biological Activity Mixed ligand ternary complexeshave been examined for their in vitro antimicrobial activity(is investigation was performed using the diffusion agartechnique (Figure 5S) (e assays collection included
g-negative (Pseudomonas aeruginosa RCMB 010043 andEscherichia coli RCMB 010052) pathogenic bacteria usingGentamicin 5mgml as a reference compound and g-pos-itive (Streptococcus pneumoniae RCMB 010010 and Bacillissubtilis RCMB 010067) pathogenic bacteria using Ampi-cillin 5mgml as a reference compound It was also in-cluded four fungi (Aspergillus fumigatus RCMB 02568Syncephalastrum racemosum RCMB 05922 Geotrichumcandidum RCMB 05097 and Candida albicans RCMB05036) using Amphotericin B 5mgml as a referencecompound [30 45]
(e inhibitory effects of the used ligands and theirternary polymer complexes against the used organisms aregiven in Table 6 In general the used ligands did not displayantifungal or antibacterial inhibitory
For antifungal assay examination and based on theminimum inhibitory concentration (MIC) values it is foundthat the inhibitory effect of all the ternary complexes varyfrom moderate to weak against Amphotericin B controlexcept in the case of Candida albicans (RCMB 05036) whichis not affected by both cobalt and zinc complexes
(e antibacterial activities of the obtained ternarycomplexes are determined in terms of MIC values As shownin Table 6 all complexes display moderate activities againstStreptococcus pneumonia (RCMB 010010) and Bacillis sub-tilis RCMB 010067 (e growth of the gram-negative bac-teria Pseudomonas aeruginosa RCMB 010043 andEscherichia coli RCMB 010052 is extremely affected by bothcopper and nickel complexes which display strong inhibitionagainst the gram-negative pathogenic bacteria with MICvalue less than the Gentamicin control (e remainingcomplexes do not display the same behavior during theassay
342 Cytotoxicity One of the fundamental goals in me-dicinal chemistry is the development of new anticancer andantimicrobial therapeutic agents Cancer treatment usingmetal-based drugs is one of the very effective strategies as themetal ions are capable of binding to nucleic acids stereo-specifically with varying strength
In vitro anticancer activity evaluation of the newlysynthesized compounds was carried out against human
Cou
nts
400
300
200
100
010 20 30 40
Angles (deg2θ)50 60 70
(a)
Cou
nts
100
50
010 20 30 40
Angles (deg2θ)50 60 70
(b)
Figure 7 XRD pattern of (a) copper oxide CuO and (b) cobalt oxide Co3O4 prepared by thermal decomposition at 550Cdeg starting frommetal glutamic arginine mixed ligands complex
Journal of Chemistry 11
cancer cell lines hepatocellular carcinoma (HePG2) becauseliver cancer is the third most common cause of death incancer using MTT method [26 46 47]
Doxorubicin HCl is one of the most effective anti-cancer agents is used as a reference drug in this study (eobtained results from Table 2S indicated that most of thesemoleculesrsquo behavior can be observed from the values of the
half maximal inhibitory concentration IC50 whichfor glutamic and arginine are 167 and 376 μgmlrespectively
IC50 results indicate that the ternary complexes havepromised inhibition of HePG2 liver tumors [48 49]
Cell viability was assessed by themitochondrial-dependentreduction of yellow MTT (3-(45-dimethylthiazol-2-yl)-25-
108K096K084K072K060K048K036K024K012K000K
000 100 200 300 400 500 600 700 800 900
Cu Kβ
Cu Kα
Cu L
O KC K
(a) (b)
Figure 8 EDX and SEM images of CuO obtained by thermal decomposition at 550Cdeg starting from copper glutamic arginine mixed ligandscomplex
135K120K105K090K075K060K045K030K015K000K
000 100 200 300 400 500 600 700 800 900
O K
Co L Co Kα
Co Kβ
(a) (b)
Figure 9 EDX and SEM images of Co3O4 obtained by thermal decomposition at 550Cdeg starting from cobalt glutamic arginine mixedligands complex
Table 6 Antimicrobial activity of prepared ternary metal complexes
Sample tested microorganisms Glutamicacid L-arginine (1) (2) (3) (4) Standard
lowastNA no activity Values in bracket are the MIC values
12 Journal of Chemistry
diphenyl tetrazolium bromide) to insoluble purple formazan[45] (e prepared ternary metal complexes are of differentviability percentages as depicted in Figure 10 Data of bothligands are also included for comparison
Table 2S shows that the ligands have lower inhibition ofHePG2 than their metal ternary complexes (e coppercomplex introduces the highest inhibition
Additionally Table 7 summarizes some computedelectrical reactivity [50] and thermodynamic propertiesfor Co(II) and Cu(II) complexes (as maximum andminimum IC50 of the four prepared ternary metalscomplexes) which are correlated with the inhibition ofhuman cancer cells and are useful to explain the roleplayed by molecular properties in inhibition of humancancer cells
(e simulated data summarized in Table 7 conclude thefollowing
(i) Cu complex is more energetically stable relative toCo complex by about minus265 kJmol
(ii) Cu complex is characterized by lower dipole mo-ment and lower polarizability relative to Co(II)complexes
(iii) Enthalpy and Gibbs free energy of the Cu complexesare more stable by about minus265 kJmol relative toCo(II) complex Lower entropy reflects lower degreeof randomness of Cu(II) complex
(iv) (e chemical potential (μprime) (negative of molecularelectronegativity) of Cu(II) complex is much higherthan that of Co(II) complex reflecting the enhancedreactivity of Cu(II) complex as nucleophile becauseμprime measures the escaping tendency of electrons fromthe complex (μprime (LUMO+HOMO)2) [50]
(v) Cu complex is characterized by lower hardness thanCo(II) complex Hardness measures the resistanceto electron transfer (η (LUMO-HOMO)2) [50]
It seems that more thermodynamically stable and lesspolar Cu complex exhibits that enhanced responsive elec-tron cloud transfer to the surrounding tumor relative to theCo(II) complex (ese quantitative molecular descriptors[50] explain the promising inhibition activity of the Cu(II)complex (e results are correlated with the above-discussedPES results which show that Cu complex could act asnucleophile whereas Co complex is of enhanced electro-philic nature
(e nucleophilicity of Cu complex (seeking for positivelycharged sites of the reactant) together with its electricalthermodynamic and molecular properties favors its prom-ising inhibition activity towards HePG2 cancer cell [51ndash53]
343 Corrosion Inhibition of Aluminum An assessment ofcorrosion rates and inhibition efficiency for aluminum withdifferent inhibitor concentrations were computed as followscorrosion rate Rcorr was computed using equation (5)
Rcorr M1 minusM2( 1113857(mg)
A cm2( ) times t(h) (5)
where M1 weight (g) before immersion M2 weight (g)after immersion A area (cm2) of the specimen andt exposure time (h)
(e inhibition efficiency (IE) was evaluated usingequation (6)
IE Rblank minusRinh
Rblank1113890 1113891 times 100 (6)
120
60
100
80
60
40
20
00 10 20 30 40 50
GlutamicLarginineCu(II)
Ni(II)Co(II)Zn(II)
Figure 10 Cell viability of (HePG2) at different concentrations of ligands and the prepared metal complexes
Table 7 Simulated electrical properties of complexes studied exhibiting enhanced inhibition of HePG2
where Rblank corrosion rates in the absence of inhibitor andRinh corrosion rates in the presence of inhibitor [16]
Table 8 shows the calculated corrosion rates and inhibitionefficiencies of aluminum specimens in aqueous solution of 1MHCl as the corrosive medium in absence and presence ofmixed ligands and their ternary metal complexes at differenttemperatures (293 ndash313) K for 7 hours of each concentrationFigure 6S shows that as the concentration of ligands and theircomplexes increases Rcorr decreases and IE increases formixed ligands and their metal complexes acted as more ef-ficient inhibitors than their mixed ligands alone
344 Adsorption Isotherms and the +ermodynamic Acti-vation Parameters (e metal surface coverage degree(θIE100) was subjected to different adsorption iso-therms (e well fit for weight loss data is obtained forLangmuir adsorption isotherm Figure 11
Table 8 Corrosion parameters for aluminum in aqueous solution of 1M HCl in the absence and presence of different concentrations ofmixed ligands and their metal complexes at different temperatures for 7 hrs
Inhibitors C (times10minus2M)Corrosion rate times10minus4
Figure 11 Langmuir adsorption isotherms of the mixed ligands(L) and their metal complexes
14 Journal of Chemistry
(e temperature effect (293ndash313 K) on aluminum weightloss inhibition may be attributed to two main mechanismsphysical and chemical adsorption [37] (e suggested mech-anisms are obtained as the temperature increases the efficiencydecreases for mixed ligands but increases for their metalcomplexes depending on the nature of bond formation be-tween the mixed ligands and aluminum surface which isdifferent from the nature of bond formation between metalcomplexes and the aluminum surface [16] Arrhenius equation(7) gives the relation between the corrosion rate andtemperature
lnRcorr lnAminusElowast
RT (7)
where A is the Arrhenius factor Elowast is the apparent activationenergy of the corrosion process R is the rate gas constant andT is the absolute temperature (e straight line slope oflogRcorr vs 1T for aluminum 1M HCl at 4times10minus4molL after7 h is minusElowast2303R for the inhibitors (Figure 12)
(e activation thermodynamic parameters for alumi-num dissolution could be obtained from the transition stateequation (8)
lnRcorr
T1113874 1113875 ln
R
Nh1113874 1113875 +
ΔSlowast
R1113888 1113889minus
ΔHlowast
RT1113888 1113889 (8)
where the entropy of activation ∆Slowast and the apparent en-thalpy of activation ∆Hlowast can be obtained from the intercept
3150
02
04
06
logR
corr
(gmiddoth
ndash1middotcm
ndash1)
08
1
12
32 325 331000T(Kndash1)
335 34 345
BlankMix ligandsZn2+
Co2+Ni2+Cu2+
Figure 12 Arrhenius of log corrosion rate (Rcorr) vs 1T for aluminum in 1M HCl without and with 004times10minus2MLminus1 of inhibitors (mixedligands and their metal complexes)
Table 9 (ermodynamic parameters for the adsorption of (004times10minus2)ML mixed ligands and their metal complexes on aluminum metalin aqueous solution of 1M HCl at different temperatures for 7 hrs
and the slope for the straight line of the relation betweenln(RcorrT) vs (1T) respectively N is Avogadrorsquos numberand h is Planckrsquos constant (e Gibbs free energy of acti-vation ∆Glowast can be detected by equation (9)
ΔGlowast ΔHlowast minusTΔSlowast (9)
Table 9 shows the thermodynamic parameters for theadsorption of mixed ligands and their metal complexes (epositive value of ∆Hlowast indicated the endothermic property ofdissolution process nature for aluminum in the acidicmedium [54]
However the blank ΔHlowast value is higher than the in-hibitor metal complexes which indicated that the inhibitionefficiency generally increases with increasing temperature(e association step is the rate-determining step rather thana dissociation process in presence of the metal complexesinhibitors due to the negative values of ΔSlowast It is known thatthe values of ΔGlowast above 40 kJmiddotmolminus1 are referred to chargetransfer from the inhibitor molecules into aluminum surfaceto form coordinated compound on the Al surface whichblocks it against corrosion process by different degrees Alsothe chemical adsorption process mechanism is confirmed bythe values of ΔGlowast above 40 kJmiddotmolminus1 [16 54ndash56]
4 Conclusions
Novel coordination materials of ternary divalent metalions (Cu(II) Ni(II) Co(II) and Zn(II)) chelated by thebidentate glutamic acid (Glu) and L-arginine (Arg) aminoacids are synthesized and characterized (e metal ionscomplexes are modelled using density DFT and TD-DFTtheory Computed molecular and spectroscopic (IR UV-Vis and EPR) properties validated the experimental re-sults (e used computational methods are capable ofproviding good structural descriptions for the TM com-plexes Consistent with the experimental properties theoptimized structures of the complexes [Cu(II) Glu-Arg]and [Co(II) Glu-Arg (H2O)2] reveal that symmetry en-vironment of Cu(II) exhibits slightly distorted squareplanar shape whereas Co(II)-complex has a distortedoctahedral (where Co(II) central ion is of C4v-localsymmetry) Spectral properties of [Ni(II) Glu-Arg(H2O)2] and [ZnmiddotGlumiddotArgmiddot(H2O)2] complexes indicatethat they have similar structure as Co(II) complex All thestudied ternary metal complexes are of different anti-fungal activities ranging from moderate to weak withoutpractically noticed inhibitory effects whereas antibacte-rial activities of all studied metal complexes show sig-nificant effects
Cytotoxicity studies against (HePG2) reveal the prom-ising potentiality of Cu(II) complex as inhibitor of cancercells(e results are correlated with the computed moleculardescriptors including dipole moment polarizability ther-modynamics and reactivity properties as well as the PESmaps
(e corrosion inhibition of aluminum metal specimensin 1M HCl is efficiently achieved by mixed ligands and theirmetal complexes studied
Data Availability
(e data used to support the findings of this study areavailable from the corresponding author upon request
Conflicts of Interest
(e authors declare that they have no conflicts of interest
Supplementary Materials
(e supplementary materials consist of six figures and twotables to further clarify the structures and trends of the newlyprepared metal ternary complexes (SupplementaryMaterials)
References
[1] Z Ozturk D A Kose A Asan et al ldquoPorous metal-organicCu(II) complex of L-Arginine 2synthesis characterizationhydrogen storage properties and molecular simulation cal-culationsrdquo Hittite Journal of Science and Engineering vol 1no 1 pp 1ndash5 2014
[2] S A Lahsasni R A Ammar M F Amin et al ldquoMixed-ligandcomplex formation of Cu(II) with 12- diphenylethylenedi-amine as primary ligand and amino acids as secondary li-gandsrdquo International Journal of Electrochemical Sciencevol 7 pp 7699ndash7711 2012
[3] H Sigel B P Operschall S S Massoud B Song andR Griesser ldquoEvidence for intramolecular aromatic-ringstacking in the physiological pH range of the mono-deprotonated xanthine residue in mixed-ligand complexescontaining xanthosinate 5prime-monophosphate (XMP)rdquo DaltonTransactions vol 46 no 46 pp 5521ndash5529 2006
[4] S Udhayakumar K G Shankar S Sowndarya S VenkateshC Muralidharan and C Rose ldquol-Arginine intercedes bio-crosslinking of a collagen-chitosan 3D-hybrid scaffold fortissue engineering and regeneration in silico in vitro and invivo studiesrdquo RSC Advances vol 7 no 40 pp 25070ndash250882017
[5] P K Datta M Chandra and A K Dey ldquoTernary complexesof copper(II) nickel(II) and zinc(II) with nitrilotriacetic acidas a primary ligand and some phenolic acids as secondaryligandsrdquo Transition Metal Chemistry vol 5 no 1ndash3 1980
[6] J S Woertink L Tian D Maiti et al ldquoSpectroscopic andcomputational studies of an end-on bound superoxo-Cu(II)complex geometric and electronic factors that determine theground staterdquo Inorganic Chemistry vol 49 no 20pp 9450ndash9459 2010
[7] S Dutta S Ray K Nagarajan et al ldquoGlutamic acid analoguesused as potent anticancer a reviewrdquo Der Pharma Chemicavol 3 no 2 pp 263ndash272 2011
[8] T Sismanoglu S Pura and A Bastug ldquoBinary and ternarymetal complexes of Congo red with amino acidsrdquo Dyes andPigments vol 70 no 2 pp 136ndash142 2006
[9] R N Patel H C Pandey K B Pandeya et al ldquoMixed ligandcomplex formation of nickel(II)copper(II) and zinc(II) withsome amino acids and imidazolesrdquo Indian Journal ofChemistry-Section A Inorganic Physical +eoretical andAnalytical Chemistry vol 38 no 8 pp 850ndash853 1999
[10] L Meng and Z Lin ldquoComplexations of alkalialkaline earthmetal cations with gaseous glutamic acidrdquo Computational and+eoretical Chemistry vol 1039 pp 1ndash10 2014
16 Journal of Chemistry
[11] L D Pinto P A L Puppin V M Behring O C AlvesN A Rey and J Felcman ldquoSolution and solid state study ofcopper(II) ternary complexes containing amino acids of in-terest for brain biochemistry-2 homocysteine with aspartateglutamate or methioninerdquo Inorganica Chimica Acta vol 386pp 60ndash67 2012
[12] A Wojciechowska A Ggor and W Zierkiewicz ldquoChiraloctahedral complexes of Co(III) as catalysts for asymmetricepoxidation of chalcones under phase transfer conditionsrdquoRSC Advances vol 5 no 46 pp 36295ndash36306 2015
[13] B M Weckhuysen A A Verberckmoes L Fu andR A Schoonheydt ldquoZeolite-encapsulated copper(II) aminoacid complexes synthesis spectroscopy and catalysisrdquo Journalof Physical Chemistry vol 100 no 22 pp 9456ndash9461 1996
[14] K Y El-Baradie N A El-Wakiel and H A El-GhamryldquoSynthesis characterization and corrosion inhibition in acidmedium ofl-histidine Schiff base complexesrdquo Applied Or-ganometallic Chemistry vol 29 no 3 pp 117ndash125 2015
[15] S S R Anthony and R Susai ldquoInhibition of corrosion ofcarbon steel in well water by arginine-Zn2+ systemrdquo Journal ofElectrochemical Science and Engineering vol 2 no 2pp 91ndash104 2012
[16] E H Isamil F F AlBlewi N Soliman and M M H Khalilldquo(ermal studies and mass loss inhibition for some newmixed amino acid metal complexes with their applicationsrdquoJournal of +ermal Analysis and Calorimetry vol 125 no 1pp 289ndash300 2016
[17] F Neese ldquo(e ORCA program system 4012rdquo Wiley In-terdisciplinary Reviews Computational Molecular Sciencevol 2 no 1 pp 73ndash78 2012
[18] S Grimme S Ehrlich and L Goerigk ldquoEffect of the dampingfunction in dispersion corrected density functional theoryrdquoJournal of Computational Chemistry vol 32 no 7pp 1456ndash1465 2011
[19] S Grimme J Antony S Ehrlich and H Krieg ldquoA consistentand accurate ab initio parametrization of density functionaldispersion correction (DFT-D) for the 94 elements H-Purdquo+e Journal of Chemical Physics vol 132 no 15 article154104 2010
[20] F Weigend ldquoHartree-Fock exchange fitting basis sets for H toRnrdquo Journal of Computational Chemistry vol 29 no 2pp 167ndash175 2008
[21] F Neese F Wennmohs and A Hansen ldquoEfficient ap-proximate and parallel Hartree-Fock and hybrid DFT cal-culations A lsquochain-of-spheresrsquo algorithm for the Hartree-Fock exchangerdquo Chemical Physics vol 356 no 1ndash3pp 98ndash109 2009
[22] R Izsak and F Neese ldquoAn overlap fitted chain of spheresexchange methodrdquo Journal of Chemical Physics vol 135no 14 article 144105 2011
[23] T Petrenko S Kossmann and F Neese ldquoEfficient time-dependent density functional theory approximations forhybrid density functionals analytical gradients and paralle-lizationrdquo Journal of Chemical Physics vol 134 no 5 article054116 2011
[24] A V Marenich C J Cramer and D G Truhlar ldquoUniversalsolvation model based on solute electron density and on acontinuum model of the solvent defined by the bulk dielectricconstant and atomic surface tensionsrdquo Journal of PhysicalChemistry B vol 113 no 18 pp 6378ndash96 2009
[25] S Donovan C Stiefbold and K Sprague ldquoChapter 3Chemical properties of amino acids and identification ofunknown amino acidsrdquo in Proceedings of the 17 thWorkshopConference of the Association for Biology
Laboratory Education (ABLE) vol 17 pp 35ndash70 Bain-bridge GA USA March 1996
[26] C C Wagner J Enrique and C Claudia ldquoVibrational andmagnetic properties of a CuMg glutamate complexrdquoArgentina Acta Farm Bonaerense vol 22 no 2 pp 137ndash1422003
[27] M Arif R Sur and M Arshad ldquoStudies on the thermaldecomposition of copper (II) flouride complexes with variousamino acids in nitrogen atmosphererdquo Turkish Journal ofChemistry vol 25 pp 73ndash79 2001
[28] A Ghosh M J Tucker and R M Hochstrasser ldquoIdentifi-cation of arginine residues in peptides by 2d-IR echo spec-troscopyrdquo Journal of Physical Chemistry A vol 115 no 34pp 9731ndash9738 2011
[29] K Nakamoto Infrared Spectra of Inorganic and CoordinationCompounds Part B Wiley-Interscience New York NY USA5th edition 1997
[30] E Santi M H Torre E Kremer S B Etcheverry andE J Baran ldquoVibrational spectra of the copper(II) and nick-el(II) complexes of piroxicamrdquo Vibrational Spectroscopyvol 5 no 3 pp 285ndash293 1993
[31] H N Aliyu and A S Mohammed ldquoSynthesis spectropho-tometric and biological activity of nickel (II) and copper (II)complexes with schiff base derived from acetylacetone andhistidinerdquo Global Advanced Research Journal of Microbiologyvol 1 no 5 pp 67ndash71 2012
[32] J S Murray and P Politzer ldquo(e electrostatic potential anoverviewrdquo Wiley Interdisciplinary Reviews ComputationalMolecular Science vol 1 no 2 pp 153ndash163 2011
[33] E R Souaya M M H Khalil and E H Ismail ldquoSynthesis andcharacterization of ternary complexes of certain hydroxylacids and their biological applicationsrdquo Research Journal ofPharmaceutical Biological and Chemical Sciences vol 5 no 4pp 18ndash30 2014
[34] N N Greenwood and A Earnshaw A Review of Chemistry ofthe Elements Pergamon Press Oxford UK 1984
[35] V Reddy N Patil and S D Angadi ldquoSynthesis character-ization and antimicrobial activity of Cu(II) Co(II) and Ni(II)complexes with ON and S Donor ligandsrdquo E-Journal ofChemistry vol 5 no 3 pp 577ndash583 2008
[36] F A Cotton G Wilkinson C A Murillo et al Advances inSchiff Base Chemistry Wiley New York NY USA 6th edi-tion 1999
[37] M M H Khalil E H Ismail S A Azim and E R SouayaldquoSynthesis characterization and thermal analysis of ternarycomplexes of nitrilotriacetic acid and alanine or phenylala-nine with some transition metalsrdquo Journal of +ermalAnalysis and Calorimetry vol 101 no 1 pp 129ndash135 2010
[38] F Mabbs and D Colisson Electron Paramagnetic Resonanceof D Transition Metal Compounds Vol 102 ElsevierAmsterdam Netherlands 1992
[39] M M H Khalil E R Souaya E H Ismail et al ldquoTernarytransition metal complexes of nitrilotriacetic acid and valineor leucine synthesis and biological applicationsrdquo ChineseJournal of Inorganic Chemistry vol 29 no 9 pp 1969ndash19782013
[40] I M Weiss C Muth R Drumm and H O K Kirchnerldquo(ermal decomposition of the amino acids glycine cysteineaspartic acid asparagine glutamic acid glutamine arginineand histidinerdquo BMC Biophysics vol 11 no 1 2018
[41] A M Petrosyan V V Ghazaryan G Giester and M FleckldquoSulfamates and methanesulfonates of L-arginine and L-his-tidinerdquo Journal of Molecular Structure vol 1163 pp 114ndash1272018
Journal of Chemistry 17
[42] T Kavitha S Haider T Kamal and M Ul-Islam ldquo(ermaldecomposition of metal complex precursor as route to thesynthesis of Co3O4 nanoparticles antibacterial activity andmechanismrdquo Journal of Alloys and Compounds vol 704pp 296ndash302 2017
[43] E M M Ibrahim L H Abdel-Rahman A M Abu-DiefA Elshafaie S K Hamdan and A M Ahmed ldquo(e synthesisof CuO andNiO nanoparticles by facile thermal decompositionof metal-Schiff base complexes and an examination of theirelectric thermoelectric and magnetic Propertiesrdquo MaterialsResearch Bulletin vol 107 pp 492ndash497 2018
[44] S Farhadi M Javanmard and G Nadri ldquoCharacterization ofcobalt oxide nanoparticles prepared by the thermal de-compositionrdquo Acta Chimica Slovenica vol 63 pp 335ndash3432016
[45] E M Zayed E H Ismail G G Mohamed M M H Khaliland A B Kamel ldquoSynthesis spectroscopic and structuralcharacterization and antimicrobial studies of metal com-plexes of a new hexadentate Schiff base ligand Spectropho-tometric determination of Fe(III) in water samples using arecovery testrdquo Monatshefte fur Chemie-Chemical Monthlyvol 145 no 5 pp 755ndash765 2014
[46] V Milacic D Chen L Ronconi K R Landis-PiwowarD Fregona and Q P Dou ldquoA novel anticancer gold(III)dithiocarbamate compound inhibits the activity of a purified20S proteasome and 26S proteasome in human breast cancercell cultures and xenograftsrdquo Cancer Research vol 66 no 21pp 10478ndash10486 2006
[47] T Mosmann ldquoRapid colorimetric assay for cellular growthand survival application to proliferation and cytotoxicityassaysrdquo Journal of Immunological Methods vol 65 no 1-2pp 55ndash63 1983
[48] R L Siegel K D Miller and A Jemal ldquoCancer statistics2018rdquo CA A Cancer Journal for Clinicians vol 68 no 1pp 7ndash30 2018
[49] S Chattopadhyay S P Chakraborty D Laha et al ldquoSurface-modified cobalt oxide nanoparticles new opportunities foranti-cancer drug developmentrdquo Cancer Nanotechnol vol 3no 1-6 pp 13ndash23 2012
[50] F Zielinski V Tognetti and L Joubert ldquoCondensed de-scriptors for reactivity a methodological studyrdquo ChemicalPhysics Letters vol 527 pp 67ndash72 2012
[51] H Wang Y He Q Yan et al ldquoCorrelation between thedielectric properties and biological activities of human ex vivohepatic tissuerdquo Physics in Medicine and Biology vol 60 no 6pp 2603ndash2617 2015
[52] F Tao F Fu F You et al ldquo(e correlation between dielectricproperties and microstructure of femoral bone in rats withdifferent bone qualitiesrdquo Annals of Biomedical Engineeringvol 42 no 6 pp 1238ndash1249 2014
[53] L Gun D Ning and Z Liang ldquoEffective permittivity ofbiological tissue comparison of theoretical model and ex-perimentrdquo Mathematical Problems in Engineering vol 2017Article ID 7249672 2017
[54] E I Ating S A Umoren I I Udousoro E E Ebenso andA P Udoh ldquoLeaves extract of Ananas sativumas greencorrosion inhibitor for aluminium in hydrochloric acid so-lutionsrdquo Green Chemistry Letters and Reviews vol 3 no 2pp 61ndash68 2010
[55] E Hamed ldquoStudies of the corrosion inhibition of copper inNa2SO4 solution using polarization and electrochemicalimpedance spectroscopyrdquo Materials Chemistry and Physicsvol 121 no 1-2 pp 70ndash76 2010
[56] H Zarrok H Oudda A Zarrouk et al ldquoWeight loss mea-surement and theoretical study of new pyridazine compoundas corrosion inhibitor for C38 steel in hydrochloric acidsolutionrdquo Der Pharma Chemica vol 3 no 6 pp 576ndash5902011
18 Journal of Chemistry
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Figure 1 (e optimized structure of Co(II) and Cu(II) complexes (dotted lines represent H bonding) indicating the coordination sites ofthe ligands which result in the most stable orientation Ni and Zn complexes have geometries similar to Co complexes
Figure 2 Optimized geometry around the central transition metal ions showing different bond lengths and angle
Table 2 Experimentally and theoretically simulated IR spectra (in cmminus1) of the studied complexes Assignment of experimentally measuredIR key modes
(e C-NH2 stretching bands of the guanidyl group ofalpha amino group have shifted from 1242 to 1175 cmminus1 ofglutamic acid and L-arginine with respect into (1122ndash1131)cmminus1 of the prepared metal complexes In opposite situationarginine has been shown to have two bands observed at 1586and 1608 cmminus1 due to the asymmetrical vibrations of theC-NH2 bonds of the guanidino group which is protonatedto give the guanidinium form without a significant change incase of complexation [28]
(e asymmetrical (υCOOasy) and symmetrical(υCOOsy) carboxylic groups are shifted in the preparedcomplexes to higher or lower values than their values inligands case as shown in Tables 2 and 3 and also thedifference between these bands are more than 200 cmminus1 inall the prepared metal complexes which indicated that thedeprotonated carboxylic groups in both ligands act asmono dentate groups
All the prepared complexes exhibited bands in the rangeof 3340ndash3472 cmminus1 of υ(OH) signifying that H2O moleculesexist in these complexes [29 30]
(e new confirmed bands only appear in the fourprepared complexes at 538ndash572 cmminus1 and 412ndash456 cmminus1which are assigned to υ(M-O) and υ(M-N) stretching bandsrespectively [31]
(e optimized geometry of the complexes shows dis-torted overall octahedral (or better the square pyramidalC4v-local symmetry of Co(II) ion) for the Co(II) complexand the slightly distorted square planar coordination of theCu(II) ion in the Cu(II) complex Ni and Zn complexes areof similar geometry to the Co complexes Figure 3 shows thatthe local symmetry of both centrosymmetric cations isnoticeably distorted with different M(II)-O and M(II)-Nbond lengths and bond angles indicated in Figure 2
(e simulated PES maps [32] which shed light on thebinding sites of the complexes are depicted in Figure 3Inspection of Figure 3 shows that Co(II) complex exhibits
larger positive potentials (299 kJmol) than Cu(II) complexwhich bears enhanced negative potential than that on Co(II)complex (the difference between negative and positive po-tential energy limits (Delta) PES 24 and minus9 kJmol forCo(II) and Cu(II) complexes respectively) (us Cu(II)complex could act as nucleophile whereas Co(II) complex isof enhanced electrophilic nature during interactions
312 Mass Spectra (e mass spectra of the four complexeswere recorded and provided good evidence and confirma-tion of the molecular weight of these complexes (molecularion peaks (MIPs) are detected under severe experimentalconditions [16] which results in of splitting of crystallinewater) (Figure 2S shows the mass spectrum of Zn(II)complex as example)
313 UV-Vis Absorption Spectra Figure 4 shows the the-oretical and experimental UV-Vis spectra of Co(II) andCu(II) as examples (e results confirm that 1 2 and 4complexes have almost tetragonal distorted octahedralstructure (C4v-local symmetry) with different distortiondegrees which is obvious from the wavenumber and 10Dqvalues of the complexes compared to their literature values[33] Cu complex exhibits slightly distorted square planarshape Table 4 shows electronic spectral data and ligand fieldparameters such asDq B (free ion) B (complex) and β usingband-fitting equation [34 35]
(e value of Racah parameter B (free ion) is larger thanthat of B (complex) due to the covalence bonding of thecomplex (e value of β (nephelauxetic ratio)lt 1 is calcu-lated according to equation (1) βlt 1 validating octahedralgeometry [34 35]
β B(free ion)
B(complex) (1)
Table 3 Experimentally and theoretically simulated IR spectra (in cmminus1) of the studied complexes Assignment of theoretically calculated IRkey modes for Co(II) and Cu(II) complexes in the gas phase Excellent match between experimentally determined and theoreticallycomputed IR modes in case of Ni and Zn complexes is obtained
Complex υ (OH) υ (COO) υ (M-O) υ (M-N)
[Co(glu)(arg)(H2O)2]middotH2O2513 (H-bonded H2O and O of COO of Gu) 16848 (Ar) 5543 46363521 1740 (Gu)
Spectral data and assignments are summarized inTable 4
10Dq for the nickel complex was determined by twoprocedures [34]
(e first one is by solving equations (2) and (3) using theenergy terms of the different triplet states transitions sup-plied for Ni(II) [34] as shown in Table 4
(en applying the trial and error procedure a value for∆ that fits in equations (2) and (3) was found to be10935 cmminus1 which suggested the octahedral structure (esecond method for calculating 10Dq used Tanabe andSugano diagrams for the different metal ion complexesFrom Ni(II) diagram we could be able to deduce the ex-pected positions of the (3A2g⟶ 3T2g) and the(3A2g⟶ 3T1g) transitions (is method corresponds to a
pure crystal field approach and assumes that the value ofthe free ion Racah parameter (B) is maintained in thecomplex
Applying this procedure and considering the ratio of ]1]2 1582225641 062 the best vertical line which fulfilsthis ratio cuts the ∆B axis at a value of 139 and Bcomplexis calculated by equation (4) We found the value765273 cmminus1
299
ndash275
299
ndash275
(a)
272
ndash272
272
ndash272
(b)
Figure 3 PES maps (a) Co complex (upper pan solid surfaces and lower pan clipped surfaces) and legend color codes given in kJmol(b) Cu complex (upper pan solid surfaces and lower pan clipped surfaces)
(4) mdash mdash 221 ]1 45249 Charge transfer mdash mdash
Tetragonal distortionpseudosquarepyramidal
(distorted octahedral)
Journal of Chemistry 7
Bcomplex 2v21 + v22 minus 3v1v2( 1113857
15v2 minus 27v1( 1113857 (4)
(en 10Dq 10637253 cmminus1 is compared to the value of10935 cmminus1 obtained by the first method and both valuesconfirm octahedral structure [34] (e magnetic moment ofthe nickel complex was 31 which also confirmed octahedralstructure [16]
Racah parameters for Co(II) complex is also calculatedsimilarly
Furthermore Co(II) complexes have the effectivemagnetic moment μeff 413 (is value is higher than spinonly moment for three unpaired electrons 389 due to aconsiderable orbital contribution [34 36]
(e Zn complex did not show any d-d transitions butdisplayed charge transfer bands as shown in Table 4 (eexistence of charge transfer was due to transition betweentwo different principle quantum numbers from three to fouras distorted tetrahedron being completed by two watermolecules and forms zinc octahedral complex [34ndash37]
(e longest wavelength weak peaks are observed at516 nm (ε middotM 206 Lmiddotmolminus1middotcmminus1) and 636 nm (ε middotM
179 Lmiddotmolminus1middot cmminus1) for Co(II) and Cu(II) complexes re-spectively (e use of TD-DFT at BP86 DEF2-SVP andauxiliary basis DEF2JK level in water (using SMD solvationmodel) [24] results in λmax Co 5291 nm (oscillatorstrength f 0003) and λmax Cu 6486 nm (f 00256)which are in excellent agreement with the experimentalresults
(e computed natural transition orbitals of the longestwavelength transitions in both complexes reveal the largest(greater than 82) contribution of beta HOMO-LUMOwith minor (about 108) contribution of alpha HOMO-LUMO in case of Co(II) complex and about 992 con-tribution from the beta-HOMO-LUMO in case of Cu(II)complex MOs involved in the electronic transitions aredepicted in Figure 5 which illustrate clear dxz or dyz(e)⟶ dz2 (a1) transition in the local square pyramidal(C4v) of Co(II) ion in the Co(II) complex Metaldxy(b2g)minus dx2 minusy2(b1g) transition is dominant in case oflocal square planar symmetry of the Cu(II) complex (is isapproved by low molar absorptivity experimentally ob-served in the UV-Vis spectra of both complexes andsupported by low value of the computed oscillatorstrengths of the forbidden d-d transitions which acquiresome allowness due to geometry distortion of bothcomplexes
314 ESR Spectra For elucidation of the geometry of thecopper ternary complex ESR measurement gives veryuseful information about the stereo chemistry bondingbetween copper and ligands Figure 1S shows the ESRspectrum of the copper complex with a comparativeadvantage and axial symmetry (g || (parallel) 210748g (perpendicular) 201232 (204984) (ese valuesconfirm square planar coordination in which g || gt g gt 2so the unpaired electron found in the dx2 minus y2 orbital andthe ground state is 2B1g [38] (e observed and calculated
g values are different from ge 20023 due to spin-orbitcoupling (e computed g components are not equalreflecting anisotropic effect and the value of g changes as afunction of the orientation of the molecule relative to theexternal magnetic field (is value is close to the spin onlyvalue and it is in a fair agreement with the computed electronspin only value of ge(computed) 20498 [38] Co(II) com-plex is characterized by g 21280 (e simulated EPRspectrum of Co(II) complex returns ge value of 21085
Different values of Mulliken spin density are shown inFigure 4S in such metal-chelates point to purely anisotropiccouplings (e unpaired electron is totally localized onCo(II) ion In case of Cu(II)-complex electron spin pop-ulation is more distributed with about 46 on the Cu(II)ion(is may result in the simulated significant HF couplingin the case of chelating atoms around Cu(II) ion (e datapoint to mixed copper-nitrogen and copper-oxygen bondsin agreement with the computed optimized geometry [38]
32 +ermal Analysis (ermogravimetric analysis (TGA)for the all prepared ternary metal complexes was carried outin nitrogen atmosphere (e thermal decomposition of thefour complexes displayed similar patterns as their ligands
It is well known that amino acids exist only in solid stateso their thermal decomposition has been endothermal be-tween minus72 and minus151 kJmol when heating in range between185degC and 280degC (eir thermal decomposition releasesthree gases mainly H2O less NH3 and hardly any CO2TGA gives the weight of these gases as weight loss calcu-lations which evolve in appreciable amount [39]
Also the thermal decomposition of L-arginine-dopedKDP potassium dihydrogen phosphate crystal started to loseweight with temperature from 341K to 393K releasedammonia and water molecules gases [40]
(e amino acids are totally broken within the range603ndash793K as shown in Figure 6 and Table 5 (e first stepsare weight loss of the three gases H2O NH3 and CO2 withintemperature range about sim423ndash623K (e hydrocarbonsmatter loses weight in the temperature range sim350ndash520degC(e residues for these complexes are mixture with differentratios of metal and metal oxide above temperature range643ndash793K
It is noteworthy to mention that the geometries of thestudied complexes are similar to L-arginine metal complexreported before [41] which have been confirmed by X-raycrystallographic data of single crystals
33 Nanosized Metal Oxides Characterization
331 XRD of Nano CuO and Nano Cobaltosic Oxide(Co3O4) XRD of thermal synthesized copper oxide nano-particles starting from copper glutamic arginine-mixed li-gands complex gives characteristic peaks at 2θ 326deg 356deg387deg 489deg 536deg 582deg 616deg 663deg and 681deg for the markedindices of (110) (002) (111) (202) (020) (202) (113) (022)and (113) respectively as shown in Figure 7(a) which iscomparable with the literature values (e average primaryparticle size of the copper(II) oxide nanoparticles was
8 Journal of Chemistry
TG (m
g)
80
60
40
20
DTG
(mgmiddot
min
ndash1)
000
ndash020
ndash040
ndash060
ndash080
Weight loss ndash1925mgndash24174
Weight loss ndash1745mgndash21914
Weight loss ndash1366mgndash17154
Weight loss ndash0710mgndash8916
Weight loss ndash0276mgndash3466
273 473 673 873 1073 1273Temperature (K)
(a)
273 473 673 873 1073 1273Temperature (K)
TG (m
g)
100
50
DTG
(mgmiddot
min
ndash1)
000
ndash020
ndash040
ndash060
Weight loss ndash1890mgndash14111 Weight loss ndash8641mg
ndash64514
(b)
Figure 6 Continued
Alpha HOMO Alpha LUMO
Beta HOMO Beta LUMO
(a)
Alpha HOMO Alpha LUMO
Beta HOMO Beta LUMO
(b)
Figure 5 Frontier MOs of (a) Co(II) complex and (b) Cu(II) complex involved in the longest wavelength electronic transition Surfacessimilar to that of Co complex are obtained in case of Ni (ere are no d-d transitions in Zn complexes
Journal of Chemistry 9
Table 5 (ermogravimetric analysis decomposition data for the metal ternary complexes
Complexes Mol (wt) TG range (degC) Mass loss () found (calculated) Total mass loss () Assignment
Figure 6 TG and DTG of (a) [Co(glu)(arg)(H2O)2]middot05H2O (b) [Ni(glu)(arg)(H2O)2]middot05H2O (c) [Cu(glu)((arg)]middotH2O and(d) [ZnmiddotGlumiddotArgmiddot(H2O)2]middotH2O
10 Journal of Chemistry
estimated using well-known DebyendashScherrer formula usingthe full width at half maximum (FWHM) of the (111) peaksin the XRD K(α) is the wavelength of X-ray source(15406 A 015406 nm) β∆θ is the full width at halfmaximum (FWHM 01378) and θ 387 is the diffractionangle corresponding to the lattice plane (111) which gives Dsim143ndash204plusmn 08 nm patterns [42ndash44]
(e pattern of XRD for cobalt oxide nanoparticles showscharacteristic peaks at 2θ values at 1898deg 3127deg 3682deg3848deg 4478deg 5568deg 5934deg 6521deg and 7731deg which arecorresponding to their indices (111) (220) (311) (400) (511)and (440) in agreement with JCPDS Card No 76ndash1802 (ispattern confirms the phase formation of cobalt oxidenanoparticle Figure 7(b) (e average size of the Co3O4particles was calculated by the DebyendashScherrer equationDK(α) λ(β cos θ) whereD is the average crystalline size λ isthe wavelength of CuKα θ is Braggrsquos angle and β is the fullwidth at half maximum (FWHM) of the diffraction peak (eaverage dimension D is sim147ndash182plusmn 06 nm at 2θ 3682degwhich is the intense peak [44]
332 EDX of Nano CuO (e synthesized nano copperoxide is confirmed by the EDX spectrum and SEM imagemeasurement shown in Figure 8 which confirms the highestformation percent of CuO and traces of copper carbide (eSEM image for nano copper oxide CuO shows a mixingnanosize 270sim1079 nm [42 43]
333 EDX of Nano Cobaltosic Oxide (e synthesized nanocobalt oxide is confirmed by the EDX spectrum measure-ment shown in Figure 9 which confirms the highest for-mation percent of cobaltosic oxide Co3O4 and traces ofcobalt carbide (e SEM image for nano cobaltosic oxideCo3O4 shows a mixing nanosize 318ndash8543 nm
34 Applications
341 Biological Activity Mixed ligand ternary complexeshave been examined for their in vitro antimicrobial activity(is investigation was performed using the diffusion agartechnique (Figure 5S) (e assays collection included
g-negative (Pseudomonas aeruginosa RCMB 010043 andEscherichia coli RCMB 010052) pathogenic bacteria usingGentamicin 5mgml as a reference compound and g-pos-itive (Streptococcus pneumoniae RCMB 010010 and Bacillissubtilis RCMB 010067) pathogenic bacteria using Ampi-cillin 5mgml as a reference compound It was also in-cluded four fungi (Aspergillus fumigatus RCMB 02568Syncephalastrum racemosum RCMB 05922 Geotrichumcandidum RCMB 05097 and Candida albicans RCMB05036) using Amphotericin B 5mgml as a referencecompound [30 45]
(e inhibitory effects of the used ligands and theirternary polymer complexes against the used organisms aregiven in Table 6 In general the used ligands did not displayantifungal or antibacterial inhibitory
For antifungal assay examination and based on theminimum inhibitory concentration (MIC) values it is foundthat the inhibitory effect of all the ternary complexes varyfrom moderate to weak against Amphotericin B controlexcept in the case of Candida albicans (RCMB 05036) whichis not affected by both cobalt and zinc complexes
(e antibacterial activities of the obtained ternarycomplexes are determined in terms of MIC values As shownin Table 6 all complexes display moderate activities againstStreptococcus pneumonia (RCMB 010010) and Bacillis sub-tilis RCMB 010067 (e growth of the gram-negative bac-teria Pseudomonas aeruginosa RCMB 010043 andEscherichia coli RCMB 010052 is extremely affected by bothcopper and nickel complexes which display strong inhibitionagainst the gram-negative pathogenic bacteria with MICvalue less than the Gentamicin control (e remainingcomplexes do not display the same behavior during theassay
342 Cytotoxicity One of the fundamental goals in me-dicinal chemistry is the development of new anticancer andantimicrobial therapeutic agents Cancer treatment usingmetal-based drugs is one of the very effective strategies as themetal ions are capable of binding to nucleic acids stereo-specifically with varying strength
In vitro anticancer activity evaluation of the newlysynthesized compounds was carried out against human
Cou
nts
400
300
200
100
010 20 30 40
Angles (deg2θ)50 60 70
(a)
Cou
nts
100
50
010 20 30 40
Angles (deg2θ)50 60 70
(b)
Figure 7 XRD pattern of (a) copper oxide CuO and (b) cobalt oxide Co3O4 prepared by thermal decomposition at 550Cdeg starting frommetal glutamic arginine mixed ligands complex
Journal of Chemistry 11
cancer cell lines hepatocellular carcinoma (HePG2) becauseliver cancer is the third most common cause of death incancer using MTT method [26 46 47]
Doxorubicin HCl is one of the most effective anti-cancer agents is used as a reference drug in this study (eobtained results from Table 2S indicated that most of thesemoleculesrsquo behavior can be observed from the values of the
half maximal inhibitory concentration IC50 whichfor glutamic and arginine are 167 and 376 μgmlrespectively
IC50 results indicate that the ternary complexes havepromised inhibition of HePG2 liver tumors [48 49]
Cell viability was assessed by themitochondrial-dependentreduction of yellow MTT (3-(45-dimethylthiazol-2-yl)-25-
108K096K084K072K060K048K036K024K012K000K
000 100 200 300 400 500 600 700 800 900
Cu Kβ
Cu Kα
Cu L
O KC K
(a) (b)
Figure 8 EDX and SEM images of CuO obtained by thermal decomposition at 550Cdeg starting from copper glutamic arginine mixed ligandscomplex
135K120K105K090K075K060K045K030K015K000K
000 100 200 300 400 500 600 700 800 900
O K
Co L Co Kα
Co Kβ
(a) (b)
Figure 9 EDX and SEM images of Co3O4 obtained by thermal decomposition at 550Cdeg starting from cobalt glutamic arginine mixedligands complex
Table 6 Antimicrobial activity of prepared ternary metal complexes
Sample tested microorganisms Glutamicacid L-arginine (1) (2) (3) (4) Standard
lowastNA no activity Values in bracket are the MIC values
12 Journal of Chemistry
diphenyl tetrazolium bromide) to insoluble purple formazan[45] (e prepared ternary metal complexes are of differentviability percentages as depicted in Figure 10 Data of bothligands are also included for comparison
Table 2S shows that the ligands have lower inhibition ofHePG2 than their metal ternary complexes (e coppercomplex introduces the highest inhibition
Additionally Table 7 summarizes some computedelectrical reactivity [50] and thermodynamic propertiesfor Co(II) and Cu(II) complexes (as maximum andminimum IC50 of the four prepared ternary metalscomplexes) which are correlated with the inhibition ofhuman cancer cells and are useful to explain the roleplayed by molecular properties in inhibition of humancancer cells
(e simulated data summarized in Table 7 conclude thefollowing
(i) Cu complex is more energetically stable relative toCo complex by about minus265 kJmol
(ii) Cu complex is characterized by lower dipole mo-ment and lower polarizability relative to Co(II)complexes
(iii) Enthalpy and Gibbs free energy of the Cu complexesare more stable by about minus265 kJmol relative toCo(II) complex Lower entropy reflects lower degreeof randomness of Cu(II) complex
(iv) (e chemical potential (μprime) (negative of molecularelectronegativity) of Cu(II) complex is much higherthan that of Co(II) complex reflecting the enhancedreactivity of Cu(II) complex as nucleophile becauseμprime measures the escaping tendency of electrons fromthe complex (μprime (LUMO+HOMO)2) [50]
(v) Cu complex is characterized by lower hardness thanCo(II) complex Hardness measures the resistanceto electron transfer (η (LUMO-HOMO)2) [50]
It seems that more thermodynamically stable and lesspolar Cu complex exhibits that enhanced responsive elec-tron cloud transfer to the surrounding tumor relative to theCo(II) complex (ese quantitative molecular descriptors[50] explain the promising inhibition activity of the Cu(II)complex (e results are correlated with the above-discussedPES results which show that Cu complex could act asnucleophile whereas Co complex is of enhanced electro-philic nature
(e nucleophilicity of Cu complex (seeking for positivelycharged sites of the reactant) together with its electricalthermodynamic and molecular properties favors its prom-ising inhibition activity towards HePG2 cancer cell [51ndash53]
343 Corrosion Inhibition of Aluminum An assessment ofcorrosion rates and inhibition efficiency for aluminum withdifferent inhibitor concentrations were computed as followscorrosion rate Rcorr was computed using equation (5)
Rcorr M1 minusM2( 1113857(mg)
A cm2( ) times t(h) (5)
where M1 weight (g) before immersion M2 weight (g)after immersion A area (cm2) of the specimen andt exposure time (h)
(e inhibition efficiency (IE) was evaluated usingequation (6)
IE Rblank minusRinh
Rblank1113890 1113891 times 100 (6)
120
60
100
80
60
40
20
00 10 20 30 40 50
GlutamicLarginineCu(II)
Ni(II)Co(II)Zn(II)
Figure 10 Cell viability of (HePG2) at different concentrations of ligands and the prepared metal complexes
Table 7 Simulated electrical properties of complexes studied exhibiting enhanced inhibition of HePG2
where Rblank corrosion rates in the absence of inhibitor andRinh corrosion rates in the presence of inhibitor [16]
Table 8 shows the calculated corrosion rates and inhibitionefficiencies of aluminum specimens in aqueous solution of 1MHCl as the corrosive medium in absence and presence ofmixed ligands and their ternary metal complexes at differenttemperatures (293 ndash313) K for 7 hours of each concentrationFigure 6S shows that as the concentration of ligands and theircomplexes increases Rcorr decreases and IE increases formixed ligands and their metal complexes acted as more ef-ficient inhibitors than their mixed ligands alone
344 Adsorption Isotherms and the +ermodynamic Acti-vation Parameters (e metal surface coverage degree(θIE100) was subjected to different adsorption iso-therms (e well fit for weight loss data is obtained forLangmuir adsorption isotherm Figure 11
Table 8 Corrosion parameters for aluminum in aqueous solution of 1M HCl in the absence and presence of different concentrations ofmixed ligands and their metal complexes at different temperatures for 7 hrs
Inhibitors C (times10minus2M)Corrosion rate times10minus4
Figure 11 Langmuir adsorption isotherms of the mixed ligands(L) and their metal complexes
14 Journal of Chemistry
(e temperature effect (293ndash313 K) on aluminum weightloss inhibition may be attributed to two main mechanismsphysical and chemical adsorption [37] (e suggested mech-anisms are obtained as the temperature increases the efficiencydecreases for mixed ligands but increases for their metalcomplexes depending on the nature of bond formation be-tween the mixed ligands and aluminum surface which isdifferent from the nature of bond formation between metalcomplexes and the aluminum surface [16] Arrhenius equation(7) gives the relation between the corrosion rate andtemperature
lnRcorr lnAminusElowast
RT (7)
where A is the Arrhenius factor Elowast is the apparent activationenergy of the corrosion process R is the rate gas constant andT is the absolute temperature (e straight line slope oflogRcorr vs 1T for aluminum 1M HCl at 4times10minus4molL after7 h is minusElowast2303R for the inhibitors (Figure 12)
(e activation thermodynamic parameters for alumi-num dissolution could be obtained from the transition stateequation (8)
lnRcorr
T1113874 1113875 ln
R
Nh1113874 1113875 +
ΔSlowast
R1113888 1113889minus
ΔHlowast
RT1113888 1113889 (8)
where the entropy of activation ∆Slowast and the apparent en-thalpy of activation ∆Hlowast can be obtained from the intercept
3150
02
04
06
logR
corr
(gmiddoth
ndash1middotcm
ndash1)
08
1
12
32 325 331000T(Kndash1)
335 34 345
BlankMix ligandsZn2+
Co2+Ni2+Cu2+
Figure 12 Arrhenius of log corrosion rate (Rcorr) vs 1T for aluminum in 1M HCl without and with 004times10minus2MLminus1 of inhibitors (mixedligands and their metal complexes)
Table 9 (ermodynamic parameters for the adsorption of (004times10minus2)ML mixed ligands and their metal complexes on aluminum metalin aqueous solution of 1M HCl at different temperatures for 7 hrs
and the slope for the straight line of the relation betweenln(RcorrT) vs (1T) respectively N is Avogadrorsquos numberand h is Planckrsquos constant (e Gibbs free energy of acti-vation ∆Glowast can be detected by equation (9)
ΔGlowast ΔHlowast minusTΔSlowast (9)
Table 9 shows the thermodynamic parameters for theadsorption of mixed ligands and their metal complexes (epositive value of ∆Hlowast indicated the endothermic property ofdissolution process nature for aluminum in the acidicmedium [54]
However the blank ΔHlowast value is higher than the in-hibitor metal complexes which indicated that the inhibitionefficiency generally increases with increasing temperature(e association step is the rate-determining step rather thana dissociation process in presence of the metal complexesinhibitors due to the negative values of ΔSlowast It is known thatthe values of ΔGlowast above 40 kJmiddotmolminus1 are referred to chargetransfer from the inhibitor molecules into aluminum surfaceto form coordinated compound on the Al surface whichblocks it against corrosion process by different degrees Alsothe chemical adsorption process mechanism is confirmed bythe values of ΔGlowast above 40 kJmiddotmolminus1 [16 54ndash56]
4 Conclusions
Novel coordination materials of ternary divalent metalions (Cu(II) Ni(II) Co(II) and Zn(II)) chelated by thebidentate glutamic acid (Glu) and L-arginine (Arg) aminoacids are synthesized and characterized (e metal ionscomplexes are modelled using density DFT and TD-DFTtheory Computed molecular and spectroscopic (IR UV-Vis and EPR) properties validated the experimental re-sults (e used computational methods are capable ofproviding good structural descriptions for the TM com-plexes Consistent with the experimental properties theoptimized structures of the complexes [Cu(II) Glu-Arg]and [Co(II) Glu-Arg (H2O)2] reveal that symmetry en-vironment of Cu(II) exhibits slightly distorted squareplanar shape whereas Co(II)-complex has a distortedoctahedral (where Co(II) central ion is of C4v-localsymmetry) Spectral properties of [Ni(II) Glu-Arg(H2O)2] and [ZnmiddotGlumiddotArgmiddot(H2O)2] complexes indicatethat they have similar structure as Co(II) complex All thestudied ternary metal complexes are of different anti-fungal activities ranging from moderate to weak withoutpractically noticed inhibitory effects whereas antibacte-rial activities of all studied metal complexes show sig-nificant effects
Cytotoxicity studies against (HePG2) reveal the prom-ising potentiality of Cu(II) complex as inhibitor of cancercells(e results are correlated with the computed moleculardescriptors including dipole moment polarizability ther-modynamics and reactivity properties as well as the PESmaps
(e corrosion inhibition of aluminum metal specimensin 1M HCl is efficiently achieved by mixed ligands and theirmetal complexes studied
Data Availability
(e data used to support the findings of this study areavailable from the corresponding author upon request
Conflicts of Interest
(e authors declare that they have no conflicts of interest
Supplementary Materials
(e supplementary materials consist of six figures and twotables to further clarify the structures and trends of the newlyprepared metal ternary complexes (SupplementaryMaterials)
References
[1] Z Ozturk D A Kose A Asan et al ldquoPorous metal-organicCu(II) complex of L-Arginine 2synthesis characterizationhydrogen storage properties and molecular simulation cal-culationsrdquo Hittite Journal of Science and Engineering vol 1no 1 pp 1ndash5 2014
[2] S A Lahsasni R A Ammar M F Amin et al ldquoMixed-ligandcomplex formation of Cu(II) with 12- diphenylethylenedi-amine as primary ligand and amino acids as secondary li-gandsrdquo International Journal of Electrochemical Sciencevol 7 pp 7699ndash7711 2012
[3] H Sigel B P Operschall S S Massoud B Song andR Griesser ldquoEvidence for intramolecular aromatic-ringstacking in the physiological pH range of the mono-deprotonated xanthine residue in mixed-ligand complexescontaining xanthosinate 5prime-monophosphate (XMP)rdquo DaltonTransactions vol 46 no 46 pp 5521ndash5529 2006
[4] S Udhayakumar K G Shankar S Sowndarya S VenkateshC Muralidharan and C Rose ldquol-Arginine intercedes bio-crosslinking of a collagen-chitosan 3D-hybrid scaffold fortissue engineering and regeneration in silico in vitro and invivo studiesrdquo RSC Advances vol 7 no 40 pp 25070ndash250882017
[5] P K Datta M Chandra and A K Dey ldquoTernary complexesof copper(II) nickel(II) and zinc(II) with nitrilotriacetic acidas a primary ligand and some phenolic acids as secondaryligandsrdquo Transition Metal Chemistry vol 5 no 1ndash3 1980
[6] J S Woertink L Tian D Maiti et al ldquoSpectroscopic andcomputational studies of an end-on bound superoxo-Cu(II)complex geometric and electronic factors that determine theground staterdquo Inorganic Chemistry vol 49 no 20pp 9450ndash9459 2010
[7] S Dutta S Ray K Nagarajan et al ldquoGlutamic acid analoguesused as potent anticancer a reviewrdquo Der Pharma Chemicavol 3 no 2 pp 263ndash272 2011
[8] T Sismanoglu S Pura and A Bastug ldquoBinary and ternarymetal complexes of Congo red with amino acidsrdquo Dyes andPigments vol 70 no 2 pp 136ndash142 2006
[9] R N Patel H C Pandey K B Pandeya et al ldquoMixed ligandcomplex formation of nickel(II)copper(II) and zinc(II) withsome amino acids and imidazolesrdquo Indian Journal ofChemistry-Section A Inorganic Physical +eoretical andAnalytical Chemistry vol 38 no 8 pp 850ndash853 1999
[10] L Meng and Z Lin ldquoComplexations of alkalialkaline earthmetal cations with gaseous glutamic acidrdquo Computational and+eoretical Chemistry vol 1039 pp 1ndash10 2014
16 Journal of Chemistry
[11] L D Pinto P A L Puppin V M Behring O C AlvesN A Rey and J Felcman ldquoSolution and solid state study ofcopper(II) ternary complexes containing amino acids of in-terest for brain biochemistry-2 homocysteine with aspartateglutamate or methioninerdquo Inorganica Chimica Acta vol 386pp 60ndash67 2012
[12] A Wojciechowska A Ggor and W Zierkiewicz ldquoChiraloctahedral complexes of Co(III) as catalysts for asymmetricepoxidation of chalcones under phase transfer conditionsrdquoRSC Advances vol 5 no 46 pp 36295ndash36306 2015
[13] B M Weckhuysen A A Verberckmoes L Fu andR A Schoonheydt ldquoZeolite-encapsulated copper(II) aminoacid complexes synthesis spectroscopy and catalysisrdquo Journalof Physical Chemistry vol 100 no 22 pp 9456ndash9461 1996
[14] K Y El-Baradie N A El-Wakiel and H A El-GhamryldquoSynthesis characterization and corrosion inhibition in acidmedium ofl-histidine Schiff base complexesrdquo Applied Or-ganometallic Chemistry vol 29 no 3 pp 117ndash125 2015
[15] S S R Anthony and R Susai ldquoInhibition of corrosion ofcarbon steel in well water by arginine-Zn2+ systemrdquo Journal ofElectrochemical Science and Engineering vol 2 no 2pp 91ndash104 2012
[16] E H Isamil F F AlBlewi N Soliman and M M H Khalilldquo(ermal studies and mass loss inhibition for some newmixed amino acid metal complexes with their applicationsrdquoJournal of +ermal Analysis and Calorimetry vol 125 no 1pp 289ndash300 2016
[17] F Neese ldquo(e ORCA program system 4012rdquo Wiley In-terdisciplinary Reviews Computational Molecular Sciencevol 2 no 1 pp 73ndash78 2012
[18] S Grimme S Ehrlich and L Goerigk ldquoEffect of the dampingfunction in dispersion corrected density functional theoryrdquoJournal of Computational Chemistry vol 32 no 7pp 1456ndash1465 2011
[19] S Grimme J Antony S Ehrlich and H Krieg ldquoA consistentand accurate ab initio parametrization of density functionaldispersion correction (DFT-D) for the 94 elements H-Purdquo+e Journal of Chemical Physics vol 132 no 15 article154104 2010
[20] F Weigend ldquoHartree-Fock exchange fitting basis sets for H toRnrdquo Journal of Computational Chemistry vol 29 no 2pp 167ndash175 2008
[21] F Neese F Wennmohs and A Hansen ldquoEfficient ap-proximate and parallel Hartree-Fock and hybrid DFT cal-culations A lsquochain-of-spheresrsquo algorithm for the Hartree-Fock exchangerdquo Chemical Physics vol 356 no 1ndash3pp 98ndash109 2009
[22] R Izsak and F Neese ldquoAn overlap fitted chain of spheresexchange methodrdquo Journal of Chemical Physics vol 135no 14 article 144105 2011
[23] T Petrenko S Kossmann and F Neese ldquoEfficient time-dependent density functional theory approximations forhybrid density functionals analytical gradients and paralle-lizationrdquo Journal of Chemical Physics vol 134 no 5 article054116 2011
[24] A V Marenich C J Cramer and D G Truhlar ldquoUniversalsolvation model based on solute electron density and on acontinuum model of the solvent defined by the bulk dielectricconstant and atomic surface tensionsrdquo Journal of PhysicalChemistry B vol 113 no 18 pp 6378ndash96 2009
[25] S Donovan C Stiefbold and K Sprague ldquoChapter 3Chemical properties of amino acids and identification ofunknown amino acidsrdquo in Proceedings of the 17 thWorkshopConference of the Association for Biology
Laboratory Education (ABLE) vol 17 pp 35ndash70 Bain-bridge GA USA March 1996
[26] C C Wagner J Enrique and C Claudia ldquoVibrational andmagnetic properties of a CuMg glutamate complexrdquoArgentina Acta Farm Bonaerense vol 22 no 2 pp 137ndash1422003
[27] M Arif R Sur and M Arshad ldquoStudies on the thermaldecomposition of copper (II) flouride complexes with variousamino acids in nitrogen atmosphererdquo Turkish Journal ofChemistry vol 25 pp 73ndash79 2001
[28] A Ghosh M J Tucker and R M Hochstrasser ldquoIdentifi-cation of arginine residues in peptides by 2d-IR echo spec-troscopyrdquo Journal of Physical Chemistry A vol 115 no 34pp 9731ndash9738 2011
[29] K Nakamoto Infrared Spectra of Inorganic and CoordinationCompounds Part B Wiley-Interscience New York NY USA5th edition 1997
[30] E Santi M H Torre E Kremer S B Etcheverry andE J Baran ldquoVibrational spectra of the copper(II) and nick-el(II) complexes of piroxicamrdquo Vibrational Spectroscopyvol 5 no 3 pp 285ndash293 1993
[31] H N Aliyu and A S Mohammed ldquoSynthesis spectropho-tometric and biological activity of nickel (II) and copper (II)complexes with schiff base derived from acetylacetone andhistidinerdquo Global Advanced Research Journal of Microbiologyvol 1 no 5 pp 67ndash71 2012
[32] J S Murray and P Politzer ldquo(e electrostatic potential anoverviewrdquo Wiley Interdisciplinary Reviews ComputationalMolecular Science vol 1 no 2 pp 153ndash163 2011
[33] E R Souaya M M H Khalil and E H Ismail ldquoSynthesis andcharacterization of ternary complexes of certain hydroxylacids and their biological applicationsrdquo Research Journal ofPharmaceutical Biological and Chemical Sciences vol 5 no 4pp 18ndash30 2014
[34] N N Greenwood and A Earnshaw A Review of Chemistry ofthe Elements Pergamon Press Oxford UK 1984
[35] V Reddy N Patil and S D Angadi ldquoSynthesis character-ization and antimicrobial activity of Cu(II) Co(II) and Ni(II)complexes with ON and S Donor ligandsrdquo E-Journal ofChemistry vol 5 no 3 pp 577ndash583 2008
[36] F A Cotton G Wilkinson C A Murillo et al Advances inSchiff Base Chemistry Wiley New York NY USA 6th edi-tion 1999
[37] M M H Khalil E H Ismail S A Azim and E R SouayaldquoSynthesis characterization and thermal analysis of ternarycomplexes of nitrilotriacetic acid and alanine or phenylala-nine with some transition metalsrdquo Journal of +ermalAnalysis and Calorimetry vol 101 no 1 pp 129ndash135 2010
[38] F Mabbs and D Colisson Electron Paramagnetic Resonanceof D Transition Metal Compounds Vol 102 ElsevierAmsterdam Netherlands 1992
[39] M M H Khalil E R Souaya E H Ismail et al ldquoTernarytransition metal complexes of nitrilotriacetic acid and valineor leucine synthesis and biological applicationsrdquo ChineseJournal of Inorganic Chemistry vol 29 no 9 pp 1969ndash19782013
[40] I M Weiss C Muth R Drumm and H O K Kirchnerldquo(ermal decomposition of the amino acids glycine cysteineaspartic acid asparagine glutamic acid glutamine arginineand histidinerdquo BMC Biophysics vol 11 no 1 2018
[41] A M Petrosyan V V Ghazaryan G Giester and M FleckldquoSulfamates and methanesulfonates of L-arginine and L-his-tidinerdquo Journal of Molecular Structure vol 1163 pp 114ndash1272018
Journal of Chemistry 17
[42] T Kavitha S Haider T Kamal and M Ul-Islam ldquo(ermaldecomposition of metal complex precursor as route to thesynthesis of Co3O4 nanoparticles antibacterial activity andmechanismrdquo Journal of Alloys and Compounds vol 704pp 296ndash302 2017
[43] E M M Ibrahim L H Abdel-Rahman A M Abu-DiefA Elshafaie S K Hamdan and A M Ahmed ldquo(e synthesisof CuO andNiO nanoparticles by facile thermal decompositionof metal-Schiff base complexes and an examination of theirelectric thermoelectric and magnetic Propertiesrdquo MaterialsResearch Bulletin vol 107 pp 492ndash497 2018
[44] S Farhadi M Javanmard and G Nadri ldquoCharacterization ofcobalt oxide nanoparticles prepared by the thermal de-compositionrdquo Acta Chimica Slovenica vol 63 pp 335ndash3432016
[45] E M Zayed E H Ismail G G Mohamed M M H Khaliland A B Kamel ldquoSynthesis spectroscopic and structuralcharacterization and antimicrobial studies of metal com-plexes of a new hexadentate Schiff base ligand Spectropho-tometric determination of Fe(III) in water samples using arecovery testrdquo Monatshefte fur Chemie-Chemical Monthlyvol 145 no 5 pp 755ndash765 2014
[46] V Milacic D Chen L Ronconi K R Landis-PiwowarD Fregona and Q P Dou ldquoA novel anticancer gold(III)dithiocarbamate compound inhibits the activity of a purified20S proteasome and 26S proteasome in human breast cancercell cultures and xenograftsrdquo Cancer Research vol 66 no 21pp 10478ndash10486 2006
[47] T Mosmann ldquoRapid colorimetric assay for cellular growthand survival application to proliferation and cytotoxicityassaysrdquo Journal of Immunological Methods vol 65 no 1-2pp 55ndash63 1983
[48] R L Siegel K D Miller and A Jemal ldquoCancer statistics2018rdquo CA A Cancer Journal for Clinicians vol 68 no 1pp 7ndash30 2018
[49] S Chattopadhyay S P Chakraborty D Laha et al ldquoSurface-modified cobalt oxide nanoparticles new opportunities foranti-cancer drug developmentrdquo Cancer Nanotechnol vol 3no 1-6 pp 13ndash23 2012
[50] F Zielinski V Tognetti and L Joubert ldquoCondensed de-scriptors for reactivity a methodological studyrdquo ChemicalPhysics Letters vol 527 pp 67ndash72 2012
[51] H Wang Y He Q Yan et al ldquoCorrelation between thedielectric properties and biological activities of human ex vivohepatic tissuerdquo Physics in Medicine and Biology vol 60 no 6pp 2603ndash2617 2015
[52] F Tao F Fu F You et al ldquo(e correlation between dielectricproperties and microstructure of femoral bone in rats withdifferent bone qualitiesrdquo Annals of Biomedical Engineeringvol 42 no 6 pp 1238ndash1249 2014
[53] L Gun D Ning and Z Liang ldquoEffective permittivity ofbiological tissue comparison of theoretical model and ex-perimentrdquo Mathematical Problems in Engineering vol 2017Article ID 7249672 2017
[54] E I Ating S A Umoren I I Udousoro E E Ebenso andA P Udoh ldquoLeaves extract of Ananas sativumas greencorrosion inhibitor for aluminium in hydrochloric acid so-lutionsrdquo Green Chemistry Letters and Reviews vol 3 no 2pp 61ndash68 2010
[55] E Hamed ldquoStudies of the corrosion inhibition of copper inNa2SO4 solution using polarization and electrochemicalimpedance spectroscopyrdquo Materials Chemistry and Physicsvol 121 no 1-2 pp 70ndash76 2010
[56] H Zarrok H Oudda A Zarrouk et al ldquoWeight loss mea-surement and theoretical study of new pyridazine compoundas corrosion inhibitor for C38 steel in hydrochloric acidsolutionrdquo Der Pharma Chemica vol 3 no 6 pp 576ndash5902011
18 Journal of Chemistry
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Bioinorganic Chemistry and ApplicationsHindawiwwwhindawicom Volume 2018
SpectroscopyAnalytical ChemistryInternational Journal of
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Hindawiwwwhindawicom Volume 2018
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nom
ate
ria
ls
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Journal ofNanomaterials
Submit your manuscripts atwwwhindawicom
(e C-NH2 stretching bands of the guanidyl group ofalpha amino group have shifted from 1242 to 1175 cmminus1 ofglutamic acid and L-arginine with respect into (1122ndash1131)cmminus1 of the prepared metal complexes In opposite situationarginine has been shown to have two bands observed at 1586and 1608 cmminus1 due to the asymmetrical vibrations of theC-NH2 bonds of the guanidino group which is protonatedto give the guanidinium form without a significant change incase of complexation [28]
(e asymmetrical (υCOOasy) and symmetrical(υCOOsy) carboxylic groups are shifted in the preparedcomplexes to higher or lower values than their values inligands case as shown in Tables 2 and 3 and also thedifference between these bands are more than 200 cmminus1 inall the prepared metal complexes which indicated that thedeprotonated carboxylic groups in both ligands act asmono dentate groups
All the prepared complexes exhibited bands in the rangeof 3340ndash3472 cmminus1 of υ(OH) signifying that H2O moleculesexist in these complexes [29 30]
(e new confirmed bands only appear in the fourprepared complexes at 538ndash572 cmminus1 and 412ndash456 cmminus1which are assigned to υ(M-O) and υ(M-N) stretching bandsrespectively [31]
(e optimized geometry of the complexes shows dis-torted overall octahedral (or better the square pyramidalC4v-local symmetry of Co(II) ion) for the Co(II) complexand the slightly distorted square planar coordination of theCu(II) ion in the Cu(II) complex Ni and Zn complexes areof similar geometry to the Co complexes Figure 3 shows thatthe local symmetry of both centrosymmetric cations isnoticeably distorted with different M(II)-O and M(II)-Nbond lengths and bond angles indicated in Figure 2
(e simulated PES maps [32] which shed light on thebinding sites of the complexes are depicted in Figure 3Inspection of Figure 3 shows that Co(II) complex exhibits
larger positive potentials (299 kJmol) than Cu(II) complexwhich bears enhanced negative potential than that on Co(II)complex (the difference between negative and positive po-tential energy limits (Delta) PES 24 and minus9 kJmol forCo(II) and Cu(II) complexes respectively) (us Cu(II)complex could act as nucleophile whereas Co(II) complex isof enhanced electrophilic nature during interactions
312 Mass Spectra (e mass spectra of the four complexeswere recorded and provided good evidence and confirma-tion of the molecular weight of these complexes (molecularion peaks (MIPs) are detected under severe experimentalconditions [16] which results in of splitting of crystallinewater) (Figure 2S shows the mass spectrum of Zn(II)complex as example)
313 UV-Vis Absorption Spectra Figure 4 shows the the-oretical and experimental UV-Vis spectra of Co(II) andCu(II) as examples (e results confirm that 1 2 and 4complexes have almost tetragonal distorted octahedralstructure (C4v-local symmetry) with different distortiondegrees which is obvious from the wavenumber and 10Dqvalues of the complexes compared to their literature values[33] Cu complex exhibits slightly distorted square planarshape Table 4 shows electronic spectral data and ligand fieldparameters such asDq B (free ion) B (complex) and β usingband-fitting equation [34 35]
(e value of Racah parameter B (free ion) is larger thanthat of B (complex) due to the covalence bonding of thecomplex (e value of β (nephelauxetic ratio)lt 1 is calcu-lated according to equation (1) βlt 1 validating octahedralgeometry [34 35]
β B(free ion)
B(complex) (1)
Table 3 Experimentally and theoretically simulated IR spectra (in cmminus1) of the studied complexes Assignment of theoretically calculated IRkey modes for Co(II) and Cu(II) complexes in the gas phase Excellent match between experimentally determined and theoreticallycomputed IR modes in case of Ni and Zn complexes is obtained
Complex υ (OH) υ (COO) υ (M-O) υ (M-N)
[Co(glu)(arg)(H2O)2]middotH2O2513 (H-bonded H2O and O of COO of Gu) 16848 (Ar) 5543 46363521 1740 (Gu)
Spectral data and assignments are summarized inTable 4
10Dq for the nickel complex was determined by twoprocedures [34]
(e first one is by solving equations (2) and (3) using theenergy terms of the different triplet states transitions sup-plied for Ni(II) [34] as shown in Table 4
(en applying the trial and error procedure a value for∆ that fits in equations (2) and (3) was found to be10935 cmminus1 which suggested the octahedral structure (esecond method for calculating 10Dq used Tanabe andSugano diagrams for the different metal ion complexesFrom Ni(II) diagram we could be able to deduce the ex-pected positions of the (3A2g⟶ 3T2g) and the(3A2g⟶ 3T1g) transitions (is method corresponds to a
pure crystal field approach and assumes that the value ofthe free ion Racah parameter (B) is maintained in thecomplex
Applying this procedure and considering the ratio of ]1]2 1582225641 062 the best vertical line which fulfilsthis ratio cuts the ∆B axis at a value of 139 and Bcomplexis calculated by equation (4) We found the value765273 cmminus1
299
ndash275
299
ndash275
(a)
272
ndash272
272
ndash272
(b)
Figure 3 PES maps (a) Co complex (upper pan solid surfaces and lower pan clipped surfaces) and legend color codes given in kJmol(b) Cu complex (upper pan solid surfaces and lower pan clipped surfaces)
(4) mdash mdash 221 ]1 45249 Charge transfer mdash mdash
Tetragonal distortionpseudosquarepyramidal
(distorted octahedral)
Journal of Chemistry 7
Bcomplex 2v21 + v22 minus 3v1v2( 1113857
15v2 minus 27v1( 1113857 (4)
(en 10Dq 10637253 cmminus1 is compared to the value of10935 cmminus1 obtained by the first method and both valuesconfirm octahedral structure [34] (e magnetic moment ofthe nickel complex was 31 which also confirmed octahedralstructure [16]
Racah parameters for Co(II) complex is also calculatedsimilarly
Furthermore Co(II) complexes have the effectivemagnetic moment μeff 413 (is value is higher than spinonly moment for three unpaired electrons 389 due to aconsiderable orbital contribution [34 36]
(e Zn complex did not show any d-d transitions butdisplayed charge transfer bands as shown in Table 4 (eexistence of charge transfer was due to transition betweentwo different principle quantum numbers from three to fouras distorted tetrahedron being completed by two watermolecules and forms zinc octahedral complex [34ndash37]
(e longest wavelength weak peaks are observed at516 nm (ε middotM 206 Lmiddotmolminus1middotcmminus1) and 636 nm (ε middotM
179 Lmiddotmolminus1middot cmminus1) for Co(II) and Cu(II) complexes re-spectively (e use of TD-DFT at BP86 DEF2-SVP andauxiliary basis DEF2JK level in water (using SMD solvationmodel) [24] results in λmax Co 5291 nm (oscillatorstrength f 0003) and λmax Cu 6486 nm (f 00256)which are in excellent agreement with the experimentalresults
(e computed natural transition orbitals of the longestwavelength transitions in both complexes reveal the largest(greater than 82) contribution of beta HOMO-LUMOwith minor (about 108) contribution of alpha HOMO-LUMO in case of Co(II) complex and about 992 con-tribution from the beta-HOMO-LUMO in case of Cu(II)complex MOs involved in the electronic transitions aredepicted in Figure 5 which illustrate clear dxz or dyz(e)⟶ dz2 (a1) transition in the local square pyramidal(C4v) of Co(II) ion in the Co(II) complex Metaldxy(b2g)minus dx2 minusy2(b1g) transition is dominant in case oflocal square planar symmetry of the Cu(II) complex (is isapproved by low molar absorptivity experimentally ob-served in the UV-Vis spectra of both complexes andsupported by low value of the computed oscillatorstrengths of the forbidden d-d transitions which acquiresome allowness due to geometry distortion of bothcomplexes
314 ESR Spectra For elucidation of the geometry of thecopper ternary complex ESR measurement gives veryuseful information about the stereo chemistry bondingbetween copper and ligands Figure 1S shows the ESRspectrum of the copper complex with a comparativeadvantage and axial symmetry (g || (parallel) 210748g (perpendicular) 201232 (204984) (ese valuesconfirm square planar coordination in which g || gt g gt 2so the unpaired electron found in the dx2 minus y2 orbital andthe ground state is 2B1g [38] (e observed and calculated
g values are different from ge 20023 due to spin-orbitcoupling (e computed g components are not equalreflecting anisotropic effect and the value of g changes as afunction of the orientation of the molecule relative to theexternal magnetic field (is value is close to the spin onlyvalue and it is in a fair agreement with the computed electronspin only value of ge(computed) 20498 [38] Co(II) com-plex is characterized by g 21280 (e simulated EPRspectrum of Co(II) complex returns ge value of 21085
Different values of Mulliken spin density are shown inFigure 4S in such metal-chelates point to purely anisotropiccouplings (e unpaired electron is totally localized onCo(II) ion In case of Cu(II)-complex electron spin pop-ulation is more distributed with about 46 on the Cu(II)ion(is may result in the simulated significant HF couplingin the case of chelating atoms around Cu(II) ion (e datapoint to mixed copper-nitrogen and copper-oxygen bondsin agreement with the computed optimized geometry [38]
32 +ermal Analysis (ermogravimetric analysis (TGA)for the all prepared ternary metal complexes was carried outin nitrogen atmosphere (e thermal decomposition of thefour complexes displayed similar patterns as their ligands
It is well known that amino acids exist only in solid stateso their thermal decomposition has been endothermal be-tween minus72 and minus151 kJmol when heating in range between185degC and 280degC (eir thermal decomposition releasesthree gases mainly H2O less NH3 and hardly any CO2TGA gives the weight of these gases as weight loss calcu-lations which evolve in appreciable amount [39]
Also the thermal decomposition of L-arginine-dopedKDP potassium dihydrogen phosphate crystal started to loseweight with temperature from 341K to 393K releasedammonia and water molecules gases [40]
(e amino acids are totally broken within the range603ndash793K as shown in Figure 6 and Table 5 (e first stepsare weight loss of the three gases H2O NH3 and CO2 withintemperature range about sim423ndash623K (e hydrocarbonsmatter loses weight in the temperature range sim350ndash520degC(e residues for these complexes are mixture with differentratios of metal and metal oxide above temperature range643ndash793K
It is noteworthy to mention that the geometries of thestudied complexes are similar to L-arginine metal complexreported before [41] which have been confirmed by X-raycrystallographic data of single crystals
33 Nanosized Metal Oxides Characterization
331 XRD of Nano CuO and Nano Cobaltosic Oxide(Co3O4) XRD of thermal synthesized copper oxide nano-particles starting from copper glutamic arginine-mixed li-gands complex gives characteristic peaks at 2θ 326deg 356deg387deg 489deg 536deg 582deg 616deg 663deg and 681deg for the markedindices of (110) (002) (111) (202) (020) (202) (113) (022)and (113) respectively as shown in Figure 7(a) which iscomparable with the literature values (e average primaryparticle size of the copper(II) oxide nanoparticles was
8 Journal of Chemistry
TG (m
g)
80
60
40
20
DTG
(mgmiddot
min
ndash1)
000
ndash020
ndash040
ndash060
ndash080
Weight loss ndash1925mgndash24174
Weight loss ndash1745mgndash21914
Weight loss ndash1366mgndash17154
Weight loss ndash0710mgndash8916
Weight loss ndash0276mgndash3466
273 473 673 873 1073 1273Temperature (K)
(a)
273 473 673 873 1073 1273Temperature (K)
TG (m
g)
100
50
DTG
(mgmiddot
min
ndash1)
000
ndash020
ndash040
ndash060
Weight loss ndash1890mgndash14111 Weight loss ndash8641mg
ndash64514
(b)
Figure 6 Continued
Alpha HOMO Alpha LUMO
Beta HOMO Beta LUMO
(a)
Alpha HOMO Alpha LUMO
Beta HOMO Beta LUMO
(b)
Figure 5 Frontier MOs of (a) Co(II) complex and (b) Cu(II) complex involved in the longest wavelength electronic transition Surfacessimilar to that of Co complex are obtained in case of Ni (ere are no d-d transitions in Zn complexes
Journal of Chemistry 9
Table 5 (ermogravimetric analysis decomposition data for the metal ternary complexes
Complexes Mol (wt) TG range (degC) Mass loss () found (calculated) Total mass loss () Assignment
Figure 6 TG and DTG of (a) [Co(glu)(arg)(H2O)2]middot05H2O (b) [Ni(glu)(arg)(H2O)2]middot05H2O (c) [Cu(glu)((arg)]middotH2O and(d) [ZnmiddotGlumiddotArgmiddot(H2O)2]middotH2O
10 Journal of Chemistry
estimated using well-known DebyendashScherrer formula usingthe full width at half maximum (FWHM) of the (111) peaksin the XRD K(α) is the wavelength of X-ray source(15406 A 015406 nm) β∆θ is the full width at halfmaximum (FWHM 01378) and θ 387 is the diffractionangle corresponding to the lattice plane (111) which gives Dsim143ndash204plusmn 08 nm patterns [42ndash44]
(e pattern of XRD for cobalt oxide nanoparticles showscharacteristic peaks at 2θ values at 1898deg 3127deg 3682deg3848deg 4478deg 5568deg 5934deg 6521deg and 7731deg which arecorresponding to their indices (111) (220) (311) (400) (511)and (440) in agreement with JCPDS Card No 76ndash1802 (ispattern confirms the phase formation of cobalt oxidenanoparticle Figure 7(b) (e average size of the Co3O4particles was calculated by the DebyendashScherrer equationDK(α) λ(β cos θ) whereD is the average crystalline size λ isthe wavelength of CuKα θ is Braggrsquos angle and β is the fullwidth at half maximum (FWHM) of the diffraction peak (eaverage dimension D is sim147ndash182plusmn 06 nm at 2θ 3682degwhich is the intense peak [44]
332 EDX of Nano CuO (e synthesized nano copperoxide is confirmed by the EDX spectrum and SEM imagemeasurement shown in Figure 8 which confirms the highestformation percent of CuO and traces of copper carbide (eSEM image for nano copper oxide CuO shows a mixingnanosize 270sim1079 nm [42 43]
333 EDX of Nano Cobaltosic Oxide (e synthesized nanocobalt oxide is confirmed by the EDX spectrum measure-ment shown in Figure 9 which confirms the highest for-mation percent of cobaltosic oxide Co3O4 and traces ofcobalt carbide (e SEM image for nano cobaltosic oxideCo3O4 shows a mixing nanosize 318ndash8543 nm
34 Applications
341 Biological Activity Mixed ligand ternary complexeshave been examined for their in vitro antimicrobial activity(is investigation was performed using the diffusion agartechnique (Figure 5S) (e assays collection included
g-negative (Pseudomonas aeruginosa RCMB 010043 andEscherichia coli RCMB 010052) pathogenic bacteria usingGentamicin 5mgml as a reference compound and g-pos-itive (Streptococcus pneumoniae RCMB 010010 and Bacillissubtilis RCMB 010067) pathogenic bacteria using Ampi-cillin 5mgml as a reference compound It was also in-cluded four fungi (Aspergillus fumigatus RCMB 02568Syncephalastrum racemosum RCMB 05922 Geotrichumcandidum RCMB 05097 and Candida albicans RCMB05036) using Amphotericin B 5mgml as a referencecompound [30 45]
(e inhibitory effects of the used ligands and theirternary polymer complexes against the used organisms aregiven in Table 6 In general the used ligands did not displayantifungal or antibacterial inhibitory
For antifungal assay examination and based on theminimum inhibitory concentration (MIC) values it is foundthat the inhibitory effect of all the ternary complexes varyfrom moderate to weak against Amphotericin B controlexcept in the case of Candida albicans (RCMB 05036) whichis not affected by both cobalt and zinc complexes
(e antibacterial activities of the obtained ternarycomplexes are determined in terms of MIC values As shownin Table 6 all complexes display moderate activities againstStreptococcus pneumonia (RCMB 010010) and Bacillis sub-tilis RCMB 010067 (e growth of the gram-negative bac-teria Pseudomonas aeruginosa RCMB 010043 andEscherichia coli RCMB 010052 is extremely affected by bothcopper and nickel complexes which display strong inhibitionagainst the gram-negative pathogenic bacteria with MICvalue less than the Gentamicin control (e remainingcomplexes do not display the same behavior during theassay
342 Cytotoxicity One of the fundamental goals in me-dicinal chemistry is the development of new anticancer andantimicrobial therapeutic agents Cancer treatment usingmetal-based drugs is one of the very effective strategies as themetal ions are capable of binding to nucleic acids stereo-specifically with varying strength
In vitro anticancer activity evaluation of the newlysynthesized compounds was carried out against human
Cou
nts
400
300
200
100
010 20 30 40
Angles (deg2θ)50 60 70
(a)
Cou
nts
100
50
010 20 30 40
Angles (deg2θ)50 60 70
(b)
Figure 7 XRD pattern of (a) copper oxide CuO and (b) cobalt oxide Co3O4 prepared by thermal decomposition at 550Cdeg starting frommetal glutamic arginine mixed ligands complex
Journal of Chemistry 11
cancer cell lines hepatocellular carcinoma (HePG2) becauseliver cancer is the third most common cause of death incancer using MTT method [26 46 47]
Doxorubicin HCl is one of the most effective anti-cancer agents is used as a reference drug in this study (eobtained results from Table 2S indicated that most of thesemoleculesrsquo behavior can be observed from the values of the
half maximal inhibitory concentration IC50 whichfor glutamic and arginine are 167 and 376 μgmlrespectively
IC50 results indicate that the ternary complexes havepromised inhibition of HePG2 liver tumors [48 49]
Cell viability was assessed by themitochondrial-dependentreduction of yellow MTT (3-(45-dimethylthiazol-2-yl)-25-
108K096K084K072K060K048K036K024K012K000K
000 100 200 300 400 500 600 700 800 900
Cu Kβ
Cu Kα
Cu L
O KC K
(a) (b)
Figure 8 EDX and SEM images of CuO obtained by thermal decomposition at 550Cdeg starting from copper glutamic arginine mixed ligandscomplex
135K120K105K090K075K060K045K030K015K000K
000 100 200 300 400 500 600 700 800 900
O K
Co L Co Kα
Co Kβ
(a) (b)
Figure 9 EDX and SEM images of Co3O4 obtained by thermal decomposition at 550Cdeg starting from cobalt glutamic arginine mixedligands complex
Table 6 Antimicrobial activity of prepared ternary metal complexes
Sample tested microorganisms Glutamicacid L-arginine (1) (2) (3) (4) Standard
lowastNA no activity Values in bracket are the MIC values
12 Journal of Chemistry
diphenyl tetrazolium bromide) to insoluble purple formazan[45] (e prepared ternary metal complexes are of differentviability percentages as depicted in Figure 10 Data of bothligands are also included for comparison
Table 2S shows that the ligands have lower inhibition ofHePG2 than their metal ternary complexes (e coppercomplex introduces the highest inhibition
Additionally Table 7 summarizes some computedelectrical reactivity [50] and thermodynamic propertiesfor Co(II) and Cu(II) complexes (as maximum andminimum IC50 of the four prepared ternary metalscomplexes) which are correlated with the inhibition ofhuman cancer cells and are useful to explain the roleplayed by molecular properties in inhibition of humancancer cells
(e simulated data summarized in Table 7 conclude thefollowing
(i) Cu complex is more energetically stable relative toCo complex by about minus265 kJmol
(ii) Cu complex is characterized by lower dipole mo-ment and lower polarizability relative to Co(II)complexes
(iii) Enthalpy and Gibbs free energy of the Cu complexesare more stable by about minus265 kJmol relative toCo(II) complex Lower entropy reflects lower degreeof randomness of Cu(II) complex
(iv) (e chemical potential (μprime) (negative of molecularelectronegativity) of Cu(II) complex is much higherthan that of Co(II) complex reflecting the enhancedreactivity of Cu(II) complex as nucleophile becauseμprime measures the escaping tendency of electrons fromthe complex (μprime (LUMO+HOMO)2) [50]
(v) Cu complex is characterized by lower hardness thanCo(II) complex Hardness measures the resistanceto electron transfer (η (LUMO-HOMO)2) [50]
It seems that more thermodynamically stable and lesspolar Cu complex exhibits that enhanced responsive elec-tron cloud transfer to the surrounding tumor relative to theCo(II) complex (ese quantitative molecular descriptors[50] explain the promising inhibition activity of the Cu(II)complex (e results are correlated with the above-discussedPES results which show that Cu complex could act asnucleophile whereas Co complex is of enhanced electro-philic nature
(e nucleophilicity of Cu complex (seeking for positivelycharged sites of the reactant) together with its electricalthermodynamic and molecular properties favors its prom-ising inhibition activity towards HePG2 cancer cell [51ndash53]
343 Corrosion Inhibition of Aluminum An assessment ofcorrosion rates and inhibition efficiency for aluminum withdifferent inhibitor concentrations were computed as followscorrosion rate Rcorr was computed using equation (5)
Rcorr M1 minusM2( 1113857(mg)
A cm2( ) times t(h) (5)
where M1 weight (g) before immersion M2 weight (g)after immersion A area (cm2) of the specimen andt exposure time (h)
(e inhibition efficiency (IE) was evaluated usingequation (6)
IE Rblank minusRinh
Rblank1113890 1113891 times 100 (6)
120
60
100
80
60
40
20
00 10 20 30 40 50
GlutamicLarginineCu(II)
Ni(II)Co(II)Zn(II)
Figure 10 Cell viability of (HePG2) at different concentrations of ligands and the prepared metal complexes
Table 7 Simulated electrical properties of complexes studied exhibiting enhanced inhibition of HePG2
where Rblank corrosion rates in the absence of inhibitor andRinh corrosion rates in the presence of inhibitor [16]
Table 8 shows the calculated corrosion rates and inhibitionefficiencies of aluminum specimens in aqueous solution of 1MHCl as the corrosive medium in absence and presence ofmixed ligands and their ternary metal complexes at differenttemperatures (293 ndash313) K for 7 hours of each concentrationFigure 6S shows that as the concentration of ligands and theircomplexes increases Rcorr decreases and IE increases formixed ligands and their metal complexes acted as more ef-ficient inhibitors than their mixed ligands alone
344 Adsorption Isotherms and the +ermodynamic Acti-vation Parameters (e metal surface coverage degree(θIE100) was subjected to different adsorption iso-therms (e well fit for weight loss data is obtained forLangmuir adsorption isotherm Figure 11
Table 8 Corrosion parameters for aluminum in aqueous solution of 1M HCl in the absence and presence of different concentrations ofmixed ligands and their metal complexes at different temperatures for 7 hrs
Inhibitors C (times10minus2M)Corrosion rate times10minus4
Figure 11 Langmuir adsorption isotherms of the mixed ligands(L) and their metal complexes
14 Journal of Chemistry
(e temperature effect (293ndash313 K) on aluminum weightloss inhibition may be attributed to two main mechanismsphysical and chemical adsorption [37] (e suggested mech-anisms are obtained as the temperature increases the efficiencydecreases for mixed ligands but increases for their metalcomplexes depending on the nature of bond formation be-tween the mixed ligands and aluminum surface which isdifferent from the nature of bond formation between metalcomplexes and the aluminum surface [16] Arrhenius equation(7) gives the relation between the corrosion rate andtemperature
lnRcorr lnAminusElowast
RT (7)
where A is the Arrhenius factor Elowast is the apparent activationenergy of the corrosion process R is the rate gas constant andT is the absolute temperature (e straight line slope oflogRcorr vs 1T for aluminum 1M HCl at 4times10minus4molL after7 h is minusElowast2303R for the inhibitors (Figure 12)
(e activation thermodynamic parameters for alumi-num dissolution could be obtained from the transition stateequation (8)
lnRcorr
T1113874 1113875 ln
R
Nh1113874 1113875 +
ΔSlowast
R1113888 1113889minus
ΔHlowast
RT1113888 1113889 (8)
where the entropy of activation ∆Slowast and the apparent en-thalpy of activation ∆Hlowast can be obtained from the intercept
3150
02
04
06
logR
corr
(gmiddoth
ndash1middotcm
ndash1)
08
1
12
32 325 331000T(Kndash1)
335 34 345
BlankMix ligandsZn2+
Co2+Ni2+Cu2+
Figure 12 Arrhenius of log corrosion rate (Rcorr) vs 1T for aluminum in 1M HCl without and with 004times10minus2MLminus1 of inhibitors (mixedligands and their metal complexes)
Table 9 (ermodynamic parameters for the adsorption of (004times10minus2)ML mixed ligands and their metal complexes on aluminum metalin aqueous solution of 1M HCl at different temperatures for 7 hrs
and the slope for the straight line of the relation betweenln(RcorrT) vs (1T) respectively N is Avogadrorsquos numberand h is Planckrsquos constant (e Gibbs free energy of acti-vation ∆Glowast can be detected by equation (9)
ΔGlowast ΔHlowast minusTΔSlowast (9)
Table 9 shows the thermodynamic parameters for theadsorption of mixed ligands and their metal complexes (epositive value of ∆Hlowast indicated the endothermic property ofdissolution process nature for aluminum in the acidicmedium [54]
However the blank ΔHlowast value is higher than the in-hibitor metal complexes which indicated that the inhibitionefficiency generally increases with increasing temperature(e association step is the rate-determining step rather thana dissociation process in presence of the metal complexesinhibitors due to the negative values of ΔSlowast It is known thatthe values of ΔGlowast above 40 kJmiddotmolminus1 are referred to chargetransfer from the inhibitor molecules into aluminum surfaceto form coordinated compound on the Al surface whichblocks it against corrosion process by different degrees Alsothe chemical adsorption process mechanism is confirmed bythe values of ΔGlowast above 40 kJmiddotmolminus1 [16 54ndash56]
4 Conclusions
Novel coordination materials of ternary divalent metalions (Cu(II) Ni(II) Co(II) and Zn(II)) chelated by thebidentate glutamic acid (Glu) and L-arginine (Arg) aminoacids are synthesized and characterized (e metal ionscomplexes are modelled using density DFT and TD-DFTtheory Computed molecular and spectroscopic (IR UV-Vis and EPR) properties validated the experimental re-sults (e used computational methods are capable ofproviding good structural descriptions for the TM com-plexes Consistent with the experimental properties theoptimized structures of the complexes [Cu(II) Glu-Arg]and [Co(II) Glu-Arg (H2O)2] reveal that symmetry en-vironment of Cu(II) exhibits slightly distorted squareplanar shape whereas Co(II)-complex has a distortedoctahedral (where Co(II) central ion is of C4v-localsymmetry) Spectral properties of [Ni(II) Glu-Arg(H2O)2] and [ZnmiddotGlumiddotArgmiddot(H2O)2] complexes indicatethat they have similar structure as Co(II) complex All thestudied ternary metal complexes are of different anti-fungal activities ranging from moderate to weak withoutpractically noticed inhibitory effects whereas antibacte-rial activities of all studied metal complexes show sig-nificant effects
Cytotoxicity studies against (HePG2) reveal the prom-ising potentiality of Cu(II) complex as inhibitor of cancercells(e results are correlated with the computed moleculardescriptors including dipole moment polarizability ther-modynamics and reactivity properties as well as the PESmaps
(e corrosion inhibition of aluminum metal specimensin 1M HCl is efficiently achieved by mixed ligands and theirmetal complexes studied
Data Availability
(e data used to support the findings of this study areavailable from the corresponding author upon request
Conflicts of Interest
(e authors declare that they have no conflicts of interest
Supplementary Materials
(e supplementary materials consist of six figures and twotables to further clarify the structures and trends of the newlyprepared metal ternary complexes (SupplementaryMaterials)
References
[1] Z Ozturk D A Kose A Asan et al ldquoPorous metal-organicCu(II) complex of L-Arginine 2synthesis characterizationhydrogen storage properties and molecular simulation cal-culationsrdquo Hittite Journal of Science and Engineering vol 1no 1 pp 1ndash5 2014
[2] S A Lahsasni R A Ammar M F Amin et al ldquoMixed-ligandcomplex formation of Cu(II) with 12- diphenylethylenedi-amine as primary ligand and amino acids as secondary li-gandsrdquo International Journal of Electrochemical Sciencevol 7 pp 7699ndash7711 2012
[3] H Sigel B P Operschall S S Massoud B Song andR Griesser ldquoEvidence for intramolecular aromatic-ringstacking in the physiological pH range of the mono-deprotonated xanthine residue in mixed-ligand complexescontaining xanthosinate 5prime-monophosphate (XMP)rdquo DaltonTransactions vol 46 no 46 pp 5521ndash5529 2006
[4] S Udhayakumar K G Shankar S Sowndarya S VenkateshC Muralidharan and C Rose ldquol-Arginine intercedes bio-crosslinking of a collagen-chitosan 3D-hybrid scaffold fortissue engineering and regeneration in silico in vitro and invivo studiesrdquo RSC Advances vol 7 no 40 pp 25070ndash250882017
[5] P K Datta M Chandra and A K Dey ldquoTernary complexesof copper(II) nickel(II) and zinc(II) with nitrilotriacetic acidas a primary ligand and some phenolic acids as secondaryligandsrdquo Transition Metal Chemistry vol 5 no 1ndash3 1980
[6] J S Woertink L Tian D Maiti et al ldquoSpectroscopic andcomputational studies of an end-on bound superoxo-Cu(II)complex geometric and electronic factors that determine theground staterdquo Inorganic Chemistry vol 49 no 20pp 9450ndash9459 2010
[7] S Dutta S Ray K Nagarajan et al ldquoGlutamic acid analoguesused as potent anticancer a reviewrdquo Der Pharma Chemicavol 3 no 2 pp 263ndash272 2011
[8] T Sismanoglu S Pura and A Bastug ldquoBinary and ternarymetal complexes of Congo red with amino acidsrdquo Dyes andPigments vol 70 no 2 pp 136ndash142 2006
[9] R N Patel H C Pandey K B Pandeya et al ldquoMixed ligandcomplex formation of nickel(II)copper(II) and zinc(II) withsome amino acids and imidazolesrdquo Indian Journal ofChemistry-Section A Inorganic Physical +eoretical andAnalytical Chemistry vol 38 no 8 pp 850ndash853 1999
[10] L Meng and Z Lin ldquoComplexations of alkalialkaline earthmetal cations with gaseous glutamic acidrdquo Computational and+eoretical Chemistry vol 1039 pp 1ndash10 2014
16 Journal of Chemistry
[11] L D Pinto P A L Puppin V M Behring O C AlvesN A Rey and J Felcman ldquoSolution and solid state study ofcopper(II) ternary complexes containing amino acids of in-terest for brain biochemistry-2 homocysteine with aspartateglutamate or methioninerdquo Inorganica Chimica Acta vol 386pp 60ndash67 2012
[12] A Wojciechowska A Ggor and W Zierkiewicz ldquoChiraloctahedral complexes of Co(III) as catalysts for asymmetricepoxidation of chalcones under phase transfer conditionsrdquoRSC Advances vol 5 no 46 pp 36295ndash36306 2015
[13] B M Weckhuysen A A Verberckmoes L Fu andR A Schoonheydt ldquoZeolite-encapsulated copper(II) aminoacid complexes synthesis spectroscopy and catalysisrdquo Journalof Physical Chemistry vol 100 no 22 pp 9456ndash9461 1996
[14] K Y El-Baradie N A El-Wakiel and H A El-GhamryldquoSynthesis characterization and corrosion inhibition in acidmedium ofl-histidine Schiff base complexesrdquo Applied Or-ganometallic Chemistry vol 29 no 3 pp 117ndash125 2015
[15] S S R Anthony and R Susai ldquoInhibition of corrosion ofcarbon steel in well water by arginine-Zn2+ systemrdquo Journal ofElectrochemical Science and Engineering vol 2 no 2pp 91ndash104 2012
[16] E H Isamil F F AlBlewi N Soliman and M M H Khalilldquo(ermal studies and mass loss inhibition for some newmixed amino acid metal complexes with their applicationsrdquoJournal of +ermal Analysis and Calorimetry vol 125 no 1pp 289ndash300 2016
[17] F Neese ldquo(e ORCA program system 4012rdquo Wiley In-terdisciplinary Reviews Computational Molecular Sciencevol 2 no 1 pp 73ndash78 2012
[18] S Grimme S Ehrlich and L Goerigk ldquoEffect of the dampingfunction in dispersion corrected density functional theoryrdquoJournal of Computational Chemistry vol 32 no 7pp 1456ndash1465 2011
[19] S Grimme J Antony S Ehrlich and H Krieg ldquoA consistentand accurate ab initio parametrization of density functionaldispersion correction (DFT-D) for the 94 elements H-Purdquo+e Journal of Chemical Physics vol 132 no 15 article154104 2010
[20] F Weigend ldquoHartree-Fock exchange fitting basis sets for H toRnrdquo Journal of Computational Chemistry vol 29 no 2pp 167ndash175 2008
[21] F Neese F Wennmohs and A Hansen ldquoEfficient ap-proximate and parallel Hartree-Fock and hybrid DFT cal-culations A lsquochain-of-spheresrsquo algorithm for the Hartree-Fock exchangerdquo Chemical Physics vol 356 no 1ndash3pp 98ndash109 2009
[22] R Izsak and F Neese ldquoAn overlap fitted chain of spheresexchange methodrdquo Journal of Chemical Physics vol 135no 14 article 144105 2011
[23] T Petrenko S Kossmann and F Neese ldquoEfficient time-dependent density functional theory approximations forhybrid density functionals analytical gradients and paralle-lizationrdquo Journal of Chemical Physics vol 134 no 5 article054116 2011
[24] A V Marenich C J Cramer and D G Truhlar ldquoUniversalsolvation model based on solute electron density and on acontinuum model of the solvent defined by the bulk dielectricconstant and atomic surface tensionsrdquo Journal of PhysicalChemistry B vol 113 no 18 pp 6378ndash96 2009
[25] S Donovan C Stiefbold and K Sprague ldquoChapter 3Chemical properties of amino acids and identification ofunknown amino acidsrdquo in Proceedings of the 17 thWorkshopConference of the Association for Biology
Laboratory Education (ABLE) vol 17 pp 35ndash70 Bain-bridge GA USA March 1996
[26] C C Wagner J Enrique and C Claudia ldquoVibrational andmagnetic properties of a CuMg glutamate complexrdquoArgentina Acta Farm Bonaerense vol 22 no 2 pp 137ndash1422003
[27] M Arif R Sur and M Arshad ldquoStudies on the thermaldecomposition of copper (II) flouride complexes with variousamino acids in nitrogen atmosphererdquo Turkish Journal ofChemistry vol 25 pp 73ndash79 2001
[28] A Ghosh M J Tucker and R M Hochstrasser ldquoIdentifi-cation of arginine residues in peptides by 2d-IR echo spec-troscopyrdquo Journal of Physical Chemistry A vol 115 no 34pp 9731ndash9738 2011
[29] K Nakamoto Infrared Spectra of Inorganic and CoordinationCompounds Part B Wiley-Interscience New York NY USA5th edition 1997
[30] E Santi M H Torre E Kremer S B Etcheverry andE J Baran ldquoVibrational spectra of the copper(II) and nick-el(II) complexes of piroxicamrdquo Vibrational Spectroscopyvol 5 no 3 pp 285ndash293 1993
[31] H N Aliyu and A S Mohammed ldquoSynthesis spectropho-tometric and biological activity of nickel (II) and copper (II)complexes with schiff base derived from acetylacetone andhistidinerdquo Global Advanced Research Journal of Microbiologyvol 1 no 5 pp 67ndash71 2012
[32] J S Murray and P Politzer ldquo(e electrostatic potential anoverviewrdquo Wiley Interdisciplinary Reviews ComputationalMolecular Science vol 1 no 2 pp 153ndash163 2011
[33] E R Souaya M M H Khalil and E H Ismail ldquoSynthesis andcharacterization of ternary complexes of certain hydroxylacids and their biological applicationsrdquo Research Journal ofPharmaceutical Biological and Chemical Sciences vol 5 no 4pp 18ndash30 2014
[34] N N Greenwood and A Earnshaw A Review of Chemistry ofthe Elements Pergamon Press Oxford UK 1984
[35] V Reddy N Patil and S D Angadi ldquoSynthesis character-ization and antimicrobial activity of Cu(II) Co(II) and Ni(II)complexes with ON and S Donor ligandsrdquo E-Journal ofChemistry vol 5 no 3 pp 577ndash583 2008
[36] F A Cotton G Wilkinson C A Murillo et al Advances inSchiff Base Chemistry Wiley New York NY USA 6th edi-tion 1999
[37] M M H Khalil E H Ismail S A Azim and E R SouayaldquoSynthesis characterization and thermal analysis of ternarycomplexes of nitrilotriacetic acid and alanine or phenylala-nine with some transition metalsrdquo Journal of +ermalAnalysis and Calorimetry vol 101 no 1 pp 129ndash135 2010
[38] F Mabbs and D Colisson Electron Paramagnetic Resonanceof D Transition Metal Compounds Vol 102 ElsevierAmsterdam Netherlands 1992
[39] M M H Khalil E R Souaya E H Ismail et al ldquoTernarytransition metal complexes of nitrilotriacetic acid and valineor leucine synthesis and biological applicationsrdquo ChineseJournal of Inorganic Chemistry vol 29 no 9 pp 1969ndash19782013
[40] I M Weiss C Muth R Drumm and H O K Kirchnerldquo(ermal decomposition of the amino acids glycine cysteineaspartic acid asparagine glutamic acid glutamine arginineand histidinerdquo BMC Biophysics vol 11 no 1 2018
[41] A M Petrosyan V V Ghazaryan G Giester and M FleckldquoSulfamates and methanesulfonates of L-arginine and L-his-tidinerdquo Journal of Molecular Structure vol 1163 pp 114ndash1272018
Journal of Chemistry 17
[42] T Kavitha S Haider T Kamal and M Ul-Islam ldquo(ermaldecomposition of metal complex precursor as route to thesynthesis of Co3O4 nanoparticles antibacterial activity andmechanismrdquo Journal of Alloys and Compounds vol 704pp 296ndash302 2017
[43] E M M Ibrahim L H Abdel-Rahman A M Abu-DiefA Elshafaie S K Hamdan and A M Ahmed ldquo(e synthesisof CuO andNiO nanoparticles by facile thermal decompositionof metal-Schiff base complexes and an examination of theirelectric thermoelectric and magnetic Propertiesrdquo MaterialsResearch Bulletin vol 107 pp 492ndash497 2018
[44] S Farhadi M Javanmard and G Nadri ldquoCharacterization ofcobalt oxide nanoparticles prepared by the thermal de-compositionrdquo Acta Chimica Slovenica vol 63 pp 335ndash3432016
[45] E M Zayed E H Ismail G G Mohamed M M H Khaliland A B Kamel ldquoSynthesis spectroscopic and structuralcharacterization and antimicrobial studies of metal com-plexes of a new hexadentate Schiff base ligand Spectropho-tometric determination of Fe(III) in water samples using arecovery testrdquo Monatshefte fur Chemie-Chemical Monthlyvol 145 no 5 pp 755ndash765 2014
[46] V Milacic D Chen L Ronconi K R Landis-PiwowarD Fregona and Q P Dou ldquoA novel anticancer gold(III)dithiocarbamate compound inhibits the activity of a purified20S proteasome and 26S proteasome in human breast cancercell cultures and xenograftsrdquo Cancer Research vol 66 no 21pp 10478ndash10486 2006
[47] T Mosmann ldquoRapid colorimetric assay for cellular growthand survival application to proliferation and cytotoxicityassaysrdquo Journal of Immunological Methods vol 65 no 1-2pp 55ndash63 1983
[48] R L Siegel K D Miller and A Jemal ldquoCancer statistics2018rdquo CA A Cancer Journal for Clinicians vol 68 no 1pp 7ndash30 2018
[49] S Chattopadhyay S P Chakraborty D Laha et al ldquoSurface-modified cobalt oxide nanoparticles new opportunities foranti-cancer drug developmentrdquo Cancer Nanotechnol vol 3no 1-6 pp 13ndash23 2012
[50] F Zielinski V Tognetti and L Joubert ldquoCondensed de-scriptors for reactivity a methodological studyrdquo ChemicalPhysics Letters vol 527 pp 67ndash72 2012
[51] H Wang Y He Q Yan et al ldquoCorrelation between thedielectric properties and biological activities of human ex vivohepatic tissuerdquo Physics in Medicine and Biology vol 60 no 6pp 2603ndash2617 2015
[52] F Tao F Fu F You et al ldquo(e correlation between dielectricproperties and microstructure of femoral bone in rats withdifferent bone qualitiesrdquo Annals of Biomedical Engineeringvol 42 no 6 pp 1238ndash1249 2014
[53] L Gun D Ning and Z Liang ldquoEffective permittivity ofbiological tissue comparison of theoretical model and ex-perimentrdquo Mathematical Problems in Engineering vol 2017Article ID 7249672 2017
[54] E I Ating S A Umoren I I Udousoro E E Ebenso andA P Udoh ldquoLeaves extract of Ananas sativumas greencorrosion inhibitor for aluminium in hydrochloric acid so-lutionsrdquo Green Chemistry Letters and Reviews vol 3 no 2pp 61ndash68 2010
[55] E Hamed ldquoStudies of the corrosion inhibition of copper inNa2SO4 solution using polarization and electrochemicalimpedance spectroscopyrdquo Materials Chemistry and Physicsvol 121 no 1-2 pp 70ndash76 2010
[56] H Zarrok H Oudda A Zarrouk et al ldquoWeight loss mea-surement and theoretical study of new pyridazine compoundas corrosion inhibitor for C38 steel in hydrochloric acidsolutionrdquo Der Pharma Chemica vol 3 no 6 pp 576ndash5902011
18 Journal of Chemistry
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Submit your manuscripts atwwwhindawicom
Spectral data and assignments are summarized inTable 4
10Dq for the nickel complex was determined by twoprocedures [34]
(e first one is by solving equations (2) and (3) using theenergy terms of the different triplet states transitions sup-plied for Ni(II) [34] as shown in Table 4
(en applying the trial and error procedure a value for∆ that fits in equations (2) and (3) was found to be10935 cmminus1 which suggested the octahedral structure (esecond method for calculating 10Dq used Tanabe andSugano diagrams for the different metal ion complexesFrom Ni(II) diagram we could be able to deduce the ex-pected positions of the (3A2g⟶ 3T2g) and the(3A2g⟶ 3T1g) transitions (is method corresponds to a
pure crystal field approach and assumes that the value ofthe free ion Racah parameter (B) is maintained in thecomplex
Applying this procedure and considering the ratio of ]1]2 1582225641 062 the best vertical line which fulfilsthis ratio cuts the ∆B axis at a value of 139 and Bcomplexis calculated by equation (4) We found the value765273 cmminus1
299
ndash275
299
ndash275
(a)
272
ndash272
272
ndash272
(b)
Figure 3 PES maps (a) Co complex (upper pan solid surfaces and lower pan clipped surfaces) and legend color codes given in kJmol(b) Cu complex (upper pan solid surfaces and lower pan clipped surfaces)
(4) mdash mdash 221 ]1 45249 Charge transfer mdash mdash
Tetragonal distortionpseudosquarepyramidal
(distorted octahedral)
Journal of Chemistry 7
Bcomplex 2v21 + v22 minus 3v1v2( 1113857
15v2 minus 27v1( 1113857 (4)
(en 10Dq 10637253 cmminus1 is compared to the value of10935 cmminus1 obtained by the first method and both valuesconfirm octahedral structure [34] (e magnetic moment ofthe nickel complex was 31 which also confirmed octahedralstructure [16]
Racah parameters for Co(II) complex is also calculatedsimilarly
Furthermore Co(II) complexes have the effectivemagnetic moment μeff 413 (is value is higher than spinonly moment for three unpaired electrons 389 due to aconsiderable orbital contribution [34 36]
(e Zn complex did not show any d-d transitions butdisplayed charge transfer bands as shown in Table 4 (eexistence of charge transfer was due to transition betweentwo different principle quantum numbers from three to fouras distorted tetrahedron being completed by two watermolecules and forms zinc octahedral complex [34ndash37]
(e longest wavelength weak peaks are observed at516 nm (ε middotM 206 Lmiddotmolminus1middotcmminus1) and 636 nm (ε middotM
179 Lmiddotmolminus1middot cmminus1) for Co(II) and Cu(II) complexes re-spectively (e use of TD-DFT at BP86 DEF2-SVP andauxiliary basis DEF2JK level in water (using SMD solvationmodel) [24] results in λmax Co 5291 nm (oscillatorstrength f 0003) and λmax Cu 6486 nm (f 00256)which are in excellent agreement with the experimentalresults
(e computed natural transition orbitals of the longestwavelength transitions in both complexes reveal the largest(greater than 82) contribution of beta HOMO-LUMOwith minor (about 108) contribution of alpha HOMO-LUMO in case of Co(II) complex and about 992 con-tribution from the beta-HOMO-LUMO in case of Cu(II)complex MOs involved in the electronic transitions aredepicted in Figure 5 which illustrate clear dxz or dyz(e)⟶ dz2 (a1) transition in the local square pyramidal(C4v) of Co(II) ion in the Co(II) complex Metaldxy(b2g)minus dx2 minusy2(b1g) transition is dominant in case oflocal square planar symmetry of the Cu(II) complex (is isapproved by low molar absorptivity experimentally ob-served in the UV-Vis spectra of both complexes andsupported by low value of the computed oscillatorstrengths of the forbidden d-d transitions which acquiresome allowness due to geometry distortion of bothcomplexes
314 ESR Spectra For elucidation of the geometry of thecopper ternary complex ESR measurement gives veryuseful information about the stereo chemistry bondingbetween copper and ligands Figure 1S shows the ESRspectrum of the copper complex with a comparativeadvantage and axial symmetry (g || (parallel) 210748g (perpendicular) 201232 (204984) (ese valuesconfirm square planar coordination in which g || gt g gt 2so the unpaired electron found in the dx2 minus y2 orbital andthe ground state is 2B1g [38] (e observed and calculated
g values are different from ge 20023 due to spin-orbitcoupling (e computed g components are not equalreflecting anisotropic effect and the value of g changes as afunction of the orientation of the molecule relative to theexternal magnetic field (is value is close to the spin onlyvalue and it is in a fair agreement with the computed electronspin only value of ge(computed) 20498 [38] Co(II) com-plex is characterized by g 21280 (e simulated EPRspectrum of Co(II) complex returns ge value of 21085
Different values of Mulliken spin density are shown inFigure 4S in such metal-chelates point to purely anisotropiccouplings (e unpaired electron is totally localized onCo(II) ion In case of Cu(II)-complex electron spin pop-ulation is more distributed with about 46 on the Cu(II)ion(is may result in the simulated significant HF couplingin the case of chelating atoms around Cu(II) ion (e datapoint to mixed copper-nitrogen and copper-oxygen bondsin agreement with the computed optimized geometry [38]
32 +ermal Analysis (ermogravimetric analysis (TGA)for the all prepared ternary metal complexes was carried outin nitrogen atmosphere (e thermal decomposition of thefour complexes displayed similar patterns as their ligands
It is well known that amino acids exist only in solid stateso their thermal decomposition has been endothermal be-tween minus72 and minus151 kJmol when heating in range between185degC and 280degC (eir thermal decomposition releasesthree gases mainly H2O less NH3 and hardly any CO2TGA gives the weight of these gases as weight loss calcu-lations which evolve in appreciable amount [39]
Also the thermal decomposition of L-arginine-dopedKDP potassium dihydrogen phosphate crystal started to loseweight with temperature from 341K to 393K releasedammonia and water molecules gases [40]
(e amino acids are totally broken within the range603ndash793K as shown in Figure 6 and Table 5 (e first stepsare weight loss of the three gases H2O NH3 and CO2 withintemperature range about sim423ndash623K (e hydrocarbonsmatter loses weight in the temperature range sim350ndash520degC(e residues for these complexes are mixture with differentratios of metal and metal oxide above temperature range643ndash793K
It is noteworthy to mention that the geometries of thestudied complexes are similar to L-arginine metal complexreported before [41] which have been confirmed by X-raycrystallographic data of single crystals
33 Nanosized Metal Oxides Characterization
331 XRD of Nano CuO and Nano Cobaltosic Oxide(Co3O4) XRD of thermal synthesized copper oxide nano-particles starting from copper glutamic arginine-mixed li-gands complex gives characteristic peaks at 2θ 326deg 356deg387deg 489deg 536deg 582deg 616deg 663deg and 681deg for the markedindices of (110) (002) (111) (202) (020) (202) (113) (022)and (113) respectively as shown in Figure 7(a) which iscomparable with the literature values (e average primaryparticle size of the copper(II) oxide nanoparticles was
8 Journal of Chemistry
TG (m
g)
80
60
40
20
DTG
(mgmiddot
min
ndash1)
000
ndash020
ndash040
ndash060
ndash080
Weight loss ndash1925mgndash24174
Weight loss ndash1745mgndash21914
Weight loss ndash1366mgndash17154
Weight loss ndash0710mgndash8916
Weight loss ndash0276mgndash3466
273 473 673 873 1073 1273Temperature (K)
(a)
273 473 673 873 1073 1273Temperature (K)
TG (m
g)
100
50
DTG
(mgmiddot
min
ndash1)
000
ndash020
ndash040
ndash060
Weight loss ndash1890mgndash14111 Weight loss ndash8641mg
ndash64514
(b)
Figure 6 Continued
Alpha HOMO Alpha LUMO
Beta HOMO Beta LUMO
(a)
Alpha HOMO Alpha LUMO
Beta HOMO Beta LUMO
(b)
Figure 5 Frontier MOs of (a) Co(II) complex and (b) Cu(II) complex involved in the longest wavelength electronic transition Surfacessimilar to that of Co complex are obtained in case of Ni (ere are no d-d transitions in Zn complexes
Journal of Chemistry 9
Table 5 (ermogravimetric analysis decomposition data for the metal ternary complexes
Complexes Mol (wt) TG range (degC) Mass loss () found (calculated) Total mass loss () Assignment
Figure 6 TG and DTG of (a) [Co(glu)(arg)(H2O)2]middot05H2O (b) [Ni(glu)(arg)(H2O)2]middot05H2O (c) [Cu(glu)((arg)]middotH2O and(d) [ZnmiddotGlumiddotArgmiddot(H2O)2]middotH2O
10 Journal of Chemistry
estimated using well-known DebyendashScherrer formula usingthe full width at half maximum (FWHM) of the (111) peaksin the XRD K(α) is the wavelength of X-ray source(15406 A 015406 nm) β∆θ is the full width at halfmaximum (FWHM 01378) and θ 387 is the diffractionangle corresponding to the lattice plane (111) which gives Dsim143ndash204plusmn 08 nm patterns [42ndash44]
(e pattern of XRD for cobalt oxide nanoparticles showscharacteristic peaks at 2θ values at 1898deg 3127deg 3682deg3848deg 4478deg 5568deg 5934deg 6521deg and 7731deg which arecorresponding to their indices (111) (220) (311) (400) (511)and (440) in agreement with JCPDS Card No 76ndash1802 (ispattern confirms the phase formation of cobalt oxidenanoparticle Figure 7(b) (e average size of the Co3O4particles was calculated by the DebyendashScherrer equationDK(α) λ(β cos θ) whereD is the average crystalline size λ isthe wavelength of CuKα θ is Braggrsquos angle and β is the fullwidth at half maximum (FWHM) of the diffraction peak (eaverage dimension D is sim147ndash182plusmn 06 nm at 2θ 3682degwhich is the intense peak [44]
332 EDX of Nano CuO (e synthesized nano copperoxide is confirmed by the EDX spectrum and SEM imagemeasurement shown in Figure 8 which confirms the highestformation percent of CuO and traces of copper carbide (eSEM image for nano copper oxide CuO shows a mixingnanosize 270sim1079 nm [42 43]
333 EDX of Nano Cobaltosic Oxide (e synthesized nanocobalt oxide is confirmed by the EDX spectrum measure-ment shown in Figure 9 which confirms the highest for-mation percent of cobaltosic oxide Co3O4 and traces ofcobalt carbide (e SEM image for nano cobaltosic oxideCo3O4 shows a mixing nanosize 318ndash8543 nm
34 Applications
341 Biological Activity Mixed ligand ternary complexeshave been examined for their in vitro antimicrobial activity(is investigation was performed using the diffusion agartechnique (Figure 5S) (e assays collection included
g-negative (Pseudomonas aeruginosa RCMB 010043 andEscherichia coli RCMB 010052) pathogenic bacteria usingGentamicin 5mgml as a reference compound and g-pos-itive (Streptococcus pneumoniae RCMB 010010 and Bacillissubtilis RCMB 010067) pathogenic bacteria using Ampi-cillin 5mgml as a reference compound It was also in-cluded four fungi (Aspergillus fumigatus RCMB 02568Syncephalastrum racemosum RCMB 05922 Geotrichumcandidum RCMB 05097 and Candida albicans RCMB05036) using Amphotericin B 5mgml as a referencecompound [30 45]
(e inhibitory effects of the used ligands and theirternary polymer complexes against the used organisms aregiven in Table 6 In general the used ligands did not displayantifungal or antibacterial inhibitory
For antifungal assay examination and based on theminimum inhibitory concentration (MIC) values it is foundthat the inhibitory effect of all the ternary complexes varyfrom moderate to weak against Amphotericin B controlexcept in the case of Candida albicans (RCMB 05036) whichis not affected by both cobalt and zinc complexes
(e antibacterial activities of the obtained ternarycomplexes are determined in terms of MIC values As shownin Table 6 all complexes display moderate activities againstStreptococcus pneumonia (RCMB 010010) and Bacillis sub-tilis RCMB 010067 (e growth of the gram-negative bac-teria Pseudomonas aeruginosa RCMB 010043 andEscherichia coli RCMB 010052 is extremely affected by bothcopper and nickel complexes which display strong inhibitionagainst the gram-negative pathogenic bacteria with MICvalue less than the Gentamicin control (e remainingcomplexes do not display the same behavior during theassay
342 Cytotoxicity One of the fundamental goals in me-dicinal chemistry is the development of new anticancer andantimicrobial therapeutic agents Cancer treatment usingmetal-based drugs is one of the very effective strategies as themetal ions are capable of binding to nucleic acids stereo-specifically with varying strength
In vitro anticancer activity evaluation of the newlysynthesized compounds was carried out against human
Cou
nts
400
300
200
100
010 20 30 40
Angles (deg2θ)50 60 70
(a)
Cou
nts
100
50
010 20 30 40
Angles (deg2θ)50 60 70
(b)
Figure 7 XRD pattern of (a) copper oxide CuO and (b) cobalt oxide Co3O4 prepared by thermal decomposition at 550Cdeg starting frommetal glutamic arginine mixed ligands complex
Journal of Chemistry 11
cancer cell lines hepatocellular carcinoma (HePG2) becauseliver cancer is the third most common cause of death incancer using MTT method [26 46 47]
Doxorubicin HCl is one of the most effective anti-cancer agents is used as a reference drug in this study (eobtained results from Table 2S indicated that most of thesemoleculesrsquo behavior can be observed from the values of the
half maximal inhibitory concentration IC50 whichfor glutamic and arginine are 167 and 376 μgmlrespectively
IC50 results indicate that the ternary complexes havepromised inhibition of HePG2 liver tumors [48 49]
Cell viability was assessed by themitochondrial-dependentreduction of yellow MTT (3-(45-dimethylthiazol-2-yl)-25-
108K096K084K072K060K048K036K024K012K000K
000 100 200 300 400 500 600 700 800 900
Cu Kβ
Cu Kα
Cu L
O KC K
(a) (b)
Figure 8 EDX and SEM images of CuO obtained by thermal decomposition at 550Cdeg starting from copper glutamic arginine mixed ligandscomplex
135K120K105K090K075K060K045K030K015K000K
000 100 200 300 400 500 600 700 800 900
O K
Co L Co Kα
Co Kβ
(a) (b)
Figure 9 EDX and SEM images of Co3O4 obtained by thermal decomposition at 550Cdeg starting from cobalt glutamic arginine mixedligands complex
Table 6 Antimicrobial activity of prepared ternary metal complexes
Sample tested microorganisms Glutamicacid L-arginine (1) (2) (3) (4) Standard
lowastNA no activity Values in bracket are the MIC values
12 Journal of Chemistry
diphenyl tetrazolium bromide) to insoluble purple formazan[45] (e prepared ternary metal complexes are of differentviability percentages as depicted in Figure 10 Data of bothligands are also included for comparison
Table 2S shows that the ligands have lower inhibition ofHePG2 than their metal ternary complexes (e coppercomplex introduces the highest inhibition
Additionally Table 7 summarizes some computedelectrical reactivity [50] and thermodynamic propertiesfor Co(II) and Cu(II) complexes (as maximum andminimum IC50 of the four prepared ternary metalscomplexes) which are correlated with the inhibition ofhuman cancer cells and are useful to explain the roleplayed by molecular properties in inhibition of humancancer cells
(e simulated data summarized in Table 7 conclude thefollowing
(i) Cu complex is more energetically stable relative toCo complex by about minus265 kJmol
(ii) Cu complex is characterized by lower dipole mo-ment and lower polarizability relative to Co(II)complexes
(iii) Enthalpy and Gibbs free energy of the Cu complexesare more stable by about minus265 kJmol relative toCo(II) complex Lower entropy reflects lower degreeof randomness of Cu(II) complex
(iv) (e chemical potential (μprime) (negative of molecularelectronegativity) of Cu(II) complex is much higherthan that of Co(II) complex reflecting the enhancedreactivity of Cu(II) complex as nucleophile becauseμprime measures the escaping tendency of electrons fromthe complex (μprime (LUMO+HOMO)2) [50]
(v) Cu complex is characterized by lower hardness thanCo(II) complex Hardness measures the resistanceto electron transfer (η (LUMO-HOMO)2) [50]
It seems that more thermodynamically stable and lesspolar Cu complex exhibits that enhanced responsive elec-tron cloud transfer to the surrounding tumor relative to theCo(II) complex (ese quantitative molecular descriptors[50] explain the promising inhibition activity of the Cu(II)complex (e results are correlated with the above-discussedPES results which show that Cu complex could act asnucleophile whereas Co complex is of enhanced electro-philic nature
(e nucleophilicity of Cu complex (seeking for positivelycharged sites of the reactant) together with its electricalthermodynamic and molecular properties favors its prom-ising inhibition activity towards HePG2 cancer cell [51ndash53]
343 Corrosion Inhibition of Aluminum An assessment ofcorrosion rates and inhibition efficiency for aluminum withdifferent inhibitor concentrations were computed as followscorrosion rate Rcorr was computed using equation (5)
Rcorr M1 minusM2( 1113857(mg)
A cm2( ) times t(h) (5)
where M1 weight (g) before immersion M2 weight (g)after immersion A area (cm2) of the specimen andt exposure time (h)
(e inhibition efficiency (IE) was evaluated usingequation (6)
IE Rblank minusRinh
Rblank1113890 1113891 times 100 (6)
120
60
100
80
60
40
20
00 10 20 30 40 50
GlutamicLarginineCu(II)
Ni(II)Co(II)Zn(II)
Figure 10 Cell viability of (HePG2) at different concentrations of ligands and the prepared metal complexes
Table 7 Simulated electrical properties of complexes studied exhibiting enhanced inhibition of HePG2
where Rblank corrosion rates in the absence of inhibitor andRinh corrosion rates in the presence of inhibitor [16]
Table 8 shows the calculated corrosion rates and inhibitionefficiencies of aluminum specimens in aqueous solution of 1MHCl as the corrosive medium in absence and presence ofmixed ligands and their ternary metal complexes at differenttemperatures (293 ndash313) K for 7 hours of each concentrationFigure 6S shows that as the concentration of ligands and theircomplexes increases Rcorr decreases and IE increases formixed ligands and their metal complexes acted as more ef-ficient inhibitors than their mixed ligands alone
344 Adsorption Isotherms and the +ermodynamic Acti-vation Parameters (e metal surface coverage degree(θIE100) was subjected to different adsorption iso-therms (e well fit for weight loss data is obtained forLangmuir adsorption isotherm Figure 11
Table 8 Corrosion parameters for aluminum in aqueous solution of 1M HCl in the absence and presence of different concentrations ofmixed ligands and their metal complexes at different temperatures for 7 hrs
Inhibitors C (times10minus2M)Corrosion rate times10minus4
Figure 11 Langmuir adsorption isotherms of the mixed ligands(L) and their metal complexes
14 Journal of Chemistry
(e temperature effect (293ndash313 K) on aluminum weightloss inhibition may be attributed to two main mechanismsphysical and chemical adsorption [37] (e suggested mech-anisms are obtained as the temperature increases the efficiencydecreases for mixed ligands but increases for their metalcomplexes depending on the nature of bond formation be-tween the mixed ligands and aluminum surface which isdifferent from the nature of bond formation between metalcomplexes and the aluminum surface [16] Arrhenius equation(7) gives the relation between the corrosion rate andtemperature
lnRcorr lnAminusElowast
RT (7)
where A is the Arrhenius factor Elowast is the apparent activationenergy of the corrosion process R is the rate gas constant andT is the absolute temperature (e straight line slope oflogRcorr vs 1T for aluminum 1M HCl at 4times10minus4molL after7 h is minusElowast2303R for the inhibitors (Figure 12)
(e activation thermodynamic parameters for alumi-num dissolution could be obtained from the transition stateequation (8)
lnRcorr
T1113874 1113875 ln
R
Nh1113874 1113875 +
ΔSlowast
R1113888 1113889minus
ΔHlowast
RT1113888 1113889 (8)
where the entropy of activation ∆Slowast and the apparent en-thalpy of activation ∆Hlowast can be obtained from the intercept
3150
02
04
06
logR
corr
(gmiddoth
ndash1middotcm
ndash1)
08
1
12
32 325 331000T(Kndash1)
335 34 345
BlankMix ligandsZn2+
Co2+Ni2+Cu2+
Figure 12 Arrhenius of log corrosion rate (Rcorr) vs 1T for aluminum in 1M HCl without and with 004times10minus2MLminus1 of inhibitors (mixedligands and their metal complexes)
Table 9 (ermodynamic parameters for the adsorption of (004times10minus2)ML mixed ligands and their metal complexes on aluminum metalin aqueous solution of 1M HCl at different temperatures for 7 hrs
and the slope for the straight line of the relation betweenln(RcorrT) vs (1T) respectively N is Avogadrorsquos numberand h is Planckrsquos constant (e Gibbs free energy of acti-vation ∆Glowast can be detected by equation (9)
ΔGlowast ΔHlowast minusTΔSlowast (9)
Table 9 shows the thermodynamic parameters for theadsorption of mixed ligands and their metal complexes (epositive value of ∆Hlowast indicated the endothermic property ofdissolution process nature for aluminum in the acidicmedium [54]
However the blank ΔHlowast value is higher than the in-hibitor metal complexes which indicated that the inhibitionefficiency generally increases with increasing temperature(e association step is the rate-determining step rather thana dissociation process in presence of the metal complexesinhibitors due to the negative values of ΔSlowast It is known thatthe values of ΔGlowast above 40 kJmiddotmolminus1 are referred to chargetransfer from the inhibitor molecules into aluminum surfaceto form coordinated compound on the Al surface whichblocks it against corrosion process by different degrees Alsothe chemical adsorption process mechanism is confirmed bythe values of ΔGlowast above 40 kJmiddotmolminus1 [16 54ndash56]
4 Conclusions
Novel coordination materials of ternary divalent metalions (Cu(II) Ni(II) Co(II) and Zn(II)) chelated by thebidentate glutamic acid (Glu) and L-arginine (Arg) aminoacids are synthesized and characterized (e metal ionscomplexes are modelled using density DFT and TD-DFTtheory Computed molecular and spectroscopic (IR UV-Vis and EPR) properties validated the experimental re-sults (e used computational methods are capable ofproviding good structural descriptions for the TM com-plexes Consistent with the experimental properties theoptimized structures of the complexes [Cu(II) Glu-Arg]and [Co(II) Glu-Arg (H2O)2] reveal that symmetry en-vironment of Cu(II) exhibits slightly distorted squareplanar shape whereas Co(II)-complex has a distortedoctahedral (where Co(II) central ion is of C4v-localsymmetry) Spectral properties of [Ni(II) Glu-Arg(H2O)2] and [ZnmiddotGlumiddotArgmiddot(H2O)2] complexes indicatethat they have similar structure as Co(II) complex All thestudied ternary metal complexes are of different anti-fungal activities ranging from moderate to weak withoutpractically noticed inhibitory effects whereas antibacte-rial activities of all studied metal complexes show sig-nificant effects
Cytotoxicity studies against (HePG2) reveal the prom-ising potentiality of Cu(II) complex as inhibitor of cancercells(e results are correlated with the computed moleculardescriptors including dipole moment polarizability ther-modynamics and reactivity properties as well as the PESmaps
(e corrosion inhibition of aluminum metal specimensin 1M HCl is efficiently achieved by mixed ligands and theirmetal complexes studied
Data Availability
(e data used to support the findings of this study areavailable from the corresponding author upon request
Conflicts of Interest
(e authors declare that they have no conflicts of interest
Supplementary Materials
(e supplementary materials consist of six figures and twotables to further clarify the structures and trends of the newlyprepared metal ternary complexes (SupplementaryMaterials)
References
[1] Z Ozturk D A Kose A Asan et al ldquoPorous metal-organicCu(II) complex of L-Arginine 2synthesis characterizationhydrogen storage properties and molecular simulation cal-culationsrdquo Hittite Journal of Science and Engineering vol 1no 1 pp 1ndash5 2014
[2] S A Lahsasni R A Ammar M F Amin et al ldquoMixed-ligandcomplex formation of Cu(II) with 12- diphenylethylenedi-amine as primary ligand and amino acids as secondary li-gandsrdquo International Journal of Electrochemical Sciencevol 7 pp 7699ndash7711 2012
[3] H Sigel B P Operschall S S Massoud B Song andR Griesser ldquoEvidence for intramolecular aromatic-ringstacking in the physiological pH range of the mono-deprotonated xanthine residue in mixed-ligand complexescontaining xanthosinate 5prime-monophosphate (XMP)rdquo DaltonTransactions vol 46 no 46 pp 5521ndash5529 2006
[4] S Udhayakumar K G Shankar S Sowndarya S VenkateshC Muralidharan and C Rose ldquol-Arginine intercedes bio-crosslinking of a collagen-chitosan 3D-hybrid scaffold fortissue engineering and regeneration in silico in vitro and invivo studiesrdquo RSC Advances vol 7 no 40 pp 25070ndash250882017
[5] P K Datta M Chandra and A K Dey ldquoTernary complexesof copper(II) nickel(II) and zinc(II) with nitrilotriacetic acidas a primary ligand and some phenolic acids as secondaryligandsrdquo Transition Metal Chemistry vol 5 no 1ndash3 1980
[6] J S Woertink L Tian D Maiti et al ldquoSpectroscopic andcomputational studies of an end-on bound superoxo-Cu(II)complex geometric and electronic factors that determine theground staterdquo Inorganic Chemistry vol 49 no 20pp 9450ndash9459 2010
[7] S Dutta S Ray K Nagarajan et al ldquoGlutamic acid analoguesused as potent anticancer a reviewrdquo Der Pharma Chemicavol 3 no 2 pp 263ndash272 2011
[8] T Sismanoglu S Pura and A Bastug ldquoBinary and ternarymetal complexes of Congo red with amino acidsrdquo Dyes andPigments vol 70 no 2 pp 136ndash142 2006
[9] R N Patel H C Pandey K B Pandeya et al ldquoMixed ligandcomplex formation of nickel(II)copper(II) and zinc(II) withsome amino acids and imidazolesrdquo Indian Journal ofChemistry-Section A Inorganic Physical +eoretical andAnalytical Chemistry vol 38 no 8 pp 850ndash853 1999
[10] L Meng and Z Lin ldquoComplexations of alkalialkaline earthmetal cations with gaseous glutamic acidrdquo Computational and+eoretical Chemistry vol 1039 pp 1ndash10 2014
16 Journal of Chemistry
[11] L D Pinto P A L Puppin V M Behring O C AlvesN A Rey and J Felcman ldquoSolution and solid state study ofcopper(II) ternary complexes containing amino acids of in-terest for brain biochemistry-2 homocysteine with aspartateglutamate or methioninerdquo Inorganica Chimica Acta vol 386pp 60ndash67 2012
[12] A Wojciechowska A Ggor and W Zierkiewicz ldquoChiraloctahedral complexes of Co(III) as catalysts for asymmetricepoxidation of chalcones under phase transfer conditionsrdquoRSC Advances vol 5 no 46 pp 36295ndash36306 2015
[13] B M Weckhuysen A A Verberckmoes L Fu andR A Schoonheydt ldquoZeolite-encapsulated copper(II) aminoacid complexes synthesis spectroscopy and catalysisrdquo Journalof Physical Chemistry vol 100 no 22 pp 9456ndash9461 1996
[14] K Y El-Baradie N A El-Wakiel and H A El-GhamryldquoSynthesis characterization and corrosion inhibition in acidmedium ofl-histidine Schiff base complexesrdquo Applied Or-ganometallic Chemistry vol 29 no 3 pp 117ndash125 2015
[15] S S R Anthony and R Susai ldquoInhibition of corrosion ofcarbon steel in well water by arginine-Zn2+ systemrdquo Journal ofElectrochemical Science and Engineering vol 2 no 2pp 91ndash104 2012
[16] E H Isamil F F AlBlewi N Soliman and M M H Khalilldquo(ermal studies and mass loss inhibition for some newmixed amino acid metal complexes with their applicationsrdquoJournal of +ermal Analysis and Calorimetry vol 125 no 1pp 289ndash300 2016
[17] F Neese ldquo(e ORCA program system 4012rdquo Wiley In-terdisciplinary Reviews Computational Molecular Sciencevol 2 no 1 pp 73ndash78 2012
[18] S Grimme S Ehrlich and L Goerigk ldquoEffect of the dampingfunction in dispersion corrected density functional theoryrdquoJournal of Computational Chemistry vol 32 no 7pp 1456ndash1465 2011
[19] S Grimme J Antony S Ehrlich and H Krieg ldquoA consistentand accurate ab initio parametrization of density functionaldispersion correction (DFT-D) for the 94 elements H-Purdquo+e Journal of Chemical Physics vol 132 no 15 article154104 2010
[20] F Weigend ldquoHartree-Fock exchange fitting basis sets for H toRnrdquo Journal of Computational Chemistry vol 29 no 2pp 167ndash175 2008
[21] F Neese F Wennmohs and A Hansen ldquoEfficient ap-proximate and parallel Hartree-Fock and hybrid DFT cal-culations A lsquochain-of-spheresrsquo algorithm for the Hartree-Fock exchangerdquo Chemical Physics vol 356 no 1ndash3pp 98ndash109 2009
[22] R Izsak and F Neese ldquoAn overlap fitted chain of spheresexchange methodrdquo Journal of Chemical Physics vol 135no 14 article 144105 2011
[23] T Petrenko S Kossmann and F Neese ldquoEfficient time-dependent density functional theory approximations forhybrid density functionals analytical gradients and paralle-lizationrdquo Journal of Chemical Physics vol 134 no 5 article054116 2011
[24] A V Marenich C J Cramer and D G Truhlar ldquoUniversalsolvation model based on solute electron density and on acontinuum model of the solvent defined by the bulk dielectricconstant and atomic surface tensionsrdquo Journal of PhysicalChemistry B vol 113 no 18 pp 6378ndash96 2009
[25] S Donovan C Stiefbold and K Sprague ldquoChapter 3Chemical properties of amino acids and identification ofunknown amino acidsrdquo in Proceedings of the 17 thWorkshopConference of the Association for Biology
Laboratory Education (ABLE) vol 17 pp 35ndash70 Bain-bridge GA USA March 1996
[26] C C Wagner J Enrique and C Claudia ldquoVibrational andmagnetic properties of a CuMg glutamate complexrdquoArgentina Acta Farm Bonaerense vol 22 no 2 pp 137ndash1422003
[27] M Arif R Sur and M Arshad ldquoStudies on the thermaldecomposition of copper (II) flouride complexes with variousamino acids in nitrogen atmosphererdquo Turkish Journal ofChemistry vol 25 pp 73ndash79 2001
[28] A Ghosh M J Tucker and R M Hochstrasser ldquoIdentifi-cation of arginine residues in peptides by 2d-IR echo spec-troscopyrdquo Journal of Physical Chemistry A vol 115 no 34pp 9731ndash9738 2011
[29] K Nakamoto Infrared Spectra of Inorganic and CoordinationCompounds Part B Wiley-Interscience New York NY USA5th edition 1997
[30] E Santi M H Torre E Kremer S B Etcheverry andE J Baran ldquoVibrational spectra of the copper(II) and nick-el(II) complexes of piroxicamrdquo Vibrational Spectroscopyvol 5 no 3 pp 285ndash293 1993
[31] H N Aliyu and A S Mohammed ldquoSynthesis spectropho-tometric and biological activity of nickel (II) and copper (II)complexes with schiff base derived from acetylacetone andhistidinerdquo Global Advanced Research Journal of Microbiologyvol 1 no 5 pp 67ndash71 2012
[32] J S Murray and P Politzer ldquo(e electrostatic potential anoverviewrdquo Wiley Interdisciplinary Reviews ComputationalMolecular Science vol 1 no 2 pp 153ndash163 2011
[33] E R Souaya M M H Khalil and E H Ismail ldquoSynthesis andcharacterization of ternary complexes of certain hydroxylacids and their biological applicationsrdquo Research Journal ofPharmaceutical Biological and Chemical Sciences vol 5 no 4pp 18ndash30 2014
[34] N N Greenwood and A Earnshaw A Review of Chemistry ofthe Elements Pergamon Press Oxford UK 1984
[35] V Reddy N Patil and S D Angadi ldquoSynthesis character-ization and antimicrobial activity of Cu(II) Co(II) and Ni(II)complexes with ON and S Donor ligandsrdquo E-Journal ofChemistry vol 5 no 3 pp 577ndash583 2008
[36] F A Cotton G Wilkinson C A Murillo et al Advances inSchiff Base Chemistry Wiley New York NY USA 6th edi-tion 1999
[37] M M H Khalil E H Ismail S A Azim and E R SouayaldquoSynthesis characterization and thermal analysis of ternarycomplexes of nitrilotriacetic acid and alanine or phenylala-nine with some transition metalsrdquo Journal of +ermalAnalysis and Calorimetry vol 101 no 1 pp 129ndash135 2010
[38] F Mabbs and D Colisson Electron Paramagnetic Resonanceof D Transition Metal Compounds Vol 102 ElsevierAmsterdam Netherlands 1992
[39] M M H Khalil E R Souaya E H Ismail et al ldquoTernarytransition metal complexes of nitrilotriacetic acid and valineor leucine synthesis and biological applicationsrdquo ChineseJournal of Inorganic Chemistry vol 29 no 9 pp 1969ndash19782013
[40] I M Weiss C Muth R Drumm and H O K Kirchnerldquo(ermal decomposition of the amino acids glycine cysteineaspartic acid asparagine glutamic acid glutamine arginineand histidinerdquo BMC Biophysics vol 11 no 1 2018
[41] A M Petrosyan V V Ghazaryan G Giester and M FleckldquoSulfamates and methanesulfonates of L-arginine and L-his-tidinerdquo Journal of Molecular Structure vol 1163 pp 114ndash1272018
Journal of Chemistry 17
[42] T Kavitha S Haider T Kamal and M Ul-Islam ldquo(ermaldecomposition of metal complex precursor as route to thesynthesis of Co3O4 nanoparticles antibacterial activity andmechanismrdquo Journal of Alloys and Compounds vol 704pp 296ndash302 2017
[43] E M M Ibrahim L H Abdel-Rahman A M Abu-DiefA Elshafaie S K Hamdan and A M Ahmed ldquo(e synthesisof CuO andNiO nanoparticles by facile thermal decompositionof metal-Schiff base complexes and an examination of theirelectric thermoelectric and magnetic Propertiesrdquo MaterialsResearch Bulletin vol 107 pp 492ndash497 2018
[44] S Farhadi M Javanmard and G Nadri ldquoCharacterization ofcobalt oxide nanoparticles prepared by the thermal de-compositionrdquo Acta Chimica Slovenica vol 63 pp 335ndash3432016
[45] E M Zayed E H Ismail G G Mohamed M M H Khaliland A B Kamel ldquoSynthesis spectroscopic and structuralcharacterization and antimicrobial studies of metal com-plexes of a new hexadentate Schiff base ligand Spectropho-tometric determination of Fe(III) in water samples using arecovery testrdquo Monatshefte fur Chemie-Chemical Monthlyvol 145 no 5 pp 755ndash765 2014
[46] V Milacic D Chen L Ronconi K R Landis-PiwowarD Fregona and Q P Dou ldquoA novel anticancer gold(III)dithiocarbamate compound inhibits the activity of a purified20S proteasome and 26S proteasome in human breast cancercell cultures and xenograftsrdquo Cancer Research vol 66 no 21pp 10478ndash10486 2006
[47] T Mosmann ldquoRapid colorimetric assay for cellular growthand survival application to proliferation and cytotoxicityassaysrdquo Journal of Immunological Methods vol 65 no 1-2pp 55ndash63 1983
[48] R L Siegel K D Miller and A Jemal ldquoCancer statistics2018rdquo CA A Cancer Journal for Clinicians vol 68 no 1pp 7ndash30 2018
[49] S Chattopadhyay S P Chakraborty D Laha et al ldquoSurface-modified cobalt oxide nanoparticles new opportunities foranti-cancer drug developmentrdquo Cancer Nanotechnol vol 3no 1-6 pp 13ndash23 2012
[50] F Zielinski V Tognetti and L Joubert ldquoCondensed de-scriptors for reactivity a methodological studyrdquo ChemicalPhysics Letters vol 527 pp 67ndash72 2012
[51] H Wang Y He Q Yan et al ldquoCorrelation between thedielectric properties and biological activities of human ex vivohepatic tissuerdquo Physics in Medicine and Biology vol 60 no 6pp 2603ndash2617 2015
[52] F Tao F Fu F You et al ldquo(e correlation between dielectricproperties and microstructure of femoral bone in rats withdifferent bone qualitiesrdquo Annals of Biomedical Engineeringvol 42 no 6 pp 1238ndash1249 2014
[53] L Gun D Ning and Z Liang ldquoEffective permittivity ofbiological tissue comparison of theoretical model and ex-perimentrdquo Mathematical Problems in Engineering vol 2017Article ID 7249672 2017
[54] E I Ating S A Umoren I I Udousoro E E Ebenso andA P Udoh ldquoLeaves extract of Ananas sativumas greencorrosion inhibitor for aluminium in hydrochloric acid so-lutionsrdquo Green Chemistry Letters and Reviews vol 3 no 2pp 61ndash68 2010
[55] E Hamed ldquoStudies of the corrosion inhibition of copper inNa2SO4 solution using polarization and electrochemicalimpedance spectroscopyrdquo Materials Chemistry and Physicsvol 121 no 1-2 pp 70ndash76 2010
[56] H Zarrok H Oudda A Zarrouk et al ldquoWeight loss mea-surement and theoretical study of new pyridazine compoundas corrosion inhibitor for C38 steel in hydrochloric acidsolutionrdquo Der Pharma Chemica vol 3 no 6 pp 576ndash5902011
18 Journal of Chemistry
TribologyAdvances in
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
International Journal ofInternational Journal ofPhotoenergy
Hindawiwwwhindawicom Volume 2018
Journal of
Chemistry
Hindawiwwwhindawicom Volume 2018
Advances inPhysical Chemistry
Hindawiwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2018
Bioinorganic Chemistry and ApplicationsHindawiwwwhindawicom Volume 2018
(4) mdash mdash 221 ]1 45249 Charge transfer mdash mdash
Tetragonal distortionpseudosquarepyramidal
(distorted octahedral)
Journal of Chemistry 7
Bcomplex 2v21 + v22 minus 3v1v2( 1113857
15v2 minus 27v1( 1113857 (4)
(en 10Dq 10637253 cmminus1 is compared to the value of10935 cmminus1 obtained by the first method and both valuesconfirm octahedral structure [34] (e magnetic moment ofthe nickel complex was 31 which also confirmed octahedralstructure [16]
Racah parameters for Co(II) complex is also calculatedsimilarly
Furthermore Co(II) complexes have the effectivemagnetic moment μeff 413 (is value is higher than spinonly moment for three unpaired electrons 389 due to aconsiderable orbital contribution [34 36]
(e Zn complex did not show any d-d transitions butdisplayed charge transfer bands as shown in Table 4 (eexistence of charge transfer was due to transition betweentwo different principle quantum numbers from three to fouras distorted tetrahedron being completed by two watermolecules and forms zinc octahedral complex [34ndash37]
(e longest wavelength weak peaks are observed at516 nm (ε middotM 206 Lmiddotmolminus1middotcmminus1) and 636 nm (ε middotM
179 Lmiddotmolminus1middot cmminus1) for Co(II) and Cu(II) complexes re-spectively (e use of TD-DFT at BP86 DEF2-SVP andauxiliary basis DEF2JK level in water (using SMD solvationmodel) [24] results in λmax Co 5291 nm (oscillatorstrength f 0003) and λmax Cu 6486 nm (f 00256)which are in excellent agreement with the experimentalresults
(e computed natural transition orbitals of the longestwavelength transitions in both complexes reveal the largest(greater than 82) contribution of beta HOMO-LUMOwith minor (about 108) contribution of alpha HOMO-LUMO in case of Co(II) complex and about 992 con-tribution from the beta-HOMO-LUMO in case of Cu(II)complex MOs involved in the electronic transitions aredepicted in Figure 5 which illustrate clear dxz or dyz(e)⟶ dz2 (a1) transition in the local square pyramidal(C4v) of Co(II) ion in the Co(II) complex Metaldxy(b2g)minus dx2 minusy2(b1g) transition is dominant in case oflocal square planar symmetry of the Cu(II) complex (is isapproved by low molar absorptivity experimentally ob-served in the UV-Vis spectra of both complexes andsupported by low value of the computed oscillatorstrengths of the forbidden d-d transitions which acquiresome allowness due to geometry distortion of bothcomplexes
314 ESR Spectra For elucidation of the geometry of thecopper ternary complex ESR measurement gives veryuseful information about the stereo chemistry bondingbetween copper and ligands Figure 1S shows the ESRspectrum of the copper complex with a comparativeadvantage and axial symmetry (g || (parallel) 210748g (perpendicular) 201232 (204984) (ese valuesconfirm square planar coordination in which g || gt g gt 2so the unpaired electron found in the dx2 minus y2 orbital andthe ground state is 2B1g [38] (e observed and calculated
g values are different from ge 20023 due to spin-orbitcoupling (e computed g components are not equalreflecting anisotropic effect and the value of g changes as afunction of the orientation of the molecule relative to theexternal magnetic field (is value is close to the spin onlyvalue and it is in a fair agreement with the computed electronspin only value of ge(computed) 20498 [38] Co(II) com-plex is characterized by g 21280 (e simulated EPRspectrum of Co(II) complex returns ge value of 21085
Different values of Mulliken spin density are shown inFigure 4S in such metal-chelates point to purely anisotropiccouplings (e unpaired electron is totally localized onCo(II) ion In case of Cu(II)-complex electron spin pop-ulation is more distributed with about 46 on the Cu(II)ion(is may result in the simulated significant HF couplingin the case of chelating atoms around Cu(II) ion (e datapoint to mixed copper-nitrogen and copper-oxygen bondsin agreement with the computed optimized geometry [38]
32 +ermal Analysis (ermogravimetric analysis (TGA)for the all prepared ternary metal complexes was carried outin nitrogen atmosphere (e thermal decomposition of thefour complexes displayed similar patterns as their ligands
It is well known that amino acids exist only in solid stateso their thermal decomposition has been endothermal be-tween minus72 and minus151 kJmol when heating in range between185degC and 280degC (eir thermal decomposition releasesthree gases mainly H2O less NH3 and hardly any CO2TGA gives the weight of these gases as weight loss calcu-lations which evolve in appreciable amount [39]
Also the thermal decomposition of L-arginine-dopedKDP potassium dihydrogen phosphate crystal started to loseweight with temperature from 341K to 393K releasedammonia and water molecules gases [40]
(e amino acids are totally broken within the range603ndash793K as shown in Figure 6 and Table 5 (e first stepsare weight loss of the three gases H2O NH3 and CO2 withintemperature range about sim423ndash623K (e hydrocarbonsmatter loses weight in the temperature range sim350ndash520degC(e residues for these complexes are mixture with differentratios of metal and metal oxide above temperature range643ndash793K
It is noteworthy to mention that the geometries of thestudied complexes are similar to L-arginine metal complexreported before [41] which have been confirmed by X-raycrystallographic data of single crystals
33 Nanosized Metal Oxides Characterization
331 XRD of Nano CuO and Nano Cobaltosic Oxide(Co3O4) XRD of thermal synthesized copper oxide nano-particles starting from copper glutamic arginine-mixed li-gands complex gives characteristic peaks at 2θ 326deg 356deg387deg 489deg 536deg 582deg 616deg 663deg and 681deg for the markedindices of (110) (002) (111) (202) (020) (202) (113) (022)and (113) respectively as shown in Figure 7(a) which iscomparable with the literature values (e average primaryparticle size of the copper(II) oxide nanoparticles was
8 Journal of Chemistry
TG (m
g)
80
60
40
20
DTG
(mgmiddot
min
ndash1)
000
ndash020
ndash040
ndash060
ndash080
Weight loss ndash1925mgndash24174
Weight loss ndash1745mgndash21914
Weight loss ndash1366mgndash17154
Weight loss ndash0710mgndash8916
Weight loss ndash0276mgndash3466
273 473 673 873 1073 1273Temperature (K)
(a)
273 473 673 873 1073 1273Temperature (K)
TG (m
g)
100
50
DTG
(mgmiddot
min
ndash1)
000
ndash020
ndash040
ndash060
Weight loss ndash1890mgndash14111 Weight loss ndash8641mg
ndash64514
(b)
Figure 6 Continued
Alpha HOMO Alpha LUMO
Beta HOMO Beta LUMO
(a)
Alpha HOMO Alpha LUMO
Beta HOMO Beta LUMO
(b)
Figure 5 Frontier MOs of (a) Co(II) complex and (b) Cu(II) complex involved in the longest wavelength electronic transition Surfacessimilar to that of Co complex are obtained in case of Ni (ere are no d-d transitions in Zn complexes
Journal of Chemistry 9
Table 5 (ermogravimetric analysis decomposition data for the metal ternary complexes
Complexes Mol (wt) TG range (degC) Mass loss () found (calculated) Total mass loss () Assignment
Figure 6 TG and DTG of (a) [Co(glu)(arg)(H2O)2]middot05H2O (b) [Ni(glu)(arg)(H2O)2]middot05H2O (c) [Cu(glu)((arg)]middotH2O and(d) [ZnmiddotGlumiddotArgmiddot(H2O)2]middotH2O
10 Journal of Chemistry
estimated using well-known DebyendashScherrer formula usingthe full width at half maximum (FWHM) of the (111) peaksin the XRD K(α) is the wavelength of X-ray source(15406 A 015406 nm) β∆θ is the full width at halfmaximum (FWHM 01378) and θ 387 is the diffractionangle corresponding to the lattice plane (111) which gives Dsim143ndash204plusmn 08 nm patterns [42ndash44]
(e pattern of XRD for cobalt oxide nanoparticles showscharacteristic peaks at 2θ values at 1898deg 3127deg 3682deg3848deg 4478deg 5568deg 5934deg 6521deg and 7731deg which arecorresponding to their indices (111) (220) (311) (400) (511)and (440) in agreement with JCPDS Card No 76ndash1802 (ispattern confirms the phase formation of cobalt oxidenanoparticle Figure 7(b) (e average size of the Co3O4particles was calculated by the DebyendashScherrer equationDK(α) λ(β cos θ) whereD is the average crystalline size λ isthe wavelength of CuKα θ is Braggrsquos angle and β is the fullwidth at half maximum (FWHM) of the diffraction peak (eaverage dimension D is sim147ndash182plusmn 06 nm at 2θ 3682degwhich is the intense peak [44]
332 EDX of Nano CuO (e synthesized nano copperoxide is confirmed by the EDX spectrum and SEM imagemeasurement shown in Figure 8 which confirms the highestformation percent of CuO and traces of copper carbide (eSEM image for nano copper oxide CuO shows a mixingnanosize 270sim1079 nm [42 43]
333 EDX of Nano Cobaltosic Oxide (e synthesized nanocobalt oxide is confirmed by the EDX spectrum measure-ment shown in Figure 9 which confirms the highest for-mation percent of cobaltosic oxide Co3O4 and traces ofcobalt carbide (e SEM image for nano cobaltosic oxideCo3O4 shows a mixing nanosize 318ndash8543 nm
34 Applications
341 Biological Activity Mixed ligand ternary complexeshave been examined for their in vitro antimicrobial activity(is investigation was performed using the diffusion agartechnique (Figure 5S) (e assays collection included
g-negative (Pseudomonas aeruginosa RCMB 010043 andEscherichia coli RCMB 010052) pathogenic bacteria usingGentamicin 5mgml as a reference compound and g-pos-itive (Streptococcus pneumoniae RCMB 010010 and Bacillissubtilis RCMB 010067) pathogenic bacteria using Ampi-cillin 5mgml as a reference compound It was also in-cluded four fungi (Aspergillus fumigatus RCMB 02568Syncephalastrum racemosum RCMB 05922 Geotrichumcandidum RCMB 05097 and Candida albicans RCMB05036) using Amphotericin B 5mgml as a referencecompound [30 45]
(e inhibitory effects of the used ligands and theirternary polymer complexes against the used organisms aregiven in Table 6 In general the used ligands did not displayantifungal or antibacterial inhibitory
For antifungal assay examination and based on theminimum inhibitory concentration (MIC) values it is foundthat the inhibitory effect of all the ternary complexes varyfrom moderate to weak against Amphotericin B controlexcept in the case of Candida albicans (RCMB 05036) whichis not affected by both cobalt and zinc complexes
(e antibacterial activities of the obtained ternarycomplexes are determined in terms of MIC values As shownin Table 6 all complexes display moderate activities againstStreptococcus pneumonia (RCMB 010010) and Bacillis sub-tilis RCMB 010067 (e growth of the gram-negative bac-teria Pseudomonas aeruginosa RCMB 010043 andEscherichia coli RCMB 010052 is extremely affected by bothcopper and nickel complexes which display strong inhibitionagainst the gram-negative pathogenic bacteria with MICvalue less than the Gentamicin control (e remainingcomplexes do not display the same behavior during theassay
342 Cytotoxicity One of the fundamental goals in me-dicinal chemistry is the development of new anticancer andantimicrobial therapeutic agents Cancer treatment usingmetal-based drugs is one of the very effective strategies as themetal ions are capable of binding to nucleic acids stereo-specifically with varying strength
In vitro anticancer activity evaluation of the newlysynthesized compounds was carried out against human
Cou
nts
400
300
200
100
010 20 30 40
Angles (deg2θ)50 60 70
(a)
Cou
nts
100
50
010 20 30 40
Angles (deg2θ)50 60 70
(b)
Figure 7 XRD pattern of (a) copper oxide CuO and (b) cobalt oxide Co3O4 prepared by thermal decomposition at 550Cdeg starting frommetal glutamic arginine mixed ligands complex
Journal of Chemistry 11
cancer cell lines hepatocellular carcinoma (HePG2) becauseliver cancer is the third most common cause of death incancer using MTT method [26 46 47]
Doxorubicin HCl is one of the most effective anti-cancer agents is used as a reference drug in this study (eobtained results from Table 2S indicated that most of thesemoleculesrsquo behavior can be observed from the values of the
half maximal inhibitory concentration IC50 whichfor glutamic and arginine are 167 and 376 μgmlrespectively
IC50 results indicate that the ternary complexes havepromised inhibition of HePG2 liver tumors [48 49]
Cell viability was assessed by themitochondrial-dependentreduction of yellow MTT (3-(45-dimethylthiazol-2-yl)-25-
108K096K084K072K060K048K036K024K012K000K
000 100 200 300 400 500 600 700 800 900
Cu Kβ
Cu Kα
Cu L
O KC K
(a) (b)
Figure 8 EDX and SEM images of CuO obtained by thermal decomposition at 550Cdeg starting from copper glutamic arginine mixed ligandscomplex
135K120K105K090K075K060K045K030K015K000K
000 100 200 300 400 500 600 700 800 900
O K
Co L Co Kα
Co Kβ
(a) (b)
Figure 9 EDX and SEM images of Co3O4 obtained by thermal decomposition at 550Cdeg starting from cobalt glutamic arginine mixedligands complex
Table 6 Antimicrobial activity of prepared ternary metal complexes
Sample tested microorganisms Glutamicacid L-arginine (1) (2) (3) (4) Standard
lowastNA no activity Values in bracket are the MIC values
12 Journal of Chemistry
diphenyl tetrazolium bromide) to insoluble purple formazan[45] (e prepared ternary metal complexes are of differentviability percentages as depicted in Figure 10 Data of bothligands are also included for comparison
Table 2S shows that the ligands have lower inhibition ofHePG2 than their metal ternary complexes (e coppercomplex introduces the highest inhibition
Additionally Table 7 summarizes some computedelectrical reactivity [50] and thermodynamic propertiesfor Co(II) and Cu(II) complexes (as maximum andminimum IC50 of the four prepared ternary metalscomplexes) which are correlated with the inhibition ofhuman cancer cells and are useful to explain the roleplayed by molecular properties in inhibition of humancancer cells
(e simulated data summarized in Table 7 conclude thefollowing
(i) Cu complex is more energetically stable relative toCo complex by about minus265 kJmol
(ii) Cu complex is characterized by lower dipole mo-ment and lower polarizability relative to Co(II)complexes
(iii) Enthalpy and Gibbs free energy of the Cu complexesare more stable by about minus265 kJmol relative toCo(II) complex Lower entropy reflects lower degreeof randomness of Cu(II) complex
(iv) (e chemical potential (μprime) (negative of molecularelectronegativity) of Cu(II) complex is much higherthan that of Co(II) complex reflecting the enhancedreactivity of Cu(II) complex as nucleophile becauseμprime measures the escaping tendency of electrons fromthe complex (μprime (LUMO+HOMO)2) [50]
(v) Cu complex is characterized by lower hardness thanCo(II) complex Hardness measures the resistanceto electron transfer (η (LUMO-HOMO)2) [50]
It seems that more thermodynamically stable and lesspolar Cu complex exhibits that enhanced responsive elec-tron cloud transfer to the surrounding tumor relative to theCo(II) complex (ese quantitative molecular descriptors[50] explain the promising inhibition activity of the Cu(II)complex (e results are correlated with the above-discussedPES results which show that Cu complex could act asnucleophile whereas Co complex is of enhanced electro-philic nature
(e nucleophilicity of Cu complex (seeking for positivelycharged sites of the reactant) together with its electricalthermodynamic and molecular properties favors its prom-ising inhibition activity towards HePG2 cancer cell [51ndash53]
343 Corrosion Inhibition of Aluminum An assessment ofcorrosion rates and inhibition efficiency for aluminum withdifferent inhibitor concentrations were computed as followscorrosion rate Rcorr was computed using equation (5)
Rcorr M1 minusM2( 1113857(mg)
A cm2( ) times t(h) (5)
where M1 weight (g) before immersion M2 weight (g)after immersion A area (cm2) of the specimen andt exposure time (h)
(e inhibition efficiency (IE) was evaluated usingequation (6)
IE Rblank minusRinh
Rblank1113890 1113891 times 100 (6)
120
60
100
80
60
40
20
00 10 20 30 40 50
GlutamicLarginineCu(II)
Ni(II)Co(II)Zn(II)
Figure 10 Cell viability of (HePG2) at different concentrations of ligands and the prepared metal complexes
Table 7 Simulated electrical properties of complexes studied exhibiting enhanced inhibition of HePG2
where Rblank corrosion rates in the absence of inhibitor andRinh corrosion rates in the presence of inhibitor [16]
Table 8 shows the calculated corrosion rates and inhibitionefficiencies of aluminum specimens in aqueous solution of 1MHCl as the corrosive medium in absence and presence ofmixed ligands and their ternary metal complexes at differenttemperatures (293 ndash313) K for 7 hours of each concentrationFigure 6S shows that as the concentration of ligands and theircomplexes increases Rcorr decreases and IE increases formixed ligands and their metal complexes acted as more ef-ficient inhibitors than their mixed ligands alone
344 Adsorption Isotherms and the +ermodynamic Acti-vation Parameters (e metal surface coverage degree(θIE100) was subjected to different adsorption iso-therms (e well fit for weight loss data is obtained forLangmuir adsorption isotherm Figure 11
Table 8 Corrosion parameters for aluminum in aqueous solution of 1M HCl in the absence and presence of different concentrations ofmixed ligands and their metal complexes at different temperatures for 7 hrs
Inhibitors C (times10minus2M)Corrosion rate times10minus4
Figure 11 Langmuir adsorption isotherms of the mixed ligands(L) and their metal complexes
14 Journal of Chemistry
(e temperature effect (293ndash313 K) on aluminum weightloss inhibition may be attributed to two main mechanismsphysical and chemical adsorption [37] (e suggested mech-anisms are obtained as the temperature increases the efficiencydecreases for mixed ligands but increases for their metalcomplexes depending on the nature of bond formation be-tween the mixed ligands and aluminum surface which isdifferent from the nature of bond formation between metalcomplexes and the aluminum surface [16] Arrhenius equation(7) gives the relation between the corrosion rate andtemperature
lnRcorr lnAminusElowast
RT (7)
where A is the Arrhenius factor Elowast is the apparent activationenergy of the corrosion process R is the rate gas constant andT is the absolute temperature (e straight line slope oflogRcorr vs 1T for aluminum 1M HCl at 4times10minus4molL after7 h is minusElowast2303R for the inhibitors (Figure 12)
(e activation thermodynamic parameters for alumi-num dissolution could be obtained from the transition stateequation (8)
lnRcorr
T1113874 1113875 ln
R
Nh1113874 1113875 +
ΔSlowast
R1113888 1113889minus
ΔHlowast
RT1113888 1113889 (8)
where the entropy of activation ∆Slowast and the apparent en-thalpy of activation ∆Hlowast can be obtained from the intercept
3150
02
04
06
logR
corr
(gmiddoth
ndash1middotcm
ndash1)
08
1
12
32 325 331000T(Kndash1)
335 34 345
BlankMix ligandsZn2+
Co2+Ni2+Cu2+
Figure 12 Arrhenius of log corrosion rate (Rcorr) vs 1T for aluminum in 1M HCl without and with 004times10minus2MLminus1 of inhibitors (mixedligands and their metal complexes)
Table 9 (ermodynamic parameters for the adsorption of (004times10minus2)ML mixed ligands and their metal complexes on aluminum metalin aqueous solution of 1M HCl at different temperatures for 7 hrs
and the slope for the straight line of the relation betweenln(RcorrT) vs (1T) respectively N is Avogadrorsquos numberand h is Planckrsquos constant (e Gibbs free energy of acti-vation ∆Glowast can be detected by equation (9)
ΔGlowast ΔHlowast minusTΔSlowast (9)
Table 9 shows the thermodynamic parameters for theadsorption of mixed ligands and their metal complexes (epositive value of ∆Hlowast indicated the endothermic property ofdissolution process nature for aluminum in the acidicmedium [54]
However the blank ΔHlowast value is higher than the in-hibitor metal complexes which indicated that the inhibitionefficiency generally increases with increasing temperature(e association step is the rate-determining step rather thana dissociation process in presence of the metal complexesinhibitors due to the negative values of ΔSlowast It is known thatthe values of ΔGlowast above 40 kJmiddotmolminus1 are referred to chargetransfer from the inhibitor molecules into aluminum surfaceto form coordinated compound on the Al surface whichblocks it against corrosion process by different degrees Alsothe chemical adsorption process mechanism is confirmed bythe values of ΔGlowast above 40 kJmiddotmolminus1 [16 54ndash56]
4 Conclusions
Novel coordination materials of ternary divalent metalions (Cu(II) Ni(II) Co(II) and Zn(II)) chelated by thebidentate glutamic acid (Glu) and L-arginine (Arg) aminoacids are synthesized and characterized (e metal ionscomplexes are modelled using density DFT and TD-DFTtheory Computed molecular and spectroscopic (IR UV-Vis and EPR) properties validated the experimental re-sults (e used computational methods are capable ofproviding good structural descriptions for the TM com-plexes Consistent with the experimental properties theoptimized structures of the complexes [Cu(II) Glu-Arg]and [Co(II) Glu-Arg (H2O)2] reveal that symmetry en-vironment of Cu(II) exhibits slightly distorted squareplanar shape whereas Co(II)-complex has a distortedoctahedral (where Co(II) central ion is of C4v-localsymmetry) Spectral properties of [Ni(II) Glu-Arg(H2O)2] and [ZnmiddotGlumiddotArgmiddot(H2O)2] complexes indicatethat they have similar structure as Co(II) complex All thestudied ternary metal complexes are of different anti-fungal activities ranging from moderate to weak withoutpractically noticed inhibitory effects whereas antibacte-rial activities of all studied metal complexes show sig-nificant effects
Cytotoxicity studies against (HePG2) reveal the prom-ising potentiality of Cu(II) complex as inhibitor of cancercells(e results are correlated with the computed moleculardescriptors including dipole moment polarizability ther-modynamics and reactivity properties as well as the PESmaps
(e corrosion inhibition of aluminum metal specimensin 1M HCl is efficiently achieved by mixed ligands and theirmetal complexes studied
Data Availability
(e data used to support the findings of this study areavailable from the corresponding author upon request
Conflicts of Interest
(e authors declare that they have no conflicts of interest
Supplementary Materials
(e supplementary materials consist of six figures and twotables to further clarify the structures and trends of the newlyprepared metal ternary complexes (SupplementaryMaterials)
References
[1] Z Ozturk D A Kose A Asan et al ldquoPorous metal-organicCu(II) complex of L-Arginine 2synthesis characterizationhydrogen storage properties and molecular simulation cal-culationsrdquo Hittite Journal of Science and Engineering vol 1no 1 pp 1ndash5 2014
[2] S A Lahsasni R A Ammar M F Amin et al ldquoMixed-ligandcomplex formation of Cu(II) with 12- diphenylethylenedi-amine as primary ligand and amino acids as secondary li-gandsrdquo International Journal of Electrochemical Sciencevol 7 pp 7699ndash7711 2012
[3] H Sigel B P Operschall S S Massoud B Song andR Griesser ldquoEvidence for intramolecular aromatic-ringstacking in the physiological pH range of the mono-deprotonated xanthine residue in mixed-ligand complexescontaining xanthosinate 5prime-monophosphate (XMP)rdquo DaltonTransactions vol 46 no 46 pp 5521ndash5529 2006
[4] S Udhayakumar K G Shankar S Sowndarya S VenkateshC Muralidharan and C Rose ldquol-Arginine intercedes bio-crosslinking of a collagen-chitosan 3D-hybrid scaffold fortissue engineering and regeneration in silico in vitro and invivo studiesrdquo RSC Advances vol 7 no 40 pp 25070ndash250882017
[5] P K Datta M Chandra and A K Dey ldquoTernary complexesof copper(II) nickel(II) and zinc(II) with nitrilotriacetic acidas a primary ligand and some phenolic acids as secondaryligandsrdquo Transition Metal Chemistry vol 5 no 1ndash3 1980
[6] J S Woertink L Tian D Maiti et al ldquoSpectroscopic andcomputational studies of an end-on bound superoxo-Cu(II)complex geometric and electronic factors that determine theground staterdquo Inorganic Chemistry vol 49 no 20pp 9450ndash9459 2010
[7] S Dutta S Ray K Nagarajan et al ldquoGlutamic acid analoguesused as potent anticancer a reviewrdquo Der Pharma Chemicavol 3 no 2 pp 263ndash272 2011
[8] T Sismanoglu S Pura and A Bastug ldquoBinary and ternarymetal complexes of Congo red with amino acidsrdquo Dyes andPigments vol 70 no 2 pp 136ndash142 2006
[9] R N Patel H C Pandey K B Pandeya et al ldquoMixed ligandcomplex formation of nickel(II)copper(II) and zinc(II) withsome amino acids and imidazolesrdquo Indian Journal ofChemistry-Section A Inorganic Physical +eoretical andAnalytical Chemistry vol 38 no 8 pp 850ndash853 1999
[10] L Meng and Z Lin ldquoComplexations of alkalialkaline earthmetal cations with gaseous glutamic acidrdquo Computational and+eoretical Chemistry vol 1039 pp 1ndash10 2014
16 Journal of Chemistry
[11] L D Pinto P A L Puppin V M Behring O C AlvesN A Rey and J Felcman ldquoSolution and solid state study ofcopper(II) ternary complexes containing amino acids of in-terest for brain biochemistry-2 homocysteine with aspartateglutamate or methioninerdquo Inorganica Chimica Acta vol 386pp 60ndash67 2012
[12] A Wojciechowska A Ggor and W Zierkiewicz ldquoChiraloctahedral complexes of Co(III) as catalysts for asymmetricepoxidation of chalcones under phase transfer conditionsrdquoRSC Advances vol 5 no 46 pp 36295ndash36306 2015
[13] B M Weckhuysen A A Verberckmoes L Fu andR A Schoonheydt ldquoZeolite-encapsulated copper(II) aminoacid complexes synthesis spectroscopy and catalysisrdquo Journalof Physical Chemistry vol 100 no 22 pp 9456ndash9461 1996
[14] K Y El-Baradie N A El-Wakiel and H A El-GhamryldquoSynthesis characterization and corrosion inhibition in acidmedium ofl-histidine Schiff base complexesrdquo Applied Or-ganometallic Chemistry vol 29 no 3 pp 117ndash125 2015
[15] S S R Anthony and R Susai ldquoInhibition of corrosion ofcarbon steel in well water by arginine-Zn2+ systemrdquo Journal ofElectrochemical Science and Engineering vol 2 no 2pp 91ndash104 2012
[16] E H Isamil F F AlBlewi N Soliman and M M H Khalilldquo(ermal studies and mass loss inhibition for some newmixed amino acid metal complexes with their applicationsrdquoJournal of +ermal Analysis and Calorimetry vol 125 no 1pp 289ndash300 2016
[17] F Neese ldquo(e ORCA program system 4012rdquo Wiley In-terdisciplinary Reviews Computational Molecular Sciencevol 2 no 1 pp 73ndash78 2012
[18] S Grimme S Ehrlich and L Goerigk ldquoEffect of the dampingfunction in dispersion corrected density functional theoryrdquoJournal of Computational Chemistry vol 32 no 7pp 1456ndash1465 2011
[19] S Grimme J Antony S Ehrlich and H Krieg ldquoA consistentand accurate ab initio parametrization of density functionaldispersion correction (DFT-D) for the 94 elements H-Purdquo+e Journal of Chemical Physics vol 132 no 15 article154104 2010
[20] F Weigend ldquoHartree-Fock exchange fitting basis sets for H toRnrdquo Journal of Computational Chemistry vol 29 no 2pp 167ndash175 2008
[21] F Neese F Wennmohs and A Hansen ldquoEfficient ap-proximate and parallel Hartree-Fock and hybrid DFT cal-culations A lsquochain-of-spheresrsquo algorithm for the Hartree-Fock exchangerdquo Chemical Physics vol 356 no 1ndash3pp 98ndash109 2009
[22] R Izsak and F Neese ldquoAn overlap fitted chain of spheresexchange methodrdquo Journal of Chemical Physics vol 135no 14 article 144105 2011
[23] T Petrenko S Kossmann and F Neese ldquoEfficient time-dependent density functional theory approximations forhybrid density functionals analytical gradients and paralle-lizationrdquo Journal of Chemical Physics vol 134 no 5 article054116 2011
[24] A V Marenich C J Cramer and D G Truhlar ldquoUniversalsolvation model based on solute electron density and on acontinuum model of the solvent defined by the bulk dielectricconstant and atomic surface tensionsrdquo Journal of PhysicalChemistry B vol 113 no 18 pp 6378ndash96 2009
[25] S Donovan C Stiefbold and K Sprague ldquoChapter 3Chemical properties of amino acids and identification ofunknown amino acidsrdquo in Proceedings of the 17 thWorkshopConference of the Association for Biology
Laboratory Education (ABLE) vol 17 pp 35ndash70 Bain-bridge GA USA March 1996
[26] C C Wagner J Enrique and C Claudia ldquoVibrational andmagnetic properties of a CuMg glutamate complexrdquoArgentina Acta Farm Bonaerense vol 22 no 2 pp 137ndash1422003
[27] M Arif R Sur and M Arshad ldquoStudies on the thermaldecomposition of copper (II) flouride complexes with variousamino acids in nitrogen atmosphererdquo Turkish Journal ofChemistry vol 25 pp 73ndash79 2001
[28] A Ghosh M J Tucker and R M Hochstrasser ldquoIdentifi-cation of arginine residues in peptides by 2d-IR echo spec-troscopyrdquo Journal of Physical Chemistry A vol 115 no 34pp 9731ndash9738 2011
[29] K Nakamoto Infrared Spectra of Inorganic and CoordinationCompounds Part B Wiley-Interscience New York NY USA5th edition 1997
[30] E Santi M H Torre E Kremer S B Etcheverry andE J Baran ldquoVibrational spectra of the copper(II) and nick-el(II) complexes of piroxicamrdquo Vibrational Spectroscopyvol 5 no 3 pp 285ndash293 1993
[31] H N Aliyu and A S Mohammed ldquoSynthesis spectropho-tometric and biological activity of nickel (II) and copper (II)complexes with schiff base derived from acetylacetone andhistidinerdquo Global Advanced Research Journal of Microbiologyvol 1 no 5 pp 67ndash71 2012
[32] J S Murray and P Politzer ldquo(e electrostatic potential anoverviewrdquo Wiley Interdisciplinary Reviews ComputationalMolecular Science vol 1 no 2 pp 153ndash163 2011
[33] E R Souaya M M H Khalil and E H Ismail ldquoSynthesis andcharacterization of ternary complexes of certain hydroxylacids and their biological applicationsrdquo Research Journal ofPharmaceutical Biological and Chemical Sciences vol 5 no 4pp 18ndash30 2014
[34] N N Greenwood and A Earnshaw A Review of Chemistry ofthe Elements Pergamon Press Oxford UK 1984
[35] V Reddy N Patil and S D Angadi ldquoSynthesis character-ization and antimicrobial activity of Cu(II) Co(II) and Ni(II)complexes with ON and S Donor ligandsrdquo E-Journal ofChemistry vol 5 no 3 pp 577ndash583 2008
[36] F A Cotton G Wilkinson C A Murillo et al Advances inSchiff Base Chemistry Wiley New York NY USA 6th edi-tion 1999
[37] M M H Khalil E H Ismail S A Azim and E R SouayaldquoSynthesis characterization and thermal analysis of ternarycomplexes of nitrilotriacetic acid and alanine or phenylala-nine with some transition metalsrdquo Journal of +ermalAnalysis and Calorimetry vol 101 no 1 pp 129ndash135 2010
[38] F Mabbs and D Colisson Electron Paramagnetic Resonanceof D Transition Metal Compounds Vol 102 ElsevierAmsterdam Netherlands 1992
[39] M M H Khalil E R Souaya E H Ismail et al ldquoTernarytransition metal complexes of nitrilotriacetic acid and valineor leucine synthesis and biological applicationsrdquo ChineseJournal of Inorganic Chemistry vol 29 no 9 pp 1969ndash19782013
[40] I M Weiss C Muth R Drumm and H O K Kirchnerldquo(ermal decomposition of the amino acids glycine cysteineaspartic acid asparagine glutamic acid glutamine arginineand histidinerdquo BMC Biophysics vol 11 no 1 2018
[41] A M Petrosyan V V Ghazaryan G Giester and M FleckldquoSulfamates and methanesulfonates of L-arginine and L-his-tidinerdquo Journal of Molecular Structure vol 1163 pp 114ndash1272018
Journal of Chemistry 17
[42] T Kavitha S Haider T Kamal and M Ul-Islam ldquo(ermaldecomposition of metal complex precursor as route to thesynthesis of Co3O4 nanoparticles antibacterial activity andmechanismrdquo Journal of Alloys and Compounds vol 704pp 296ndash302 2017
[43] E M M Ibrahim L H Abdel-Rahman A M Abu-DiefA Elshafaie S K Hamdan and A M Ahmed ldquo(e synthesisof CuO andNiO nanoparticles by facile thermal decompositionof metal-Schiff base complexes and an examination of theirelectric thermoelectric and magnetic Propertiesrdquo MaterialsResearch Bulletin vol 107 pp 492ndash497 2018
[44] S Farhadi M Javanmard and G Nadri ldquoCharacterization ofcobalt oxide nanoparticles prepared by the thermal de-compositionrdquo Acta Chimica Slovenica vol 63 pp 335ndash3432016
[45] E M Zayed E H Ismail G G Mohamed M M H Khaliland A B Kamel ldquoSynthesis spectroscopic and structuralcharacterization and antimicrobial studies of metal com-plexes of a new hexadentate Schiff base ligand Spectropho-tometric determination of Fe(III) in water samples using arecovery testrdquo Monatshefte fur Chemie-Chemical Monthlyvol 145 no 5 pp 755ndash765 2014
[46] V Milacic D Chen L Ronconi K R Landis-PiwowarD Fregona and Q P Dou ldquoA novel anticancer gold(III)dithiocarbamate compound inhibits the activity of a purified20S proteasome and 26S proteasome in human breast cancercell cultures and xenograftsrdquo Cancer Research vol 66 no 21pp 10478ndash10486 2006
[47] T Mosmann ldquoRapid colorimetric assay for cellular growthand survival application to proliferation and cytotoxicityassaysrdquo Journal of Immunological Methods vol 65 no 1-2pp 55ndash63 1983
[48] R L Siegel K D Miller and A Jemal ldquoCancer statistics2018rdquo CA A Cancer Journal for Clinicians vol 68 no 1pp 7ndash30 2018
[49] S Chattopadhyay S P Chakraborty D Laha et al ldquoSurface-modified cobalt oxide nanoparticles new opportunities foranti-cancer drug developmentrdquo Cancer Nanotechnol vol 3no 1-6 pp 13ndash23 2012
[50] F Zielinski V Tognetti and L Joubert ldquoCondensed de-scriptors for reactivity a methodological studyrdquo ChemicalPhysics Letters vol 527 pp 67ndash72 2012
[51] H Wang Y He Q Yan et al ldquoCorrelation between thedielectric properties and biological activities of human ex vivohepatic tissuerdquo Physics in Medicine and Biology vol 60 no 6pp 2603ndash2617 2015
[52] F Tao F Fu F You et al ldquo(e correlation between dielectricproperties and microstructure of femoral bone in rats withdifferent bone qualitiesrdquo Annals of Biomedical Engineeringvol 42 no 6 pp 1238ndash1249 2014
[53] L Gun D Ning and Z Liang ldquoEffective permittivity ofbiological tissue comparison of theoretical model and ex-perimentrdquo Mathematical Problems in Engineering vol 2017Article ID 7249672 2017
[54] E I Ating S A Umoren I I Udousoro E E Ebenso andA P Udoh ldquoLeaves extract of Ananas sativumas greencorrosion inhibitor for aluminium in hydrochloric acid so-lutionsrdquo Green Chemistry Letters and Reviews vol 3 no 2pp 61ndash68 2010
[55] E Hamed ldquoStudies of the corrosion inhibition of copper inNa2SO4 solution using polarization and electrochemicalimpedance spectroscopyrdquo Materials Chemistry and Physicsvol 121 no 1-2 pp 70ndash76 2010
[56] H Zarrok H Oudda A Zarrouk et al ldquoWeight loss mea-surement and theoretical study of new pyridazine compoundas corrosion inhibitor for C38 steel in hydrochloric acidsolutionrdquo Der Pharma Chemica vol 3 no 6 pp 576ndash5902011
18 Journal of Chemistry
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Submit your manuscripts atwwwhindawicom
Bcomplex 2v21 + v22 minus 3v1v2( 1113857
15v2 minus 27v1( 1113857 (4)
(en 10Dq 10637253 cmminus1 is compared to the value of10935 cmminus1 obtained by the first method and both valuesconfirm octahedral structure [34] (e magnetic moment ofthe nickel complex was 31 which also confirmed octahedralstructure [16]
Racah parameters for Co(II) complex is also calculatedsimilarly
Furthermore Co(II) complexes have the effectivemagnetic moment μeff 413 (is value is higher than spinonly moment for three unpaired electrons 389 due to aconsiderable orbital contribution [34 36]
(e Zn complex did not show any d-d transitions butdisplayed charge transfer bands as shown in Table 4 (eexistence of charge transfer was due to transition betweentwo different principle quantum numbers from three to fouras distorted tetrahedron being completed by two watermolecules and forms zinc octahedral complex [34ndash37]
(e longest wavelength weak peaks are observed at516 nm (ε middotM 206 Lmiddotmolminus1middotcmminus1) and 636 nm (ε middotM
179 Lmiddotmolminus1middot cmminus1) for Co(II) and Cu(II) complexes re-spectively (e use of TD-DFT at BP86 DEF2-SVP andauxiliary basis DEF2JK level in water (using SMD solvationmodel) [24] results in λmax Co 5291 nm (oscillatorstrength f 0003) and λmax Cu 6486 nm (f 00256)which are in excellent agreement with the experimentalresults
(e computed natural transition orbitals of the longestwavelength transitions in both complexes reveal the largest(greater than 82) contribution of beta HOMO-LUMOwith minor (about 108) contribution of alpha HOMO-LUMO in case of Co(II) complex and about 992 con-tribution from the beta-HOMO-LUMO in case of Cu(II)complex MOs involved in the electronic transitions aredepicted in Figure 5 which illustrate clear dxz or dyz(e)⟶ dz2 (a1) transition in the local square pyramidal(C4v) of Co(II) ion in the Co(II) complex Metaldxy(b2g)minus dx2 minusy2(b1g) transition is dominant in case oflocal square planar symmetry of the Cu(II) complex (is isapproved by low molar absorptivity experimentally ob-served in the UV-Vis spectra of both complexes andsupported by low value of the computed oscillatorstrengths of the forbidden d-d transitions which acquiresome allowness due to geometry distortion of bothcomplexes
314 ESR Spectra For elucidation of the geometry of thecopper ternary complex ESR measurement gives veryuseful information about the stereo chemistry bondingbetween copper and ligands Figure 1S shows the ESRspectrum of the copper complex with a comparativeadvantage and axial symmetry (g || (parallel) 210748g (perpendicular) 201232 (204984) (ese valuesconfirm square planar coordination in which g || gt g gt 2so the unpaired electron found in the dx2 minus y2 orbital andthe ground state is 2B1g [38] (e observed and calculated
g values are different from ge 20023 due to spin-orbitcoupling (e computed g components are not equalreflecting anisotropic effect and the value of g changes as afunction of the orientation of the molecule relative to theexternal magnetic field (is value is close to the spin onlyvalue and it is in a fair agreement with the computed electronspin only value of ge(computed) 20498 [38] Co(II) com-plex is characterized by g 21280 (e simulated EPRspectrum of Co(II) complex returns ge value of 21085
Different values of Mulliken spin density are shown inFigure 4S in such metal-chelates point to purely anisotropiccouplings (e unpaired electron is totally localized onCo(II) ion In case of Cu(II)-complex electron spin pop-ulation is more distributed with about 46 on the Cu(II)ion(is may result in the simulated significant HF couplingin the case of chelating atoms around Cu(II) ion (e datapoint to mixed copper-nitrogen and copper-oxygen bondsin agreement with the computed optimized geometry [38]
32 +ermal Analysis (ermogravimetric analysis (TGA)for the all prepared ternary metal complexes was carried outin nitrogen atmosphere (e thermal decomposition of thefour complexes displayed similar patterns as their ligands
It is well known that amino acids exist only in solid stateso their thermal decomposition has been endothermal be-tween minus72 and minus151 kJmol when heating in range between185degC and 280degC (eir thermal decomposition releasesthree gases mainly H2O less NH3 and hardly any CO2TGA gives the weight of these gases as weight loss calcu-lations which evolve in appreciable amount [39]
Also the thermal decomposition of L-arginine-dopedKDP potassium dihydrogen phosphate crystal started to loseweight with temperature from 341K to 393K releasedammonia and water molecules gases [40]
(e amino acids are totally broken within the range603ndash793K as shown in Figure 6 and Table 5 (e first stepsare weight loss of the three gases H2O NH3 and CO2 withintemperature range about sim423ndash623K (e hydrocarbonsmatter loses weight in the temperature range sim350ndash520degC(e residues for these complexes are mixture with differentratios of metal and metal oxide above temperature range643ndash793K
It is noteworthy to mention that the geometries of thestudied complexes are similar to L-arginine metal complexreported before [41] which have been confirmed by X-raycrystallographic data of single crystals
33 Nanosized Metal Oxides Characterization
331 XRD of Nano CuO and Nano Cobaltosic Oxide(Co3O4) XRD of thermal synthesized copper oxide nano-particles starting from copper glutamic arginine-mixed li-gands complex gives characteristic peaks at 2θ 326deg 356deg387deg 489deg 536deg 582deg 616deg 663deg and 681deg for the markedindices of (110) (002) (111) (202) (020) (202) (113) (022)and (113) respectively as shown in Figure 7(a) which iscomparable with the literature values (e average primaryparticle size of the copper(II) oxide nanoparticles was
8 Journal of Chemistry
TG (m
g)
80
60
40
20
DTG
(mgmiddot
min
ndash1)
000
ndash020
ndash040
ndash060
ndash080
Weight loss ndash1925mgndash24174
Weight loss ndash1745mgndash21914
Weight loss ndash1366mgndash17154
Weight loss ndash0710mgndash8916
Weight loss ndash0276mgndash3466
273 473 673 873 1073 1273Temperature (K)
(a)
273 473 673 873 1073 1273Temperature (K)
TG (m
g)
100
50
DTG
(mgmiddot
min
ndash1)
000
ndash020
ndash040
ndash060
Weight loss ndash1890mgndash14111 Weight loss ndash8641mg
ndash64514
(b)
Figure 6 Continued
Alpha HOMO Alpha LUMO
Beta HOMO Beta LUMO
(a)
Alpha HOMO Alpha LUMO
Beta HOMO Beta LUMO
(b)
Figure 5 Frontier MOs of (a) Co(II) complex and (b) Cu(II) complex involved in the longest wavelength electronic transition Surfacessimilar to that of Co complex are obtained in case of Ni (ere are no d-d transitions in Zn complexes
Journal of Chemistry 9
Table 5 (ermogravimetric analysis decomposition data for the metal ternary complexes
Complexes Mol (wt) TG range (degC) Mass loss () found (calculated) Total mass loss () Assignment
Figure 6 TG and DTG of (a) [Co(glu)(arg)(H2O)2]middot05H2O (b) [Ni(glu)(arg)(H2O)2]middot05H2O (c) [Cu(glu)((arg)]middotH2O and(d) [ZnmiddotGlumiddotArgmiddot(H2O)2]middotH2O
10 Journal of Chemistry
estimated using well-known DebyendashScherrer formula usingthe full width at half maximum (FWHM) of the (111) peaksin the XRD K(α) is the wavelength of X-ray source(15406 A 015406 nm) β∆θ is the full width at halfmaximum (FWHM 01378) and θ 387 is the diffractionangle corresponding to the lattice plane (111) which gives Dsim143ndash204plusmn 08 nm patterns [42ndash44]
(e pattern of XRD for cobalt oxide nanoparticles showscharacteristic peaks at 2θ values at 1898deg 3127deg 3682deg3848deg 4478deg 5568deg 5934deg 6521deg and 7731deg which arecorresponding to their indices (111) (220) (311) (400) (511)and (440) in agreement with JCPDS Card No 76ndash1802 (ispattern confirms the phase formation of cobalt oxidenanoparticle Figure 7(b) (e average size of the Co3O4particles was calculated by the DebyendashScherrer equationDK(α) λ(β cos θ) whereD is the average crystalline size λ isthe wavelength of CuKα θ is Braggrsquos angle and β is the fullwidth at half maximum (FWHM) of the diffraction peak (eaverage dimension D is sim147ndash182plusmn 06 nm at 2θ 3682degwhich is the intense peak [44]
332 EDX of Nano CuO (e synthesized nano copperoxide is confirmed by the EDX spectrum and SEM imagemeasurement shown in Figure 8 which confirms the highestformation percent of CuO and traces of copper carbide (eSEM image for nano copper oxide CuO shows a mixingnanosize 270sim1079 nm [42 43]
333 EDX of Nano Cobaltosic Oxide (e synthesized nanocobalt oxide is confirmed by the EDX spectrum measure-ment shown in Figure 9 which confirms the highest for-mation percent of cobaltosic oxide Co3O4 and traces ofcobalt carbide (e SEM image for nano cobaltosic oxideCo3O4 shows a mixing nanosize 318ndash8543 nm
34 Applications
341 Biological Activity Mixed ligand ternary complexeshave been examined for their in vitro antimicrobial activity(is investigation was performed using the diffusion agartechnique (Figure 5S) (e assays collection included
g-negative (Pseudomonas aeruginosa RCMB 010043 andEscherichia coli RCMB 010052) pathogenic bacteria usingGentamicin 5mgml as a reference compound and g-pos-itive (Streptococcus pneumoniae RCMB 010010 and Bacillissubtilis RCMB 010067) pathogenic bacteria using Ampi-cillin 5mgml as a reference compound It was also in-cluded four fungi (Aspergillus fumigatus RCMB 02568Syncephalastrum racemosum RCMB 05922 Geotrichumcandidum RCMB 05097 and Candida albicans RCMB05036) using Amphotericin B 5mgml as a referencecompound [30 45]
(e inhibitory effects of the used ligands and theirternary polymer complexes against the used organisms aregiven in Table 6 In general the used ligands did not displayantifungal or antibacterial inhibitory
For antifungal assay examination and based on theminimum inhibitory concentration (MIC) values it is foundthat the inhibitory effect of all the ternary complexes varyfrom moderate to weak against Amphotericin B controlexcept in the case of Candida albicans (RCMB 05036) whichis not affected by both cobalt and zinc complexes
(e antibacterial activities of the obtained ternarycomplexes are determined in terms of MIC values As shownin Table 6 all complexes display moderate activities againstStreptococcus pneumonia (RCMB 010010) and Bacillis sub-tilis RCMB 010067 (e growth of the gram-negative bac-teria Pseudomonas aeruginosa RCMB 010043 andEscherichia coli RCMB 010052 is extremely affected by bothcopper and nickel complexes which display strong inhibitionagainst the gram-negative pathogenic bacteria with MICvalue less than the Gentamicin control (e remainingcomplexes do not display the same behavior during theassay
342 Cytotoxicity One of the fundamental goals in me-dicinal chemistry is the development of new anticancer andantimicrobial therapeutic agents Cancer treatment usingmetal-based drugs is one of the very effective strategies as themetal ions are capable of binding to nucleic acids stereo-specifically with varying strength
In vitro anticancer activity evaluation of the newlysynthesized compounds was carried out against human
Cou
nts
400
300
200
100
010 20 30 40
Angles (deg2θ)50 60 70
(a)
Cou
nts
100
50
010 20 30 40
Angles (deg2θ)50 60 70
(b)
Figure 7 XRD pattern of (a) copper oxide CuO and (b) cobalt oxide Co3O4 prepared by thermal decomposition at 550Cdeg starting frommetal glutamic arginine mixed ligands complex
Journal of Chemistry 11
cancer cell lines hepatocellular carcinoma (HePG2) becauseliver cancer is the third most common cause of death incancer using MTT method [26 46 47]
Doxorubicin HCl is one of the most effective anti-cancer agents is used as a reference drug in this study (eobtained results from Table 2S indicated that most of thesemoleculesrsquo behavior can be observed from the values of the
half maximal inhibitory concentration IC50 whichfor glutamic and arginine are 167 and 376 μgmlrespectively
IC50 results indicate that the ternary complexes havepromised inhibition of HePG2 liver tumors [48 49]
Cell viability was assessed by themitochondrial-dependentreduction of yellow MTT (3-(45-dimethylthiazol-2-yl)-25-
108K096K084K072K060K048K036K024K012K000K
000 100 200 300 400 500 600 700 800 900
Cu Kβ
Cu Kα
Cu L
O KC K
(a) (b)
Figure 8 EDX and SEM images of CuO obtained by thermal decomposition at 550Cdeg starting from copper glutamic arginine mixed ligandscomplex
135K120K105K090K075K060K045K030K015K000K
000 100 200 300 400 500 600 700 800 900
O K
Co L Co Kα
Co Kβ
(a) (b)
Figure 9 EDX and SEM images of Co3O4 obtained by thermal decomposition at 550Cdeg starting from cobalt glutamic arginine mixedligands complex
Table 6 Antimicrobial activity of prepared ternary metal complexes
Sample tested microorganisms Glutamicacid L-arginine (1) (2) (3) (4) Standard
lowastNA no activity Values in bracket are the MIC values
12 Journal of Chemistry
diphenyl tetrazolium bromide) to insoluble purple formazan[45] (e prepared ternary metal complexes are of differentviability percentages as depicted in Figure 10 Data of bothligands are also included for comparison
Table 2S shows that the ligands have lower inhibition ofHePG2 than their metal ternary complexes (e coppercomplex introduces the highest inhibition
Additionally Table 7 summarizes some computedelectrical reactivity [50] and thermodynamic propertiesfor Co(II) and Cu(II) complexes (as maximum andminimum IC50 of the four prepared ternary metalscomplexes) which are correlated with the inhibition ofhuman cancer cells and are useful to explain the roleplayed by molecular properties in inhibition of humancancer cells
(e simulated data summarized in Table 7 conclude thefollowing
(i) Cu complex is more energetically stable relative toCo complex by about minus265 kJmol
(ii) Cu complex is characterized by lower dipole mo-ment and lower polarizability relative to Co(II)complexes
(iii) Enthalpy and Gibbs free energy of the Cu complexesare more stable by about minus265 kJmol relative toCo(II) complex Lower entropy reflects lower degreeof randomness of Cu(II) complex
(iv) (e chemical potential (μprime) (negative of molecularelectronegativity) of Cu(II) complex is much higherthan that of Co(II) complex reflecting the enhancedreactivity of Cu(II) complex as nucleophile becauseμprime measures the escaping tendency of electrons fromthe complex (μprime (LUMO+HOMO)2) [50]
(v) Cu complex is characterized by lower hardness thanCo(II) complex Hardness measures the resistanceto electron transfer (η (LUMO-HOMO)2) [50]
It seems that more thermodynamically stable and lesspolar Cu complex exhibits that enhanced responsive elec-tron cloud transfer to the surrounding tumor relative to theCo(II) complex (ese quantitative molecular descriptors[50] explain the promising inhibition activity of the Cu(II)complex (e results are correlated with the above-discussedPES results which show that Cu complex could act asnucleophile whereas Co complex is of enhanced electro-philic nature
(e nucleophilicity of Cu complex (seeking for positivelycharged sites of the reactant) together with its electricalthermodynamic and molecular properties favors its prom-ising inhibition activity towards HePG2 cancer cell [51ndash53]
343 Corrosion Inhibition of Aluminum An assessment ofcorrosion rates and inhibition efficiency for aluminum withdifferent inhibitor concentrations were computed as followscorrosion rate Rcorr was computed using equation (5)
Rcorr M1 minusM2( 1113857(mg)
A cm2( ) times t(h) (5)
where M1 weight (g) before immersion M2 weight (g)after immersion A area (cm2) of the specimen andt exposure time (h)
(e inhibition efficiency (IE) was evaluated usingequation (6)
IE Rblank minusRinh
Rblank1113890 1113891 times 100 (6)
120
60
100
80
60
40
20
00 10 20 30 40 50
GlutamicLarginineCu(II)
Ni(II)Co(II)Zn(II)
Figure 10 Cell viability of (HePG2) at different concentrations of ligands and the prepared metal complexes
Table 7 Simulated electrical properties of complexes studied exhibiting enhanced inhibition of HePG2
where Rblank corrosion rates in the absence of inhibitor andRinh corrosion rates in the presence of inhibitor [16]
Table 8 shows the calculated corrosion rates and inhibitionefficiencies of aluminum specimens in aqueous solution of 1MHCl as the corrosive medium in absence and presence ofmixed ligands and their ternary metal complexes at differenttemperatures (293 ndash313) K for 7 hours of each concentrationFigure 6S shows that as the concentration of ligands and theircomplexes increases Rcorr decreases and IE increases formixed ligands and their metal complexes acted as more ef-ficient inhibitors than their mixed ligands alone
344 Adsorption Isotherms and the +ermodynamic Acti-vation Parameters (e metal surface coverage degree(θIE100) was subjected to different adsorption iso-therms (e well fit for weight loss data is obtained forLangmuir adsorption isotherm Figure 11
Table 8 Corrosion parameters for aluminum in aqueous solution of 1M HCl in the absence and presence of different concentrations ofmixed ligands and their metal complexes at different temperatures for 7 hrs
Inhibitors C (times10minus2M)Corrosion rate times10minus4
Figure 11 Langmuir adsorption isotherms of the mixed ligands(L) and their metal complexes
14 Journal of Chemistry
(e temperature effect (293ndash313 K) on aluminum weightloss inhibition may be attributed to two main mechanismsphysical and chemical adsorption [37] (e suggested mech-anisms are obtained as the temperature increases the efficiencydecreases for mixed ligands but increases for their metalcomplexes depending on the nature of bond formation be-tween the mixed ligands and aluminum surface which isdifferent from the nature of bond formation between metalcomplexes and the aluminum surface [16] Arrhenius equation(7) gives the relation between the corrosion rate andtemperature
lnRcorr lnAminusElowast
RT (7)
where A is the Arrhenius factor Elowast is the apparent activationenergy of the corrosion process R is the rate gas constant andT is the absolute temperature (e straight line slope oflogRcorr vs 1T for aluminum 1M HCl at 4times10minus4molL after7 h is minusElowast2303R for the inhibitors (Figure 12)
(e activation thermodynamic parameters for alumi-num dissolution could be obtained from the transition stateequation (8)
lnRcorr
T1113874 1113875 ln
R
Nh1113874 1113875 +
ΔSlowast
R1113888 1113889minus
ΔHlowast
RT1113888 1113889 (8)
where the entropy of activation ∆Slowast and the apparent en-thalpy of activation ∆Hlowast can be obtained from the intercept
3150
02
04
06
logR
corr
(gmiddoth
ndash1middotcm
ndash1)
08
1
12
32 325 331000T(Kndash1)
335 34 345
BlankMix ligandsZn2+
Co2+Ni2+Cu2+
Figure 12 Arrhenius of log corrosion rate (Rcorr) vs 1T for aluminum in 1M HCl without and with 004times10minus2MLminus1 of inhibitors (mixedligands and their metal complexes)
Table 9 (ermodynamic parameters for the adsorption of (004times10minus2)ML mixed ligands and their metal complexes on aluminum metalin aqueous solution of 1M HCl at different temperatures for 7 hrs
and the slope for the straight line of the relation betweenln(RcorrT) vs (1T) respectively N is Avogadrorsquos numberand h is Planckrsquos constant (e Gibbs free energy of acti-vation ∆Glowast can be detected by equation (9)
ΔGlowast ΔHlowast minusTΔSlowast (9)
Table 9 shows the thermodynamic parameters for theadsorption of mixed ligands and their metal complexes (epositive value of ∆Hlowast indicated the endothermic property ofdissolution process nature for aluminum in the acidicmedium [54]
However the blank ΔHlowast value is higher than the in-hibitor metal complexes which indicated that the inhibitionefficiency generally increases with increasing temperature(e association step is the rate-determining step rather thana dissociation process in presence of the metal complexesinhibitors due to the negative values of ΔSlowast It is known thatthe values of ΔGlowast above 40 kJmiddotmolminus1 are referred to chargetransfer from the inhibitor molecules into aluminum surfaceto form coordinated compound on the Al surface whichblocks it against corrosion process by different degrees Alsothe chemical adsorption process mechanism is confirmed bythe values of ΔGlowast above 40 kJmiddotmolminus1 [16 54ndash56]
4 Conclusions
Novel coordination materials of ternary divalent metalions (Cu(II) Ni(II) Co(II) and Zn(II)) chelated by thebidentate glutamic acid (Glu) and L-arginine (Arg) aminoacids are synthesized and characterized (e metal ionscomplexes are modelled using density DFT and TD-DFTtheory Computed molecular and spectroscopic (IR UV-Vis and EPR) properties validated the experimental re-sults (e used computational methods are capable ofproviding good structural descriptions for the TM com-plexes Consistent with the experimental properties theoptimized structures of the complexes [Cu(II) Glu-Arg]and [Co(II) Glu-Arg (H2O)2] reveal that symmetry en-vironment of Cu(II) exhibits slightly distorted squareplanar shape whereas Co(II)-complex has a distortedoctahedral (where Co(II) central ion is of C4v-localsymmetry) Spectral properties of [Ni(II) Glu-Arg(H2O)2] and [ZnmiddotGlumiddotArgmiddot(H2O)2] complexes indicatethat they have similar structure as Co(II) complex All thestudied ternary metal complexes are of different anti-fungal activities ranging from moderate to weak withoutpractically noticed inhibitory effects whereas antibacte-rial activities of all studied metal complexes show sig-nificant effects
Cytotoxicity studies against (HePG2) reveal the prom-ising potentiality of Cu(II) complex as inhibitor of cancercells(e results are correlated with the computed moleculardescriptors including dipole moment polarizability ther-modynamics and reactivity properties as well as the PESmaps
(e corrosion inhibition of aluminum metal specimensin 1M HCl is efficiently achieved by mixed ligands and theirmetal complexes studied
Data Availability
(e data used to support the findings of this study areavailable from the corresponding author upon request
Conflicts of Interest
(e authors declare that they have no conflicts of interest
Supplementary Materials
(e supplementary materials consist of six figures and twotables to further clarify the structures and trends of the newlyprepared metal ternary complexes (SupplementaryMaterials)
References
[1] Z Ozturk D A Kose A Asan et al ldquoPorous metal-organicCu(II) complex of L-Arginine 2synthesis characterizationhydrogen storage properties and molecular simulation cal-culationsrdquo Hittite Journal of Science and Engineering vol 1no 1 pp 1ndash5 2014
[2] S A Lahsasni R A Ammar M F Amin et al ldquoMixed-ligandcomplex formation of Cu(II) with 12- diphenylethylenedi-amine as primary ligand and amino acids as secondary li-gandsrdquo International Journal of Electrochemical Sciencevol 7 pp 7699ndash7711 2012
[3] H Sigel B P Operschall S S Massoud B Song andR Griesser ldquoEvidence for intramolecular aromatic-ringstacking in the physiological pH range of the mono-deprotonated xanthine residue in mixed-ligand complexescontaining xanthosinate 5prime-monophosphate (XMP)rdquo DaltonTransactions vol 46 no 46 pp 5521ndash5529 2006
[4] S Udhayakumar K G Shankar S Sowndarya S VenkateshC Muralidharan and C Rose ldquol-Arginine intercedes bio-crosslinking of a collagen-chitosan 3D-hybrid scaffold fortissue engineering and regeneration in silico in vitro and invivo studiesrdquo RSC Advances vol 7 no 40 pp 25070ndash250882017
[5] P K Datta M Chandra and A K Dey ldquoTernary complexesof copper(II) nickel(II) and zinc(II) with nitrilotriacetic acidas a primary ligand and some phenolic acids as secondaryligandsrdquo Transition Metal Chemistry vol 5 no 1ndash3 1980
[6] J S Woertink L Tian D Maiti et al ldquoSpectroscopic andcomputational studies of an end-on bound superoxo-Cu(II)complex geometric and electronic factors that determine theground staterdquo Inorganic Chemistry vol 49 no 20pp 9450ndash9459 2010
[7] S Dutta S Ray K Nagarajan et al ldquoGlutamic acid analoguesused as potent anticancer a reviewrdquo Der Pharma Chemicavol 3 no 2 pp 263ndash272 2011
[8] T Sismanoglu S Pura and A Bastug ldquoBinary and ternarymetal complexes of Congo red with amino acidsrdquo Dyes andPigments vol 70 no 2 pp 136ndash142 2006
[9] R N Patel H C Pandey K B Pandeya et al ldquoMixed ligandcomplex formation of nickel(II)copper(II) and zinc(II) withsome amino acids and imidazolesrdquo Indian Journal ofChemistry-Section A Inorganic Physical +eoretical andAnalytical Chemistry vol 38 no 8 pp 850ndash853 1999
[10] L Meng and Z Lin ldquoComplexations of alkalialkaline earthmetal cations with gaseous glutamic acidrdquo Computational and+eoretical Chemistry vol 1039 pp 1ndash10 2014
16 Journal of Chemistry
[11] L D Pinto P A L Puppin V M Behring O C AlvesN A Rey and J Felcman ldquoSolution and solid state study ofcopper(II) ternary complexes containing amino acids of in-terest for brain biochemistry-2 homocysteine with aspartateglutamate or methioninerdquo Inorganica Chimica Acta vol 386pp 60ndash67 2012
[12] A Wojciechowska A Ggor and W Zierkiewicz ldquoChiraloctahedral complexes of Co(III) as catalysts for asymmetricepoxidation of chalcones under phase transfer conditionsrdquoRSC Advances vol 5 no 46 pp 36295ndash36306 2015
[13] B M Weckhuysen A A Verberckmoes L Fu andR A Schoonheydt ldquoZeolite-encapsulated copper(II) aminoacid complexes synthesis spectroscopy and catalysisrdquo Journalof Physical Chemistry vol 100 no 22 pp 9456ndash9461 1996
[14] K Y El-Baradie N A El-Wakiel and H A El-GhamryldquoSynthesis characterization and corrosion inhibition in acidmedium ofl-histidine Schiff base complexesrdquo Applied Or-ganometallic Chemistry vol 29 no 3 pp 117ndash125 2015
[15] S S R Anthony and R Susai ldquoInhibition of corrosion ofcarbon steel in well water by arginine-Zn2+ systemrdquo Journal ofElectrochemical Science and Engineering vol 2 no 2pp 91ndash104 2012
[16] E H Isamil F F AlBlewi N Soliman and M M H Khalilldquo(ermal studies and mass loss inhibition for some newmixed amino acid metal complexes with their applicationsrdquoJournal of +ermal Analysis and Calorimetry vol 125 no 1pp 289ndash300 2016
[17] F Neese ldquo(e ORCA program system 4012rdquo Wiley In-terdisciplinary Reviews Computational Molecular Sciencevol 2 no 1 pp 73ndash78 2012
[18] S Grimme S Ehrlich and L Goerigk ldquoEffect of the dampingfunction in dispersion corrected density functional theoryrdquoJournal of Computational Chemistry vol 32 no 7pp 1456ndash1465 2011
[19] S Grimme J Antony S Ehrlich and H Krieg ldquoA consistentand accurate ab initio parametrization of density functionaldispersion correction (DFT-D) for the 94 elements H-Purdquo+e Journal of Chemical Physics vol 132 no 15 article154104 2010
[20] F Weigend ldquoHartree-Fock exchange fitting basis sets for H toRnrdquo Journal of Computational Chemistry vol 29 no 2pp 167ndash175 2008
[21] F Neese F Wennmohs and A Hansen ldquoEfficient ap-proximate and parallel Hartree-Fock and hybrid DFT cal-culations A lsquochain-of-spheresrsquo algorithm for the Hartree-Fock exchangerdquo Chemical Physics vol 356 no 1ndash3pp 98ndash109 2009
[22] R Izsak and F Neese ldquoAn overlap fitted chain of spheresexchange methodrdquo Journal of Chemical Physics vol 135no 14 article 144105 2011
[23] T Petrenko S Kossmann and F Neese ldquoEfficient time-dependent density functional theory approximations forhybrid density functionals analytical gradients and paralle-lizationrdquo Journal of Chemical Physics vol 134 no 5 article054116 2011
[24] A V Marenich C J Cramer and D G Truhlar ldquoUniversalsolvation model based on solute electron density and on acontinuum model of the solvent defined by the bulk dielectricconstant and atomic surface tensionsrdquo Journal of PhysicalChemistry B vol 113 no 18 pp 6378ndash96 2009
[25] S Donovan C Stiefbold and K Sprague ldquoChapter 3Chemical properties of amino acids and identification ofunknown amino acidsrdquo in Proceedings of the 17 thWorkshopConference of the Association for Biology
Laboratory Education (ABLE) vol 17 pp 35ndash70 Bain-bridge GA USA March 1996
[26] C C Wagner J Enrique and C Claudia ldquoVibrational andmagnetic properties of a CuMg glutamate complexrdquoArgentina Acta Farm Bonaerense vol 22 no 2 pp 137ndash1422003
[27] M Arif R Sur and M Arshad ldquoStudies on the thermaldecomposition of copper (II) flouride complexes with variousamino acids in nitrogen atmosphererdquo Turkish Journal ofChemistry vol 25 pp 73ndash79 2001
[28] A Ghosh M J Tucker and R M Hochstrasser ldquoIdentifi-cation of arginine residues in peptides by 2d-IR echo spec-troscopyrdquo Journal of Physical Chemistry A vol 115 no 34pp 9731ndash9738 2011
[29] K Nakamoto Infrared Spectra of Inorganic and CoordinationCompounds Part B Wiley-Interscience New York NY USA5th edition 1997
[30] E Santi M H Torre E Kremer S B Etcheverry andE J Baran ldquoVibrational spectra of the copper(II) and nick-el(II) complexes of piroxicamrdquo Vibrational Spectroscopyvol 5 no 3 pp 285ndash293 1993
[31] H N Aliyu and A S Mohammed ldquoSynthesis spectropho-tometric and biological activity of nickel (II) and copper (II)complexes with schiff base derived from acetylacetone andhistidinerdquo Global Advanced Research Journal of Microbiologyvol 1 no 5 pp 67ndash71 2012
[32] J S Murray and P Politzer ldquo(e electrostatic potential anoverviewrdquo Wiley Interdisciplinary Reviews ComputationalMolecular Science vol 1 no 2 pp 153ndash163 2011
[33] E R Souaya M M H Khalil and E H Ismail ldquoSynthesis andcharacterization of ternary complexes of certain hydroxylacids and their biological applicationsrdquo Research Journal ofPharmaceutical Biological and Chemical Sciences vol 5 no 4pp 18ndash30 2014
[34] N N Greenwood and A Earnshaw A Review of Chemistry ofthe Elements Pergamon Press Oxford UK 1984
[35] V Reddy N Patil and S D Angadi ldquoSynthesis character-ization and antimicrobial activity of Cu(II) Co(II) and Ni(II)complexes with ON and S Donor ligandsrdquo E-Journal ofChemistry vol 5 no 3 pp 577ndash583 2008
[36] F A Cotton G Wilkinson C A Murillo et al Advances inSchiff Base Chemistry Wiley New York NY USA 6th edi-tion 1999
[37] M M H Khalil E H Ismail S A Azim and E R SouayaldquoSynthesis characterization and thermal analysis of ternarycomplexes of nitrilotriacetic acid and alanine or phenylala-nine with some transition metalsrdquo Journal of +ermalAnalysis and Calorimetry vol 101 no 1 pp 129ndash135 2010
[38] F Mabbs and D Colisson Electron Paramagnetic Resonanceof D Transition Metal Compounds Vol 102 ElsevierAmsterdam Netherlands 1992
[39] M M H Khalil E R Souaya E H Ismail et al ldquoTernarytransition metal complexes of nitrilotriacetic acid and valineor leucine synthesis and biological applicationsrdquo ChineseJournal of Inorganic Chemistry vol 29 no 9 pp 1969ndash19782013
[40] I M Weiss C Muth R Drumm and H O K Kirchnerldquo(ermal decomposition of the amino acids glycine cysteineaspartic acid asparagine glutamic acid glutamine arginineand histidinerdquo BMC Biophysics vol 11 no 1 2018
[41] A M Petrosyan V V Ghazaryan G Giester and M FleckldquoSulfamates and methanesulfonates of L-arginine and L-his-tidinerdquo Journal of Molecular Structure vol 1163 pp 114ndash1272018
Journal of Chemistry 17
[42] T Kavitha S Haider T Kamal and M Ul-Islam ldquo(ermaldecomposition of metal complex precursor as route to thesynthesis of Co3O4 nanoparticles antibacterial activity andmechanismrdquo Journal of Alloys and Compounds vol 704pp 296ndash302 2017
[43] E M M Ibrahim L H Abdel-Rahman A M Abu-DiefA Elshafaie S K Hamdan and A M Ahmed ldquo(e synthesisof CuO andNiO nanoparticles by facile thermal decompositionof metal-Schiff base complexes and an examination of theirelectric thermoelectric and magnetic Propertiesrdquo MaterialsResearch Bulletin vol 107 pp 492ndash497 2018
[44] S Farhadi M Javanmard and G Nadri ldquoCharacterization ofcobalt oxide nanoparticles prepared by the thermal de-compositionrdquo Acta Chimica Slovenica vol 63 pp 335ndash3432016
[45] E M Zayed E H Ismail G G Mohamed M M H Khaliland A B Kamel ldquoSynthesis spectroscopic and structuralcharacterization and antimicrobial studies of metal com-plexes of a new hexadentate Schiff base ligand Spectropho-tometric determination of Fe(III) in water samples using arecovery testrdquo Monatshefte fur Chemie-Chemical Monthlyvol 145 no 5 pp 755ndash765 2014
[46] V Milacic D Chen L Ronconi K R Landis-PiwowarD Fregona and Q P Dou ldquoA novel anticancer gold(III)dithiocarbamate compound inhibits the activity of a purified20S proteasome and 26S proteasome in human breast cancercell cultures and xenograftsrdquo Cancer Research vol 66 no 21pp 10478ndash10486 2006
[47] T Mosmann ldquoRapid colorimetric assay for cellular growthand survival application to proliferation and cytotoxicityassaysrdquo Journal of Immunological Methods vol 65 no 1-2pp 55ndash63 1983
[48] R L Siegel K D Miller and A Jemal ldquoCancer statistics2018rdquo CA A Cancer Journal for Clinicians vol 68 no 1pp 7ndash30 2018
[49] S Chattopadhyay S P Chakraborty D Laha et al ldquoSurface-modified cobalt oxide nanoparticles new opportunities foranti-cancer drug developmentrdquo Cancer Nanotechnol vol 3no 1-6 pp 13ndash23 2012
[50] F Zielinski V Tognetti and L Joubert ldquoCondensed de-scriptors for reactivity a methodological studyrdquo ChemicalPhysics Letters vol 527 pp 67ndash72 2012
[51] H Wang Y He Q Yan et al ldquoCorrelation between thedielectric properties and biological activities of human ex vivohepatic tissuerdquo Physics in Medicine and Biology vol 60 no 6pp 2603ndash2617 2015
[52] F Tao F Fu F You et al ldquo(e correlation between dielectricproperties and microstructure of femoral bone in rats withdifferent bone qualitiesrdquo Annals of Biomedical Engineeringvol 42 no 6 pp 1238ndash1249 2014
[53] L Gun D Ning and Z Liang ldquoEffective permittivity ofbiological tissue comparison of theoretical model and ex-perimentrdquo Mathematical Problems in Engineering vol 2017Article ID 7249672 2017
[54] E I Ating S A Umoren I I Udousoro E E Ebenso andA P Udoh ldquoLeaves extract of Ananas sativumas greencorrosion inhibitor for aluminium in hydrochloric acid so-lutionsrdquo Green Chemistry Letters and Reviews vol 3 no 2pp 61ndash68 2010
[55] E Hamed ldquoStudies of the corrosion inhibition of copper inNa2SO4 solution using polarization and electrochemicalimpedance spectroscopyrdquo Materials Chemistry and Physicsvol 121 no 1-2 pp 70ndash76 2010
[56] H Zarrok H Oudda A Zarrouk et al ldquoWeight loss mea-surement and theoretical study of new pyridazine compoundas corrosion inhibitor for C38 steel in hydrochloric acidsolutionrdquo Der Pharma Chemica vol 3 no 6 pp 576ndash5902011
18 Journal of Chemistry
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Submit your manuscripts atwwwhindawicom
TG (m
g)
80
60
40
20
DTG
(mgmiddot
min
ndash1)
000
ndash020
ndash040
ndash060
ndash080
Weight loss ndash1925mgndash24174
Weight loss ndash1745mgndash21914
Weight loss ndash1366mgndash17154
Weight loss ndash0710mgndash8916
Weight loss ndash0276mgndash3466
273 473 673 873 1073 1273Temperature (K)
(a)
273 473 673 873 1073 1273Temperature (K)
TG (m
g)
100
50
DTG
(mgmiddot
min
ndash1)
000
ndash020
ndash040
ndash060
Weight loss ndash1890mgndash14111 Weight loss ndash8641mg
ndash64514
(b)
Figure 6 Continued
Alpha HOMO Alpha LUMO
Beta HOMO Beta LUMO
(a)
Alpha HOMO Alpha LUMO
Beta HOMO Beta LUMO
(b)
Figure 5 Frontier MOs of (a) Co(II) complex and (b) Cu(II) complex involved in the longest wavelength electronic transition Surfacessimilar to that of Co complex are obtained in case of Ni (ere are no d-d transitions in Zn complexes
Journal of Chemistry 9
Table 5 (ermogravimetric analysis decomposition data for the metal ternary complexes
Complexes Mol (wt) TG range (degC) Mass loss () found (calculated) Total mass loss () Assignment
Figure 6 TG and DTG of (a) [Co(glu)(arg)(H2O)2]middot05H2O (b) [Ni(glu)(arg)(H2O)2]middot05H2O (c) [Cu(glu)((arg)]middotH2O and(d) [ZnmiddotGlumiddotArgmiddot(H2O)2]middotH2O
10 Journal of Chemistry
estimated using well-known DebyendashScherrer formula usingthe full width at half maximum (FWHM) of the (111) peaksin the XRD K(α) is the wavelength of X-ray source(15406 A 015406 nm) β∆θ is the full width at halfmaximum (FWHM 01378) and θ 387 is the diffractionangle corresponding to the lattice plane (111) which gives Dsim143ndash204plusmn 08 nm patterns [42ndash44]
(e pattern of XRD for cobalt oxide nanoparticles showscharacteristic peaks at 2θ values at 1898deg 3127deg 3682deg3848deg 4478deg 5568deg 5934deg 6521deg and 7731deg which arecorresponding to their indices (111) (220) (311) (400) (511)and (440) in agreement with JCPDS Card No 76ndash1802 (ispattern confirms the phase formation of cobalt oxidenanoparticle Figure 7(b) (e average size of the Co3O4particles was calculated by the DebyendashScherrer equationDK(α) λ(β cos θ) whereD is the average crystalline size λ isthe wavelength of CuKα θ is Braggrsquos angle and β is the fullwidth at half maximum (FWHM) of the diffraction peak (eaverage dimension D is sim147ndash182plusmn 06 nm at 2θ 3682degwhich is the intense peak [44]
332 EDX of Nano CuO (e synthesized nano copperoxide is confirmed by the EDX spectrum and SEM imagemeasurement shown in Figure 8 which confirms the highestformation percent of CuO and traces of copper carbide (eSEM image for nano copper oxide CuO shows a mixingnanosize 270sim1079 nm [42 43]
333 EDX of Nano Cobaltosic Oxide (e synthesized nanocobalt oxide is confirmed by the EDX spectrum measure-ment shown in Figure 9 which confirms the highest for-mation percent of cobaltosic oxide Co3O4 and traces ofcobalt carbide (e SEM image for nano cobaltosic oxideCo3O4 shows a mixing nanosize 318ndash8543 nm
34 Applications
341 Biological Activity Mixed ligand ternary complexeshave been examined for their in vitro antimicrobial activity(is investigation was performed using the diffusion agartechnique (Figure 5S) (e assays collection included
g-negative (Pseudomonas aeruginosa RCMB 010043 andEscherichia coli RCMB 010052) pathogenic bacteria usingGentamicin 5mgml as a reference compound and g-pos-itive (Streptococcus pneumoniae RCMB 010010 and Bacillissubtilis RCMB 010067) pathogenic bacteria using Ampi-cillin 5mgml as a reference compound It was also in-cluded four fungi (Aspergillus fumigatus RCMB 02568Syncephalastrum racemosum RCMB 05922 Geotrichumcandidum RCMB 05097 and Candida albicans RCMB05036) using Amphotericin B 5mgml as a referencecompound [30 45]
(e inhibitory effects of the used ligands and theirternary polymer complexes against the used organisms aregiven in Table 6 In general the used ligands did not displayantifungal or antibacterial inhibitory
For antifungal assay examination and based on theminimum inhibitory concentration (MIC) values it is foundthat the inhibitory effect of all the ternary complexes varyfrom moderate to weak against Amphotericin B controlexcept in the case of Candida albicans (RCMB 05036) whichis not affected by both cobalt and zinc complexes
(e antibacterial activities of the obtained ternarycomplexes are determined in terms of MIC values As shownin Table 6 all complexes display moderate activities againstStreptococcus pneumonia (RCMB 010010) and Bacillis sub-tilis RCMB 010067 (e growth of the gram-negative bac-teria Pseudomonas aeruginosa RCMB 010043 andEscherichia coli RCMB 010052 is extremely affected by bothcopper and nickel complexes which display strong inhibitionagainst the gram-negative pathogenic bacteria with MICvalue less than the Gentamicin control (e remainingcomplexes do not display the same behavior during theassay
342 Cytotoxicity One of the fundamental goals in me-dicinal chemistry is the development of new anticancer andantimicrobial therapeutic agents Cancer treatment usingmetal-based drugs is one of the very effective strategies as themetal ions are capable of binding to nucleic acids stereo-specifically with varying strength
In vitro anticancer activity evaluation of the newlysynthesized compounds was carried out against human
Cou
nts
400
300
200
100
010 20 30 40
Angles (deg2θ)50 60 70
(a)
Cou
nts
100
50
010 20 30 40
Angles (deg2θ)50 60 70
(b)
Figure 7 XRD pattern of (a) copper oxide CuO and (b) cobalt oxide Co3O4 prepared by thermal decomposition at 550Cdeg starting frommetal glutamic arginine mixed ligands complex
Journal of Chemistry 11
cancer cell lines hepatocellular carcinoma (HePG2) becauseliver cancer is the third most common cause of death incancer using MTT method [26 46 47]
Doxorubicin HCl is one of the most effective anti-cancer agents is used as a reference drug in this study (eobtained results from Table 2S indicated that most of thesemoleculesrsquo behavior can be observed from the values of the
half maximal inhibitory concentration IC50 whichfor glutamic and arginine are 167 and 376 μgmlrespectively
IC50 results indicate that the ternary complexes havepromised inhibition of HePG2 liver tumors [48 49]
Cell viability was assessed by themitochondrial-dependentreduction of yellow MTT (3-(45-dimethylthiazol-2-yl)-25-
108K096K084K072K060K048K036K024K012K000K
000 100 200 300 400 500 600 700 800 900
Cu Kβ
Cu Kα
Cu L
O KC K
(a) (b)
Figure 8 EDX and SEM images of CuO obtained by thermal decomposition at 550Cdeg starting from copper glutamic arginine mixed ligandscomplex
135K120K105K090K075K060K045K030K015K000K
000 100 200 300 400 500 600 700 800 900
O K
Co L Co Kα
Co Kβ
(a) (b)
Figure 9 EDX and SEM images of Co3O4 obtained by thermal decomposition at 550Cdeg starting from cobalt glutamic arginine mixedligands complex
Table 6 Antimicrobial activity of prepared ternary metal complexes
Sample tested microorganisms Glutamicacid L-arginine (1) (2) (3) (4) Standard
lowastNA no activity Values in bracket are the MIC values
12 Journal of Chemistry
diphenyl tetrazolium bromide) to insoluble purple formazan[45] (e prepared ternary metal complexes are of differentviability percentages as depicted in Figure 10 Data of bothligands are also included for comparison
Table 2S shows that the ligands have lower inhibition ofHePG2 than their metal ternary complexes (e coppercomplex introduces the highest inhibition
Additionally Table 7 summarizes some computedelectrical reactivity [50] and thermodynamic propertiesfor Co(II) and Cu(II) complexes (as maximum andminimum IC50 of the four prepared ternary metalscomplexes) which are correlated with the inhibition ofhuman cancer cells and are useful to explain the roleplayed by molecular properties in inhibition of humancancer cells
(e simulated data summarized in Table 7 conclude thefollowing
(i) Cu complex is more energetically stable relative toCo complex by about minus265 kJmol
(ii) Cu complex is characterized by lower dipole mo-ment and lower polarizability relative to Co(II)complexes
(iii) Enthalpy and Gibbs free energy of the Cu complexesare more stable by about minus265 kJmol relative toCo(II) complex Lower entropy reflects lower degreeof randomness of Cu(II) complex
(iv) (e chemical potential (μprime) (negative of molecularelectronegativity) of Cu(II) complex is much higherthan that of Co(II) complex reflecting the enhancedreactivity of Cu(II) complex as nucleophile becauseμprime measures the escaping tendency of electrons fromthe complex (μprime (LUMO+HOMO)2) [50]
(v) Cu complex is characterized by lower hardness thanCo(II) complex Hardness measures the resistanceto electron transfer (η (LUMO-HOMO)2) [50]
It seems that more thermodynamically stable and lesspolar Cu complex exhibits that enhanced responsive elec-tron cloud transfer to the surrounding tumor relative to theCo(II) complex (ese quantitative molecular descriptors[50] explain the promising inhibition activity of the Cu(II)complex (e results are correlated with the above-discussedPES results which show that Cu complex could act asnucleophile whereas Co complex is of enhanced electro-philic nature
(e nucleophilicity of Cu complex (seeking for positivelycharged sites of the reactant) together with its electricalthermodynamic and molecular properties favors its prom-ising inhibition activity towards HePG2 cancer cell [51ndash53]
343 Corrosion Inhibition of Aluminum An assessment ofcorrosion rates and inhibition efficiency for aluminum withdifferent inhibitor concentrations were computed as followscorrosion rate Rcorr was computed using equation (5)
Rcorr M1 minusM2( 1113857(mg)
A cm2( ) times t(h) (5)
where M1 weight (g) before immersion M2 weight (g)after immersion A area (cm2) of the specimen andt exposure time (h)
(e inhibition efficiency (IE) was evaluated usingequation (6)
IE Rblank minusRinh
Rblank1113890 1113891 times 100 (6)
120
60
100
80
60
40
20
00 10 20 30 40 50
GlutamicLarginineCu(II)
Ni(II)Co(II)Zn(II)
Figure 10 Cell viability of (HePG2) at different concentrations of ligands and the prepared metal complexes
Table 7 Simulated electrical properties of complexes studied exhibiting enhanced inhibition of HePG2
where Rblank corrosion rates in the absence of inhibitor andRinh corrosion rates in the presence of inhibitor [16]
Table 8 shows the calculated corrosion rates and inhibitionefficiencies of aluminum specimens in aqueous solution of 1MHCl as the corrosive medium in absence and presence ofmixed ligands and their ternary metal complexes at differenttemperatures (293 ndash313) K for 7 hours of each concentrationFigure 6S shows that as the concentration of ligands and theircomplexes increases Rcorr decreases and IE increases formixed ligands and their metal complexes acted as more ef-ficient inhibitors than their mixed ligands alone
344 Adsorption Isotherms and the +ermodynamic Acti-vation Parameters (e metal surface coverage degree(θIE100) was subjected to different adsorption iso-therms (e well fit for weight loss data is obtained forLangmuir adsorption isotherm Figure 11
Table 8 Corrosion parameters for aluminum in aqueous solution of 1M HCl in the absence and presence of different concentrations ofmixed ligands and their metal complexes at different temperatures for 7 hrs
Inhibitors C (times10minus2M)Corrosion rate times10minus4
Figure 11 Langmuir adsorption isotherms of the mixed ligands(L) and their metal complexes
14 Journal of Chemistry
(e temperature effect (293ndash313 K) on aluminum weightloss inhibition may be attributed to two main mechanismsphysical and chemical adsorption [37] (e suggested mech-anisms are obtained as the temperature increases the efficiencydecreases for mixed ligands but increases for their metalcomplexes depending on the nature of bond formation be-tween the mixed ligands and aluminum surface which isdifferent from the nature of bond formation between metalcomplexes and the aluminum surface [16] Arrhenius equation(7) gives the relation between the corrosion rate andtemperature
lnRcorr lnAminusElowast
RT (7)
where A is the Arrhenius factor Elowast is the apparent activationenergy of the corrosion process R is the rate gas constant andT is the absolute temperature (e straight line slope oflogRcorr vs 1T for aluminum 1M HCl at 4times10minus4molL after7 h is minusElowast2303R for the inhibitors (Figure 12)
(e activation thermodynamic parameters for alumi-num dissolution could be obtained from the transition stateequation (8)
lnRcorr
T1113874 1113875 ln
R
Nh1113874 1113875 +
ΔSlowast
R1113888 1113889minus
ΔHlowast
RT1113888 1113889 (8)
where the entropy of activation ∆Slowast and the apparent en-thalpy of activation ∆Hlowast can be obtained from the intercept
3150
02
04
06
logR
corr
(gmiddoth
ndash1middotcm
ndash1)
08
1
12
32 325 331000T(Kndash1)
335 34 345
BlankMix ligandsZn2+
Co2+Ni2+Cu2+
Figure 12 Arrhenius of log corrosion rate (Rcorr) vs 1T for aluminum in 1M HCl without and with 004times10minus2MLminus1 of inhibitors (mixedligands and their metal complexes)
Table 9 (ermodynamic parameters for the adsorption of (004times10minus2)ML mixed ligands and their metal complexes on aluminum metalin aqueous solution of 1M HCl at different temperatures for 7 hrs
and the slope for the straight line of the relation betweenln(RcorrT) vs (1T) respectively N is Avogadrorsquos numberand h is Planckrsquos constant (e Gibbs free energy of acti-vation ∆Glowast can be detected by equation (9)
ΔGlowast ΔHlowast minusTΔSlowast (9)
Table 9 shows the thermodynamic parameters for theadsorption of mixed ligands and their metal complexes (epositive value of ∆Hlowast indicated the endothermic property ofdissolution process nature for aluminum in the acidicmedium [54]
However the blank ΔHlowast value is higher than the in-hibitor metal complexes which indicated that the inhibitionefficiency generally increases with increasing temperature(e association step is the rate-determining step rather thana dissociation process in presence of the metal complexesinhibitors due to the negative values of ΔSlowast It is known thatthe values of ΔGlowast above 40 kJmiddotmolminus1 are referred to chargetransfer from the inhibitor molecules into aluminum surfaceto form coordinated compound on the Al surface whichblocks it against corrosion process by different degrees Alsothe chemical adsorption process mechanism is confirmed bythe values of ΔGlowast above 40 kJmiddotmolminus1 [16 54ndash56]
4 Conclusions
Novel coordination materials of ternary divalent metalions (Cu(II) Ni(II) Co(II) and Zn(II)) chelated by thebidentate glutamic acid (Glu) and L-arginine (Arg) aminoacids are synthesized and characterized (e metal ionscomplexes are modelled using density DFT and TD-DFTtheory Computed molecular and spectroscopic (IR UV-Vis and EPR) properties validated the experimental re-sults (e used computational methods are capable ofproviding good structural descriptions for the TM com-plexes Consistent with the experimental properties theoptimized structures of the complexes [Cu(II) Glu-Arg]and [Co(II) Glu-Arg (H2O)2] reveal that symmetry en-vironment of Cu(II) exhibits slightly distorted squareplanar shape whereas Co(II)-complex has a distortedoctahedral (where Co(II) central ion is of C4v-localsymmetry) Spectral properties of [Ni(II) Glu-Arg(H2O)2] and [ZnmiddotGlumiddotArgmiddot(H2O)2] complexes indicatethat they have similar structure as Co(II) complex All thestudied ternary metal complexes are of different anti-fungal activities ranging from moderate to weak withoutpractically noticed inhibitory effects whereas antibacte-rial activities of all studied metal complexes show sig-nificant effects
Cytotoxicity studies against (HePG2) reveal the prom-ising potentiality of Cu(II) complex as inhibitor of cancercells(e results are correlated with the computed moleculardescriptors including dipole moment polarizability ther-modynamics and reactivity properties as well as the PESmaps
(e corrosion inhibition of aluminum metal specimensin 1M HCl is efficiently achieved by mixed ligands and theirmetal complexes studied
Data Availability
(e data used to support the findings of this study areavailable from the corresponding author upon request
Conflicts of Interest
(e authors declare that they have no conflicts of interest
Supplementary Materials
(e supplementary materials consist of six figures and twotables to further clarify the structures and trends of the newlyprepared metal ternary complexes (SupplementaryMaterials)
References
[1] Z Ozturk D A Kose A Asan et al ldquoPorous metal-organicCu(II) complex of L-Arginine 2synthesis characterizationhydrogen storage properties and molecular simulation cal-culationsrdquo Hittite Journal of Science and Engineering vol 1no 1 pp 1ndash5 2014
[2] S A Lahsasni R A Ammar M F Amin et al ldquoMixed-ligandcomplex formation of Cu(II) with 12- diphenylethylenedi-amine as primary ligand and amino acids as secondary li-gandsrdquo International Journal of Electrochemical Sciencevol 7 pp 7699ndash7711 2012
[3] H Sigel B P Operschall S S Massoud B Song andR Griesser ldquoEvidence for intramolecular aromatic-ringstacking in the physiological pH range of the mono-deprotonated xanthine residue in mixed-ligand complexescontaining xanthosinate 5prime-monophosphate (XMP)rdquo DaltonTransactions vol 46 no 46 pp 5521ndash5529 2006
[4] S Udhayakumar K G Shankar S Sowndarya S VenkateshC Muralidharan and C Rose ldquol-Arginine intercedes bio-crosslinking of a collagen-chitosan 3D-hybrid scaffold fortissue engineering and regeneration in silico in vitro and invivo studiesrdquo RSC Advances vol 7 no 40 pp 25070ndash250882017
[5] P K Datta M Chandra and A K Dey ldquoTernary complexesof copper(II) nickel(II) and zinc(II) with nitrilotriacetic acidas a primary ligand and some phenolic acids as secondaryligandsrdquo Transition Metal Chemistry vol 5 no 1ndash3 1980
[6] J S Woertink L Tian D Maiti et al ldquoSpectroscopic andcomputational studies of an end-on bound superoxo-Cu(II)complex geometric and electronic factors that determine theground staterdquo Inorganic Chemistry vol 49 no 20pp 9450ndash9459 2010
[7] S Dutta S Ray K Nagarajan et al ldquoGlutamic acid analoguesused as potent anticancer a reviewrdquo Der Pharma Chemicavol 3 no 2 pp 263ndash272 2011
[8] T Sismanoglu S Pura and A Bastug ldquoBinary and ternarymetal complexes of Congo red with amino acidsrdquo Dyes andPigments vol 70 no 2 pp 136ndash142 2006
[9] R N Patel H C Pandey K B Pandeya et al ldquoMixed ligandcomplex formation of nickel(II)copper(II) and zinc(II) withsome amino acids and imidazolesrdquo Indian Journal ofChemistry-Section A Inorganic Physical +eoretical andAnalytical Chemistry vol 38 no 8 pp 850ndash853 1999
[10] L Meng and Z Lin ldquoComplexations of alkalialkaline earthmetal cations with gaseous glutamic acidrdquo Computational and+eoretical Chemistry vol 1039 pp 1ndash10 2014
16 Journal of Chemistry
[11] L D Pinto P A L Puppin V M Behring O C AlvesN A Rey and J Felcman ldquoSolution and solid state study ofcopper(II) ternary complexes containing amino acids of in-terest for brain biochemistry-2 homocysteine with aspartateglutamate or methioninerdquo Inorganica Chimica Acta vol 386pp 60ndash67 2012
[12] A Wojciechowska A Ggor and W Zierkiewicz ldquoChiraloctahedral complexes of Co(III) as catalysts for asymmetricepoxidation of chalcones under phase transfer conditionsrdquoRSC Advances vol 5 no 46 pp 36295ndash36306 2015
[13] B M Weckhuysen A A Verberckmoes L Fu andR A Schoonheydt ldquoZeolite-encapsulated copper(II) aminoacid complexes synthesis spectroscopy and catalysisrdquo Journalof Physical Chemistry vol 100 no 22 pp 9456ndash9461 1996
[14] K Y El-Baradie N A El-Wakiel and H A El-GhamryldquoSynthesis characterization and corrosion inhibition in acidmedium ofl-histidine Schiff base complexesrdquo Applied Or-ganometallic Chemistry vol 29 no 3 pp 117ndash125 2015
[15] S S R Anthony and R Susai ldquoInhibition of corrosion ofcarbon steel in well water by arginine-Zn2+ systemrdquo Journal ofElectrochemical Science and Engineering vol 2 no 2pp 91ndash104 2012
[16] E H Isamil F F AlBlewi N Soliman and M M H Khalilldquo(ermal studies and mass loss inhibition for some newmixed amino acid metal complexes with their applicationsrdquoJournal of +ermal Analysis and Calorimetry vol 125 no 1pp 289ndash300 2016
[17] F Neese ldquo(e ORCA program system 4012rdquo Wiley In-terdisciplinary Reviews Computational Molecular Sciencevol 2 no 1 pp 73ndash78 2012
[18] S Grimme S Ehrlich and L Goerigk ldquoEffect of the dampingfunction in dispersion corrected density functional theoryrdquoJournal of Computational Chemistry vol 32 no 7pp 1456ndash1465 2011
[19] S Grimme J Antony S Ehrlich and H Krieg ldquoA consistentand accurate ab initio parametrization of density functionaldispersion correction (DFT-D) for the 94 elements H-Purdquo+e Journal of Chemical Physics vol 132 no 15 article154104 2010
[20] F Weigend ldquoHartree-Fock exchange fitting basis sets for H toRnrdquo Journal of Computational Chemistry vol 29 no 2pp 167ndash175 2008
[21] F Neese F Wennmohs and A Hansen ldquoEfficient ap-proximate and parallel Hartree-Fock and hybrid DFT cal-culations A lsquochain-of-spheresrsquo algorithm for the Hartree-Fock exchangerdquo Chemical Physics vol 356 no 1ndash3pp 98ndash109 2009
[22] R Izsak and F Neese ldquoAn overlap fitted chain of spheresexchange methodrdquo Journal of Chemical Physics vol 135no 14 article 144105 2011
[23] T Petrenko S Kossmann and F Neese ldquoEfficient time-dependent density functional theory approximations forhybrid density functionals analytical gradients and paralle-lizationrdquo Journal of Chemical Physics vol 134 no 5 article054116 2011
[24] A V Marenich C J Cramer and D G Truhlar ldquoUniversalsolvation model based on solute electron density and on acontinuum model of the solvent defined by the bulk dielectricconstant and atomic surface tensionsrdquo Journal of PhysicalChemistry B vol 113 no 18 pp 6378ndash96 2009
[25] S Donovan C Stiefbold and K Sprague ldquoChapter 3Chemical properties of amino acids and identification ofunknown amino acidsrdquo in Proceedings of the 17 thWorkshopConference of the Association for Biology
Laboratory Education (ABLE) vol 17 pp 35ndash70 Bain-bridge GA USA March 1996
[26] C C Wagner J Enrique and C Claudia ldquoVibrational andmagnetic properties of a CuMg glutamate complexrdquoArgentina Acta Farm Bonaerense vol 22 no 2 pp 137ndash1422003
[27] M Arif R Sur and M Arshad ldquoStudies on the thermaldecomposition of copper (II) flouride complexes with variousamino acids in nitrogen atmosphererdquo Turkish Journal ofChemistry vol 25 pp 73ndash79 2001
[28] A Ghosh M J Tucker and R M Hochstrasser ldquoIdentifi-cation of arginine residues in peptides by 2d-IR echo spec-troscopyrdquo Journal of Physical Chemistry A vol 115 no 34pp 9731ndash9738 2011
[29] K Nakamoto Infrared Spectra of Inorganic and CoordinationCompounds Part B Wiley-Interscience New York NY USA5th edition 1997
[30] E Santi M H Torre E Kremer S B Etcheverry andE J Baran ldquoVibrational spectra of the copper(II) and nick-el(II) complexes of piroxicamrdquo Vibrational Spectroscopyvol 5 no 3 pp 285ndash293 1993
[31] H N Aliyu and A S Mohammed ldquoSynthesis spectropho-tometric and biological activity of nickel (II) and copper (II)complexes with schiff base derived from acetylacetone andhistidinerdquo Global Advanced Research Journal of Microbiologyvol 1 no 5 pp 67ndash71 2012
[32] J S Murray and P Politzer ldquo(e electrostatic potential anoverviewrdquo Wiley Interdisciplinary Reviews ComputationalMolecular Science vol 1 no 2 pp 153ndash163 2011
[33] E R Souaya M M H Khalil and E H Ismail ldquoSynthesis andcharacterization of ternary complexes of certain hydroxylacids and their biological applicationsrdquo Research Journal ofPharmaceutical Biological and Chemical Sciences vol 5 no 4pp 18ndash30 2014
[34] N N Greenwood and A Earnshaw A Review of Chemistry ofthe Elements Pergamon Press Oxford UK 1984
[35] V Reddy N Patil and S D Angadi ldquoSynthesis character-ization and antimicrobial activity of Cu(II) Co(II) and Ni(II)complexes with ON and S Donor ligandsrdquo E-Journal ofChemistry vol 5 no 3 pp 577ndash583 2008
[36] F A Cotton G Wilkinson C A Murillo et al Advances inSchiff Base Chemistry Wiley New York NY USA 6th edi-tion 1999
[37] M M H Khalil E H Ismail S A Azim and E R SouayaldquoSynthesis characterization and thermal analysis of ternarycomplexes of nitrilotriacetic acid and alanine or phenylala-nine with some transition metalsrdquo Journal of +ermalAnalysis and Calorimetry vol 101 no 1 pp 129ndash135 2010
[38] F Mabbs and D Colisson Electron Paramagnetic Resonanceof D Transition Metal Compounds Vol 102 ElsevierAmsterdam Netherlands 1992
[39] M M H Khalil E R Souaya E H Ismail et al ldquoTernarytransition metal complexes of nitrilotriacetic acid and valineor leucine synthesis and biological applicationsrdquo ChineseJournal of Inorganic Chemistry vol 29 no 9 pp 1969ndash19782013
[40] I M Weiss C Muth R Drumm and H O K Kirchnerldquo(ermal decomposition of the amino acids glycine cysteineaspartic acid asparagine glutamic acid glutamine arginineand histidinerdquo BMC Biophysics vol 11 no 1 2018
[41] A M Petrosyan V V Ghazaryan G Giester and M FleckldquoSulfamates and methanesulfonates of L-arginine and L-his-tidinerdquo Journal of Molecular Structure vol 1163 pp 114ndash1272018
Journal of Chemistry 17
[42] T Kavitha S Haider T Kamal and M Ul-Islam ldquo(ermaldecomposition of metal complex precursor as route to thesynthesis of Co3O4 nanoparticles antibacterial activity andmechanismrdquo Journal of Alloys and Compounds vol 704pp 296ndash302 2017
[43] E M M Ibrahim L H Abdel-Rahman A M Abu-DiefA Elshafaie S K Hamdan and A M Ahmed ldquo(e synthesisof CuO andNiO nanoparticles by facile thermal decompositionof metal-Schiff base complexes and an examination of theirelectric thermoelectric and magnetic Propertiesrdquo MaterialsResearch Bulletin vol 107 pp 492ndash497 2018
[44] S Farhadi M Javanmard and G Nadri ldquoCharacterization ofcobalt oxide nanoparticles prepared by the thermal de-compositionrdquo Acta Chimica Slovenica vol 63 pp 335ndash3432016
[45] E M Zayed E H Ismail G G Mohamed M M H Khaliland A B Kamel ldquoSynthesis spectroscopic and structuralcharacterization and antimicrobial studies of metal com-plexes of a new hexadentate Schiff base ligand Spectropho-tometric determination of Fe(III) in water samples using arecovery testrdquo Monatshefte fur Chemie-Chemical Monthlyvol 145 no 5 pp 755ndash765 2014
[46] V Milacic D Chen L Ronconi K R Landis-PiwowarD Fregona and Q P Dou ldquoA novel anticancer gold(III)dithiocarbamate compound inhibits the activity of a purified20S proteasome and 26S proteasome in human breast cancercell cultures and xenograftsrdquo Cancer Research vol 66 no 21pp 10478ndash10486 2006
[47] T Mosmann ldquoRapid colorimetric assay for cellular growthand survival application to proliferation and cytotoxicityassaysrdquo Journal of Immunological Methods vol 65 no 1-2pp 55ndash63 1983
[48] R L Siegel K D Miller and A Jemal ldquoCancer statistics2018rdquo CA A Cancer Journal for Clinicians vol 68 no 1pp 7ndash30 2018
[49] S Chattopadhyay S P Chakraborty D Laha et al ldquoSurface-modified cobalt oxide nanoparticles new opportunities foranti-cancer drug developmentrdquo Cancer Nanotechnol vol 3no 1-6 pp 13ndash23 2012
[50] F Zielinski V Tognetti and L Joubert ldquoCondensed de-scriptors for reactivity a methodological studyrdquo ChemicalPhysics Letters vol 527 pp 67ndash72 2012
[51] H Wang Y He Q Yan et al ldquoCorrelation between thedielectric properties and biological activities of human ex vivohepatic tissuerdquo Physics in Medicine and Biology vol 60 no 6pp 2603ndash2617 2015
[52] F Tao F Fu F You et al ldquo(e correlation between dielectricproperties and microstructure of femoral bone in rats withdifferent bone qualitiesrdquo Annals of Biomedical Engineeringvol 42 no 6 pp 1238ndash1249 2014
[53] L Gun D Ning and Z Liang ldquoEffective permittivity ofbiological tissue comparison of theoretical model and ex-perimentrdquo Mathematical Problems in Engineering vol 2017Article ID 7249672 2017
[54] E I Ating S A Umoren I I Udousoro E E Ebenso andA P Udoh ldquoLeaves extract of Ananas sativumas greencorrosion inhibitor for aluminium in hydrochloric acid so-lutionsrdquo Green Chemistry Letters and Reviews vol 3 no 2pp 61ndash68 2010
[55] E Hamed ldquoStudies of the corrosion inhibition of copper inNa2SO4 solution using polarization and electrochemicalimpedance spectroscopyrdquo Materials Chemistry and Physicsvol 121 no 1-2 pp 70ndash76 2010
[56] H Zarrok H Oudda A Zarrouk et al ldquoWeight loss mea-surement and theoretical study of new pyridazine compoundas corrosion inhibitor for C38 steel in hydrochloric acidsolutionrdquo Der Pharma Chemica vol 3 no 6 pp 576ndash5902011
18 Journal of Chemistry
TribologyAdvances in
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
International Journal ofInternational Journal ofPhotoenergy
Hindawiwwwhindawicom Volume 2018
Journal of
Chemistry
Hindawiwwwhindawicom Volume 2018
Advances inPhysical Chemistry
Hindawiwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2018
Bioinorganic Chemistry and ApplicationsHindawiwwwhindawicom Volume 2018
Figure 6 TG and DTG of (a) [Co(glu)(arg)(H2O)2]middot05H2O (b) [Ni(glu)(arg)(H2O)2]middot05H2O (c) [Cu(glu)((arg)]middotH2O and(d) [ZnmiddotGlumiddotArgmiddot(H2O)2]middotH2O
10 Journal of Chemistry
estimated using well-known DebyendashScherrer formula usingthe full width at half maximum (FWHM) of the (111) peaksin the XRD K(α) is the wavelength of X-ray source(15406 A 015406 nm) β∆θ is the full width at halfmaximum (FWHM 01378) and θ 387 is the diffractionangle corresponding to the lattice plane (111) which gives Dsim143ndash204plusmn 08 nm patterns [42ndash44]
(e pattern of XRD for cobalt oxide nanoparticles showscharacteristic peaks at 2θ values at 1898deg 3127deg 3682deg3848deg 4478deg 5568deg 5934deg 6521deg and 7731deg which arecorresponding to their indices (111) (220) (311) (400) (511)and (440) in agreement with JCPDS Card No 76ndash1802 (ispattern confirms the phase formation of cobalt oxidenanoparticle Figure 7(b) (e average size of the Co3O4particles was calculated by the DebyendashScherrer equationDK(α) λ(β cos θ) whereD is the average crystalline size λ isthe wavelength of CuKα θ is Braggrsquos angle and β is the fullwidth at half maximum (FWHM) of the diffraction peak (eaverage dimension D is sim147ndash182plusmn 06 nm at 2θ 3682degwhich is the intense peak [44]
332 EDX of Nano CuO (e synthesized nano copperoxide is confirmed by the EDX spectrum and SEM imagemeasurement shown in Figure 8 which confirms the highestformation percent of CuO and traces of copper carbide (eSEM image for nano copper oxide CuO shows a mixingnanosize 270sim1079 nm [42 43]
333 EDX of Nano Cobaltosic Oxide (e synthesized nanocobalt oxide is confirmed by the EDX spectrum measure-ment shown in Figure 9 which confirms the highest for-mation percent of cobaltosic oxide Co3O4 and traces ofcobalt carbide (e SEM image for nano cobaltosic oxideCo3O4 shows a mixing nanosize 318ndash8543 nm
34 Applications
341 Biological Activity Mixed ligand ternary complexeshave been examined for their in vitro antimicrobial activity(is investigation was performed using the diffusion agartechnique (Figure 5S) (e assays collection included
g-negative (Pseudomonas aeruginosa RCMB 010043 andEscherichia coli RCMB 010052) pathogenic bacteria usingGentamicin 5mgml as a reference compound and g-pos-itive (Streptococcus pneumoniae RCMB 010010 and Bacillissubtilis RCMB 010067) pathogenic bacteria using Ampi-cillin 5mgml as a reference compound It was also in-cluded four fungi (Aspergillus fumigatus RCMB 02568Syncephalastrum racemosum RCMB 05922 Geotrichumcandidum RCMB 05097 and Candida albicans RCMB05036) using Amphotericin B 5mgml as a referencecompound [30 45]
(e inhibitory effects of the used ligands and theirternary polymer complexes against the used organisms aregiven in Table 6 In general the used ligands did not displayantifungal or antibacterial inhibitory
For antifungal assay examination and based on theminimum inhibitory concentration (MIC) values it is foundthat the inhibitory effect of all the ternary complexes varyfrom moderate to weak against Amphotericin B controlexcept in the case of Candida albicans (RCMB 05036) whichis not affected by both cobalt and zinc complexes
(e antibacterial activities of the obtained ternarycomplexes are determined in terms of MIC values As shownin Table 6 all complexes display moderate activities againstStreptococcus pneumonia (RCMB 010010) and Bacillis sub-tilis RCMB 010067 (e growth of the gram-negative bac-teria Pseudomonas aeruginosa RCMB 010043 andEscherichia coli RCMB 010052 is extremely affected by bothcopper and nickel complexes which display strong inhibitionagainst the gram-negative pathogenic bacteria with MICvalue less than the Gentamicin control (e remainingcomplexes do not display the same behavior during theassay
342 Cytotoxicity One of the fundamental goals in me-dicinal chemistry is the development of new anticancer andantimicrobial therapeutic agents Cancer treatment usingmetal-based drugs is one of the very effective strategies as themetal ions are capable of binding to nucleic acids stereo-specifically with varying strength
In vitro anticancer activity evaluation of the newlysynthesized compounds was carried out against human
Cou
nts
400
300
200
100
010 20 30 40
Angles (deg2θ)50 60 70
(a)
Cou
nts
100
50
010 20 30 40
Angles (deg2θ)50 60 70
(b)
Figure 7 XRD pattern of (a) copper oxide CuO and (b) cobalt oxide Co3O4 prepared by thermal decomposition at 550Cdeg starting frommetal glutamic arginine mixed ligands complex
Journal of Chemistry 11
cancer cell lines hepatocellular carcinoma (HePG2) becauseliver cancer is the third most common cause of death incancer using MTT method [26 46 47]
Doxorubicin HCl is one of the most effective anti-cancer agents is used as a reference drug in this study (eobtained results from Table 2S indicated that most of thesemoleculesrsquo behavior can be observed from the values of the
half maximal inhibitory concentration IC50 whichfor glutamic and arginine are 167 and 376 μgmlrespectively
IC50 results indicate that the ternary complexes havepromised inhibition of HePG2 liver tumors [48 49]
Cell viability was assessed by themitochondrial-dependentreduction of yellow MTT (3-(45-dimethylthiazol-2-yl)-25-
108K096K084K072K060K048K036K024K012K000K
000 100 200 300 400 500 600 700 800 900
Cu Kβ
Cu Kα
Cu L
O KC K
(a) (b)
Figure 8 EDX and SEM images of CuO obtained by thermal decomposition at 550Cdeg starting from copper glutamic arginine mixed ligandscomplex
135K120K105K090K075K060K045K030K015K000K
000 100 200 300 400 500 600 700 800 900
O K
Co L Co Kα
Co Kβ
(a) (b)
Figure 9 EDX and SEM images of Co3O4 obtained by thermal decomposition at 550Cdeg starting from cobalt glutamic arginine mixedligands complex
Table 6 Antimicrobial activity of prepared ternary metal complexes
Sample tested microorganisms Glutamicacid L-arginine (1) (2) (3) (4) Standard
lowastNA no activity Values in bracket are the MIC values
12 Journal of Chemistry
diphenyl tetrazolium bromide) to insoluble purple formazan[45] (e prepared ternary metal complexes are of differentviability percentages as depicted in Figure 10 Data of bothligands are also included for comparison
Table 2S shows that the ligands have lower inhibition ofHePG2 than their metal ternary complexes (e coppercomplex introduces the highest inhibition
Additionally Table 7 summarizes some computedelectrical reactivity [50] and thermodynamic propertiesfor Co(II) and Cu(II) complexes (as maximum andminimum IC50 of the four prepared ternary metalscomplexes) which are correlated with the inhibition ofhuman cancer cells and are useful to explain the roleplayed by molecular properties in inhibition of humancancer cells
(e simulated data summarized in Table 7 conclude thefollowing
(i) Cu complex is more energetically stable relative toCo complex by about minus265 kJmol
(ii) Cu complex is characterized by lower dipole mo-ment and lower polarizability relative to Co(II)complexes
(iii) Enthalpy and Gibbs free energy of the Cu complexesare more stable by about minus265 kJmol relative toCo(II) complex Lower entropy reflects lower degreeof randomness of Cu(II) complex
(iv) (e chemical potential (μprime) (negative of molecularelectronegativity) of Cu(II) complex is much higherthan that of Co(II) complex reflecting the enhancedreactivity of Cu(II) complex as nucleophile becauseμprime measures the escaping tendency of electrons fromthe complex (μprime (LUMO+HOMO)2) [50]
(v) Cu complex is characterized by lower hardness thanCo(II) complex Hardness measures the resistanceto electron transfer (η (LUMO-HOMO)2) [50]
It seems that more thermodynamically stable and lesspolar Cu complex exhibits that enhanced responsive elec-tron cloud transfer to the surrounding tumor relative to theCo(II) complex (ese quantitative molecular descriptors[50] explain the promising inhibition activity of the Cu(II)complex (e results are correlated with the above-discussedPES results which show that Cu complex could act asnucleophile whereas Co complex is of enhanced electro-philic nature
(e nucleophilicity of Cu complex (seeking for positivelycharged sites of the reactant) together with its electricalthermodynamic and molecular properties favors its prom-ising inhibition activity towards HePG2 cancer cell [51ndash53]
343 Corrosion Inhibition of Aluminum An assessment ofcorrosion rates and inhibition efficiency for aluminum withdifferent inhibitor concentrations were computed as followscorrosion rate Rcorr was computed using equation (5)
Rcorr M1 minusM2( 1113857(mg)
A cm2( ) times t(h) (5)
where M1 weight (g) before immersion M2 weight (g)after immersion A area (cm2) of the specimen andt exposure time (h)
(e inhibition efficiency (IE) was evaluated usingequation (6)
IE Rblank minusRinh
Rblank1113890 1113891 times 100 (6)
120
60
100
80
60
40
20
00 10 20 30 40 50
GlutamicLarginineCu(II)
Ni(II)Co(II)Zn(II)
Figure 10 Cell viability of (HePG2) at different concentrations of ligands and the prepared metal complexes
Table 7 Simulated electrical properties of complexes studied exhibiting enhanced inhibition of HePG2
where Rblank corrosion rates in the absence of inhibitor andRinh corrosion rates in the presence of inhibitor [16]
Table 8 shows the calculated corrosion rates and inhibitionefficiencies of aluminum specimens in aqueous solution of 1MHCl as the corrosive medium in absence and presence ofmixed ligands and their ternary metal complexes at differenttemperatures (293 ndash313) K for 7 hours of each concentrationFigure 6S shows that as the concentration of ligands and theircomplexes increases Rcorr decreases and IE increases formixed ligands and their metal complexes acted as more ef-ficient inhibitors than their mixed ligands alone
344 Adsorption Isotherms and the +ermodynamic Acti-vation Parameters (e metal surface coverage degree(θIE100) was subjected to different adsorption iso-therms (e well fit for weight loss data is obtained forLangmuir adsorption isotherm Figure 11
Table 8 Corrosion parameters for aluminum in aqueous solution of 1M HCl in the absence and presence of different concentrations ofmixed ligands and their metal complexes at different temperatures for 7 hrs
Inhibitors C (times10minus2M)Corrosion rate times10minus4
Figure 11 Langmuir adsorption isotherms of the mixed ligands(L) and their metal complexes
14 Journal of Chemistry
(e temperature effect (293ndash313 K) on aluminum weightloss inhibition may be attributed to two main mechanismsphysical and chemical adsorption [37] (e suggested mech-anisms are obtained as the temperature increases the efficiencydecreases for mixed ligands but increases for their metalcomplexes depending on the nature of bond formation be-tween the mixed ligands and aluminum surface which isdifferent from the nature of bond formation between metalcomplexes and the aluminum surface [16] Arrhenius equation(7) gives the relation between the corrosion rate andtemperature
lnRcorr lnAminusElowast
RT (7)
where A is the Arrhenius factor Elowast is the apparent activationenergy of the corrosion process R is the rate gas constant andT is the absolute temperature (e straight line slope oflogRcorr vs 1T for aluminum 1M HCl at 4times10minus4molL after7 h is minusElowast2303R for the inhibitors (Figure 12)
(e activation thermodynamic parameters for alumi-num dissolution could be obtained from the transition stateequation (8)
lnRcorr
T1113874 1113875 ln
R
Nh1113874 1113875 +
ΔSlowast
R1113888 1113889minus
ΔHlowast
RT1113888 1113889 (8)
where the entropy of activation ∆Slowast and the apparent en-thalpy of activation ∆Hlowast can be obtained from the intercept
3150
02
04
06
logR
corr
(gmiddoth
ndash1middotcm
ndash1)
08
1
12
32 325 331000T(Kndash1)
335 34 345
BlankMix ligandsZn2+
Co2+Ni2+Cu2+
Figure 12 Arrhenius of log corrosion rate (Rcorr) vs 1T for aluminum in 1M HCl without and with 004times10minus2MLminus1 of inhibitors (mixedligands and their metal complexes)
Table 9 (ermodynamic parameters for the adsorption of (004times10minus2)ML mixed ligands and their metal complexes on aluminum metalin aqueous solution of 1M HCl at different temperatures for 7 hrs
and the slope for the straight line of the relation betweenln(RcorrT) vs (1T) respectively N is Avogadrorsquos numberand h is Planckrsquos constant (e Gibbs free energy of acti-vation ∆Glowast can be detected by equation (9)
ΔGlowast ΔHlowast minusTΔSlowast (9)
Table 9 shows the thermodynamic parameters for theadsorption of mixed ligands and their metal complexes (epositive value of ∆Hlowast indicated the endothermic property ofdissolution process nature for aluminum in the acidicmedium [54]
However the blank ΔHlowast value is higher than the in-hibitor metal complexes which indicated that the inhibitionefficiency generally increases with increasing temperature(e association step is the rate-determining step rather thana dissociation process in presence of the metal complexesinhibitors due to the negative values of ΔSlowast It is known thatthe values of ΔGlowast above 40 kJmiddotmolminus1 are referred to chargetransfer from the inhibitor molecules into aluminum surfaceto form coordinated compound on the Al surface whichblocks it against corrosion process by different degrees Alsothe chemical adsorption process mechanism is confirmed bythe values of ΔGlowast above 40 kJmiddotmolminus1 [16 54ndash56]
4 Conclusions
Novel coordination materials of ternary divalent metalions (Cu(II) Ni(II) Co(II) and Zn(II)) chelated by thebidentate glutamic acid (Glu) and L-arginine (Arg) aminoacids are synthesized and characterized (e metal ionscomplexes are modelled using density DFT and TD-DFTtheory Computed molecular and spectroscopic (IR UV-Vis and EPR) properties validated the experimental re-sults (e used computational methods are capable ofproviding good structural descriptions for the TM com-plexes Consistent with the experimental properties theoptimized structures of the complexes [Cu(II) Glu-Arg]and [Co(II) Glu-Arg (H2O)2] reveal that symmetry en-vironment of Cu(II) exhibits slightly distorted squareplanar shape whereas Co(II)-complex has a distortedoctahedral (where Co(II) central ion is of C4v-localsymmetry) Spectral properties of [Ni(II) Glu-Arg(H2O)2] and [ZnmiddotGlumiddotArgmiddot(H2O)2] complexes indicatethat they have similar structure as Co(II) complex All thestudied ternary metal complexes are of different anti-fungal activities ranging from moderate to weak withoutpractically noticed inhibitory effects whereas antibacte-rial activities of all studied metal complexes show sig-nificant effects
Cytotoxicity studies against (HePG2) reveal the prom-ising potentiality of Cu(II) complex as inhibitor of cancercells(e results are correlated with the computed moleculardescriptors including dipole moment polarizability ther-modynamics and reactivity properties as well as the PESmaps
(e corrosion inhibition of aluminum metal specimensin 1M HCl is efficiently achieved by mixed ligands and theirmetal complexes studied
Data Availability
(e data used to support the findings of this study areavailable from the corresponding author upon request
Conflicts of Interest
(e authors declare that they have no conflicts of interest
Supplementary Materials
(e supplementary materials consist of six figures and twotables to further clarify the structures and trends of the newlyprepared metal ternary complexes (SupplementaryMaterials)
References
[1] Z Ozturk D A Kose A Asan et al ldquoPorous metal-organicCu(II) complex of L-Arginine 2synthesis characterizationhydrogen storage properties and molecular simulation cal-culationsrdquo Hittite Journal of Science and Engineering vol 1no 1 pp 1ndash5 2014
[2] S A Lahsasni R A Ammar M F Amin et al ldquoMixed-ligandcomplex formation of Cu(II) with 12- diphenylethylenedi-amine as primary ligand and amino acids as secondary li-gandsrdquo International Journal of Electrochemical Sciencevol 7 pp 7699ndash7711 2012
[3] H Sigel B P Operschall S S Massoud B Song andR Griesser ldquoEvidence for intramolecular aromatic-ringstacking in the physiological pH range of the mono-deprotonated xanthine residue in mixed-ligand complexescontaining xanthosinate 5prime-monophosphate (XMP)rdquo DaltonTransactions vol 46 no 46 pp 5521ndash5529 2006
[4] S Udhayakumar K G Shankar S Sowndarya S VenkateshC Muralidharan and C Rose ldquol-Arginine intercedes bio-crosslinking of a collagen-chitosan 3D-hybrid scaffold fortissue engineering and regeneration in silico in vitro and invivo studiesrdquo RSC Advances vol 7 no 40 pp 25070ndash250882017
[5] P K Datta M Chandra and A K Dey ldquoTernary complexesof copper(II) nickel(II) and zinc(II) with nitrilotriacetic acidas a primary ligand and some phenolic acids as secondaryligandsrdquo Transition Metal Chemistry vol 5 no 1ndash3 1980
[6] J S Woertink L Tian D Maiti et al ldquoSpectroscopic andcomputational studies of an end-on bound superoxo-Cu(II)complex geometric and electronic factors that determine theground staterdquo Inorganic Chemistry vol 49 no 20pp 9450ndash9459 2010
[7] S Dutta S Ray K Nagarajan et al ldquoGlutamic acid analoguesused as potent anticancer a reviewrdquo Der Pharma Chemicavol 3 no 2 pp 263ndash272 2011
[8] T Sismanoglu S Pura and A Bastug ldquoBinary and ternarymetal complexes of Congo red with amino acidsrdquo Dyes andPigments vol 70 no 2 pp 136ndash142 2006
[9] R N Patel H C Pandey K B Pandeya et al ldquoMixed ligandcomplex formation of nickel(II)copper(II) and zinc(II) withsome amino acids and imidazolesrdquo Indian Journal ofChemistry-Section A Inorganic Physical +eoretical andAnalytical Chemistry vol 38 no 8 pp 850ndash853 1999
[10] L Meng and Z Lin ldquoComplexations of alkalialkaline earthmetal cations with gaseous glutamic acidrdquo Computational and+eoretical Chemistry vol 1039 pp 1ndash10 2014
16 Journal of Chemistry
[11] L D Pinto P A L Puppin V M Behring O C AlvesN A Rey and J Felcman ldquoSolution and solid state study ofcopper(II) ternary complexes containing amino acids of in-terest for brain biochemistry-2 homocysteine with aspartateglutamate or methioninerdquo Inorganica Chimica Acta vol 386pp 60ndash67 2012
[12] A Wojciechowska A Ggor and W Zierkiewicz ldquoChiraloctahedral complexes of Co(III) as catalysts for asymmetricepoxidation of chalcones under phase transfer conditionsrdquoRSC Advances vol 5 no 46 pp 36295ndash36306 2015
[13] B M Weckhuysen A A Verberckmoes L Fu andR A Schoonheydt ldquoZeolite-encapsulated copper(II) aminoacid complexes synthesis spectroscopy and catalysisrdquo Journalof Physical Chemistry vol 100 no 22 pp 9456ndash9461 1996
[14] K Y El-Baradie N A El-Wakiel and H A El-GhamryldquoSynthesis characterization and corrosion inhibition in acidmedium ofl-histidine Schiff base complexesrdquo Applied Or-ganometallic Chemistry vol 29 no 3 pp 117ndash125 2015
[15] S S R Anthony and R Susai ldquoInhibition of corrosion ofcarbon steel in well water by arginine-Zn2+ systemrdquo Journal ofElectrochemical Science and Engineering vol 2 no 2pp 91ndash104 2012
[16] E H Isamil F F AlBlewi N Soliman and M M H Khalilldquo(ermal studies and mass loss inhibition for some newmixed amino acid metal complexes with their applicationsrdquoJournal of +ermal Analysis and Calorimetry vol 125 no 1pp 289ndash300 2016
[17] F Neese ldquo(e ORCA program system 4012rdquo Wiley In-terdisciplinary Reviews Computational Molecular Sciencevol 2 no 1 pp 73ndash78 2012
[18] S Grimme S Ehrlich and L Goerigk ldquoEffect of the dampingfunction in dispersion corrected density functional theoryrdquoJournal of Computational Chemistry vol 32 no 7pp 1456ndash1465 2011
[19] S Grimme J Antony S Ehrlich and H Krieg ldquoA consistentand accurate ab initio parametrization of density functionaldispersion correction (DFT-D) for the 94 elements H-Purdquo+e Journal of Chemical Physics vol 132 no 15 article154104 2010
[20] F Weigend ldquoHartree-Fock exchange fitting basis sets for H toRnrdquo Journal of Computational Chemistry vol 29 no 2pp 167ndash175 2008
[21] F Neese F Wennmohs and A Hansen ldquoEfficient ap-proximate and parallel Hartree-Fock and hybrid DFT cal-culations A lsquochain-of-spheresrsquo algorithm for the Hartree-Fock exchangerdquo Chemical Physics vol 356 no 1ndash3pp 98ndash109 2009
[22] R Izsak and F Neese ldquoAn overlap fitted chain of spheresexchange methodrdquo Journal of Chemical Physics vol 135no 14 article 144105 2011
[23] T Petrenko S Kossmann and F Neese ldquoEfficient time-dependent density functional theory approximations forhybrid density functionals analytical gradients and paralle-lizationrdquo Journal of Chemical Physics vol 134 no 5 article054116 2011
[24] A V Marenich C J Cramer and D G Truhlar ldquoUniversalsolvation model based on solute electron density and on acontinuum model of the solvent defined by the bulk dielectricconstant and atomic surface tensionsrdquo Journal of PhysicalChemistry B vol 113 no 18 pp 6378ndash96 2009
[25] S Donovan C Stiefbold and K Sprague ldquoChapter 3Chemical properties of amino acids and identification ofunknown amino acidsrdquo in Proceedings of the 17 thWorkshopConference of the Association for Biology
Laboratory Education (ABLE) vol 17 pp 35ndash70 Bain-bridge GA USA March 1996
[26] C C Wagner J Enrique and C Claudia ldquoVibrational andmagnetic properties of a CuMg glutamate complexrdquoArgentina Acta Farm Bonaerense vol 22 no 2 pp 137ndash1422003
[27] M Arif R Sur and M Arshad ldquoStudies on the thermaldecomposition of copper (II) flouride complexes with variousamino acids in nitrogen atmosphererdquo Turkish Journal ofChemistry vol 25 pp 73ndash79 2001
[28] A Ghosh M J Tucker and R M Hochstrasser ldquoIdentifi-cation of arginine residues in peptides by 2d-IR echo spec-troscopyrdquo Journal of Physical Chemistry A vol 115 no 34pp 9731ndash9738 2011
[29] K Nakamoto Infrared Spectra of Inorganic and CoordinationCompounds Part B Wiley-Interscience New York NY USA5th edition 1997
[30] E Santi M H Torre E Kremer S B Etcheverry andE J Baran ldquoVibrational spectra of the copper(II) and nick-el(II) complexes of piroxicamrdquo Vibrational Spectroscopyvol 5 no 3 pp 285ndash293 1993
[31] H N Aliyu and A S Mohammed ldquoSynthesis spectropho-tometric and biological activity of nickel (II) and copper (II)complexes with schiff base derived from acetylacetone andhistidinerdquo Global Advanced Research Journal of Microbiologyvol 1 no 5 pp 67ndash71 2012
[32] J S Murray and P Politzer ldquo(e electrostatic potential anoverviewrdquo Wiley Interdisciplinary Reviews ComputationalMolecular Science vol 1 no 2 pp 153ndash163 2011
[33] E R Souaya M M H Khalil and E H Ismail ldquoSynthesis andcharacterization of ternary complexes of certain hydroxylacids and their biological applicationsrdquo Research Journal ofPharmaceutical Biological and Chemical Sciences vol 5 no 4pp 18ndash30 2014
[34] N N Greenwood and A Earnshaw A Review of Chemistry ofthe Elements Pergamon Press Oxford UK 1984
[35] V Reddy N Patil and S D Angadi ldquoSynthesis character-ization and antimicrobial activity of Cu(II) Co(II) and Ni(II)complexes with ON and S Donor ligandsrdquo E-Journal ofChemistry vol 5 no 3 pp 577ndash583 2008
[36] F A Cotton G Wilkinson C A Murillo et al Advances inSchiff Base Chemistry Wiley New York NY USA 6th edi-tion 1999
[37] M M H Khalil E H Ismail S A Azim and E R SouayaldquoSynthesis characterization and thermal analysis of ternarycomplexes of nitrilotriacetic acid and alanine or phenylala-nine with some transition metalsrdquo Journal of +ermalAnalysis and Calorimetry vol 101 no 1 pp 129ndash135 2010
[38] F Mabbs and D Colisson Electron Paramagnetic Resonanceof D Transition Metal Compounds Vol 102 ElsevierAmsterdam Netherlands 1992
[39] M M H Khalil E R Souaya E H Ismail et al ldquoTernarytransition metal complexes of nitrilotriacetic acid and valineor leucine synthesis and biological applicationsrdquo ChineseJournal of Inorganic Chemistry vol 29 no 9 pp 1969ndash19782013
[40] I M Weiss C Muth R Drumm and H O K Kirchnerldquo(ermal decomposition of the amino acids glycine cysteineaspartic acid asparagine glutamic acid glutamine arginineand histidinerdquo BMC Biophysics vol 11 no 1 2018
[41] A M Petrosyan V V Ghazaryan G Giester and M FleckldquoSulfamates and methanesulfonates of L-arginine and L-his-tidinerdquo Journal of Molecular Structure vol 1163 pp 114ndash1272018
Journal of Chemistry 17
[42] T Kavitha S Haider T Kamal and M Ul-Islam ldquo(ermaldecomposition of metal complex precursor as route to thesynthesis of Co3O4 nanoparticles antibacterial activity andmechanismrdquo Journal of Alloys and Compounds vol 704pp 296ndash302 2017
[43] E M M Ibrahim L H Abdel-Rahman A M Abu-DiefA Elshafaie S K Hamdan and A M Ahmed ldquo(e synthesisof CuO andNiO nanoparticles by facile thermal decompositionof metal-Schiff base complexes and an examination of theirelectric thermoelectric and magnetic Propertiesrdquo MaterialsResearch Bulletin vol 107 pp 492ndash497 2018
[44] S Farhadi M Javanmard and G Nadri ldquoCharacterization ofcobalt oxide nanoparticles prepared by the thermal de-compositionrdquo Acta Chimica Slovenica vol 63 pp 335ndash3432016
[45] E M Zayed E H Ismail G G Mohamed M M H Khaliland A B Kamel ldquoSynthesis spectroscopic and structuralcharacterization and antimicrobial studies of metal com-plexes of a new hexadentate Schiff base ligand Spectropho-tometric determination of Fe(III) in water samples using arecovery testrdquo Monatshefte fur Chemie-Chemical Monthlyvol 145 no 5 pp 755ndash765 2014
[46] V Milacic D Chen L Ronconi K R Landis-PiwowarD Fregona and Q P Dou ldquoA novel anticancer gold(III)dithiocarbamate compound inhibits the activity of a purified20S proteasome and 26S proteasome in human breast cancercell cultures and xenograftsrdquo Cancer Research vol 66 no 21pp 10478ndash10486 2006
[47] T Mosmann ldquoRapid colorimetric assay for cellular growthand survival application to proliferation and cytotoxicityassaysrdquo Journal of Immunological Methods vol 65 no 1-2pp 55ndash63 1983
[48] R L Siegel K D Miller and A Jemal ldquoCancer statistics2018rdquo CA A Cancer Journal for Clinicians vol 68 no 1pp 7ndash30 2018
[49] S Chattopadhyay S P Chakraborty D Laha et al ldquoSurface-modified cobalt oxide nanoparticles new opportunities foranti-cancer drug developmentrdquo Cancer Nanotechnol vol 3no 1-6 pp 13ndash23 2012
[50] F Zielinski V Tognetti and L Joubert ldquoCondensed de-scriptors for reactivity a methodological studyrdquo ChemicalPhysics Letters vol 527 pp 67ndash72 2012
[51] H Wang Y He Q Yan et al ldquoCorrelation between thedielectric properties and biological activities of human ex vivohepatic tissuerdquo Physics in Medicine and Biology vol 60 no 6pp 2603ndash2617 2015
[52] F Tao F Fu F You et al ldquo(e correlation between dielectricproperties and microstructure of femoral bone in rats withdifferent bone qualitiesrdquo Annals of Biomedical Engineeringvol 42 no 6 pp 1238ndash1249 2014
[53] L Gun D Ning and Z Liang ldquoEffective permittivity ofbiological tissue comparison of theoretical model and ex-perimentrdquo Mathematical Problems in Engineering vol 2017Article ID 7249672 2017
[54] E I Ating S A Umoren I I Udousoro E E Ebenso andA P Udoh ldquoLeaves extract of Ananas sativumas greencorrosion inhibitor for aluminium in hydrochloric acid so-lutionsrdquo Green Chemistry Letters and Reviews vol 3 no 2pp 61ndash68 2010
[55] E Hamed ldquoStudies of the corrosion inhibition of copper inNa2SO4 solution using polarization and electrochemicalimpedance spectroscopyrdquo Materials Chemistry and Physicsvol 121 no 1-2 pp 70ndash76 2010
[56] H Zarrok H Oudda A Zarrouk et al ldquoWeight loss mea-surement and theoretical study of new pyridazine compoundas corrosion inhibitor for C38 steel in hydrochloric acidsolutionrdquo Der Pharma Chemica vol 3 no 6 pp 576ndash5902011
18 Journal of Chemistry
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Submit your manuscripts atwwwhindawicom
estimated using well-known DebyendashScherrer formula usingthe full width at half maximum (FWHM) of the (111) peaksin the XRD K(α) is the wavelength of X-ray source(15406 A 015406 nm) β∆θ is the full width at halfmaximum (FWHM 01378) and θ 387 is the diffractionangle corresponding to the lattice plane (111) which gives Dsim143ndash204plusmn 08 nm patterns [42ndash44]
(e pattern of XRD for cobalt oxide nanoparticles showscharacteristic peaks at 2θ values at 1898deg 3127deg 3682deg3848deg 4478deg 5568deg 5934deg 6521deg and 7731deg which arecorresponding to their indices (111) (220) (311) (400) (511)and (440) in agreement with JCPDS Card No 76ndash1802 (ispattern confirms the phase formation of cobalt oxidenanoparticle Figure 7(b) (e average size of the Co3O4particles was calculated by the DebyendashScherrer equationDK(α) λ(β cos θ) whereD is the average crystalline size λ isthe wavelength of CuKα θ is Braggrsquos angle and β is the fullwidth at half maximum (FWHM) of the diffraction peak (eaverage dimension D is sim147ndash182plusmn 06 nm at 2θ 3682degwhich is the intense peak [44]
332 EDX of Nano CuO (e synthesized nano copperoxide is confirmed by the EDX spectrum and SEM imagemeasurement shown in Figure 8 which confirms the highestformation percent of CuO and traces of copper carbide (eSEM image for nano copper oxide CuO shows a mixingnanosize 270sim1079 nm [42 43]
333 EDX of Nano Cobaltosic Oxide (e synthesized nanocobalt oxide is confirmed by the EDX spectrum measure-ment shown in Figure 9 which confirms the highest for-mation percent of cobaltosic oxide Co3O4 and traces ofcobalt carbide (e SEM image for nano cobaltosic oxideCo3O4 shows a mixing nanosize 318ndash8543 nm
34 Applications
341 Biological Activity Mixed ligand ternary complexeshave been examined for their in vitro antimicrobial activity(is investigation was performed using the diffusion agartechnique (Figure 5S) (e assays collection included
g-negative (Pseudomonas aeruginosa RCMB 010043 andEscherichia coli RCMB 010052) pathogenic bacteria usingGentamicin 5mgml as a reference compound and g-pos-itive (Streptococcus pneumoniae RCMB 010010 and Bacillissubtilis RCMB 010067) pathogenic bacteria using Ampi-cillin 5mgml as a reference compound It was also in-cluded four fungi (Aspergillus fumigatus RCMB 02568Syncephalastrum racemosum RCMB 05922 Geotrichumcandidum RCMB 05097 and Candida albicans RCMB05036) using Amphotericin B 5mgml as a referencecompound [30 45]
(e inhibitory effects of the used ligands and theirternary polymer complexes against the used organisms aregiven in Table 6 In general the used ligands did not displayantifungal or antibacterial inhibitory
For antifungal assay examination and based on theminimum inhibitory concentration (MIC) values it is foundthat the inhibitory effect of all the ternary complexes varyfrom moderate to weak against Amphotericin B controlexcept in the case of Candida albicans (RCMB 05036) whichis not affected by both cobalt and zinc complexes
(e antibacterial activities of the obtained ternarycomplexes are determined in terms of MIC values As shownin Table 6 all complexes display moderate activities againstStreptococcus pneumonia (RCMB 010010) and Bacillis sub-tilis RCMB 010067 (e growth of the gram-negative bac-teria Pseudomonas aeruginosa RCMB 010043 andEscherichia coli RCMB 010052 is extremely affected by bothcopper and nickel complexes which display strong inhibitionagainst the gram-negative pathogenic bacteria with MICvalue less than the Gentamicin control (e remainingcomplexes do not display the same behavior during theassay
342 Cytotoxicity One of the fundamental goals in me-dicinal chemistry is the development of new anticancer andantimicrobial therapeutic agents Cancer treatment usingmetal-based drugs is one of the very effective strategies as themetal ions are capable of binding to nucleic acids stereo-specifically with varying strength
In vitro anticancer activity evaluation of the newlysynthesized compounds was carried out against human
Cou
nts
400
300
200
100
010 20 30 40
Angles (deg2θ)50 60 70
(a)
Cou
nts
100
50
010 20 30 40
Angles (deg2θ)50 60 70
(b)
Figure 7 XRD pattern of (a) copper oxide CuO and (b) cobalt oxide Co3O4 prepared by thermal decomposition at 550Cdeg starting frommetal glutamic arginine mixed ligands complex
Journal of Chemistry 11
cancer cell lines hepatocellular carcinoma (HePG2) becauseliver cancer is the third most common cause of death incancer using MTT method [26 46 47]
Doxorubicin HCl is one of the most effective anti-cancer agents is used as a reference drug in this study (eobtained results from Table 2S indicated that most of thesemoleculesrsquo behavior can be observed from the values of the
half maximal inhibitory concentration IC50 whichfor glutamic and arginine are 167 and 376 μgmlrespectively
IC50 results indicate that the ternary complexes havepromised inhibition of HePG2 liver tumors [48 49]
Cell viability was assessed by themitochondrial-dependentreduction of yellow MTT (3-(45-dimethylthiazol-2-yl)-25-
108K096K084K072K060K048K036K024K012K000K
000 100 200 300 400 500 600 700 800 900
Cu Kβ
Cu Kα
Cu L
O KC K
(a) (b)
Figure 8 EDX and SEM images of CuO obtained by thermal decomposition at 550Cdeg starting from copper glutamic arginine mixed ligandscomplex
135K120K105K090K075K060K045K030K015K000K
000 100 200 300 400 500 600 700 800 900
O K
Co L Co Kα
Co Kβ
(a) (b)
Figure 9 EDX and SEM images of Co3O4 obtained by thermal decomposition at 550Cdeg starting from cobalt glutamic arginine mixedligands complex
Table 6 Antimicrobial activity of prepared ternary metal complexes
Sample tested microorganisms Glutamicacid L-arginine (1) (2) (3) (4) Standard
lowastNA no activity Values in bracket are the MIC values
12 Journal of Chemistry
diphenyl tetrazolium bromide) to insoluble purple formazan[45] (e prepared ternary metal complexes are of differentviability percentages as depicted in Figure 10 Data of bothligands are also included for comparison
Table 2S shows that the ligands have lower inhibition ofHePG2 than their metal ternary complexes (e coppercomplex introduces the highest inhibition
Additionally Table 7 summarizes some computedelectrical reactivity [50] and thermodynamic propertiesfor Co(II) and Cu(II) complexes (as maximum andminimum IC50 of the four prepared ternary metalscomplexes) which are correlated with the inhibition ofhuman cancer cells and are useful to explain the roleplayed by molecular properties in inhibition of humancancer cells
(e simulated data summarized in Table 7 conclude thefollowing
(i) Cu complex is more energetically stable relative toCo complex by about minus265 kJmol
(ii) Cu complex is characterized by lower dipole mo-ment and lower polarizability relative to Co(II)complexes
(iii) Enthalpy and Gibbs free energy of the Cu complexesare more stable by about minus265 kJmol relative toCo(II) complex Lower entropy reflects lower degreeof randomness of Cu(II) complex
(iv) (e chemical potential (μprime) (negative of molecularelectronegativity) of Cu(II) complex is much higherthan that of Co(II) complex reflecting the enhancedreactivity of Cu(II) complex as nucleophile becauseμprime measures the escaping tendency of electrons fromthe complex (μprime (LUMO+HOMO)2) [50]
(v) Cu complex is characterized by lower hardness thanCo(II) complex Hardness measures the resistanceto electron transfer (η (LUMO-HOMO)2) [50]
It seems that more thermodynamically stable and lesspolar Cu complex exhibits that enhanced responsive elec-tron cloud transfer to the surrounding tumor relative to theCo(II) complex (ese quantitative molecular descriptors[50] explain the promising inhibition activity of the Cu(II)complex (e results are correlated with the above-discussedPES results which show that Cu complex could act asnucleophile whereas Co complex is of enhanced electro-philic nature
(e nucleophilicity of Cu complex (seeking for positivelycharged sites of the reactant) together with its electricalthermodynamic and molecular properties favors its prom-ising inhibition activity towards HePG2 cancer cell [51ndash53]
343 Corrosion Inhibition of Aluminum An assessment ofcorrosion rates and inhibition efficiency for aluminum withdifferent inhibitor concentrations were computed as followscorrosion rate Rcorr was computed using equation (5)
Rcorr M1 minusM2( 1113857(mg)
A cm2( ) times t(h) (5)
where M1 weight (g) before immersion M2 weight (g)after immersion A area (cm2) of the specimen andt exposure time (h)
(e inhibition efficiency (IE) was evaluated usingequation (6)
IE Rblank minusRinh
Rblank1113890 1113891 times 100 (6)
120
60
100
80
60
40
20
00 10 20 30 40 50
GlutamicLarginineCu(II)
Ni(II)Co(II)Zn(II)
Figure 10 Cell viability of (HePG2) at different concentrations of ligands and the prepared metal complexes
Table 7 Simulated electrical properties of complexes studied exhibiting enhanced inhibition of HePG2
where Rblank corrosion rates in the absence of inhibitor andRinh corrosion rates in the presence of inhibitor [16]
Table 8 shows the calculated corrosion rates and inhibitionefficiencies of aluminum specimens in aqueous solution of 1MHCl as the corrosive medium in absence and presence ofmixed ligands and their ternary metal complexes at differenttemperatures (293 ndash313) K for 7 hours of each concentrationFigure 6S shows that as the concentration of ligands and theircomplexes increases Rcorr decreases and IE increases formixed ligands and their metal complexes acted as more ef-ficient inhibitors than their mixed ligands alone
344 Adsorption Isotherms and the +ermodynamic Acti-vation Parameters (e metal surface coverage degree(θIE100) was subjected to different adsorption iso-therms (e well fit for weight loss data is obtained forLangmuir adsorption isotherm Figure 11
Table 8 Corrosion parameters for aluminum in aqueous solution of 1M HCl in the absence and presence of different concentrations ofmixed ligands and their metal complexes at different temperatures for 7 hrs
Inhibitors C (times10minus2M)Corrosion rate times10minus4
Figure 11 Langmuir adsorption isotherms of the mixed ligands(L) and their metal complexes
14 Journal of Chemistry
(e temperature effect (293ndash313 K) on aluminum weightloss inhibition may be attributed to two main mechanismsphysical and chemical adsorption [37] (e suggested mech-anisms are obtained as the temperature increases the efficiencydecreases for mixed ligands but increases for their metalcomplexes depending on the nature of bond formation be-tween the mixed ligands and aluminum surface which isdifferent from the nature of bond formation between metalcomplexes and the aluminum surface [16] Arrhenius equation(7) gives the relation between the corrosion rate andtemperature
lnRcorr lnAminusElowast
RT (7)
where A is the Arrhenius factor Elowast is the apparent activationenergy of the corrosion process R is the rate gas constant andT is the absolute temperature (e straight line slope oflogRcorr vs 1T for aluminum 1M HCl at 4times10minus4molL after7 h is minusElowast2303R for the inhibitors (Figure 12)
(e activation thermodynamic parameters for alumi-num dissolution could be obtained from the transition stateequation (8)
lnRcorr
T1113874 1113875 ln
R
Nh1113874 1113875 +
ΔSlowast
R1113888 1113889minus
ΔHlowast
RT1113888 1113889 (8)
where the entropy of activation ∆Slowast and the apparent en-thalpy of activation ∆Hlowast can be obtained from the intercept
3150
02
04
06
logR
corr
(gmiddoth
ndash1middotcm
ndash1)
08
1
12
32 325 331000T(Kndash1)
335 34 345
BlankMix ligandsZn2+
Co2+Ni2+Cu2+
Figure 12 Arrhenius of log corrosion rate (Rcorr) vs 1T for aluminum in 1M HCl without and with 004times10minus2MLminus1 of inhibitors (mixedligands and their metal complexes)
Table 9 (ermodynamic parameters for the adsorption of (004times10minus2)ML mixed ligands and their metal complexes on aluminum metalin aqueous solution of 1M HCl at different temperatures for 7 hrs
and the slope for the straight line of the relation betweenln(RcorrT) vs (1T) respectively N is Avogadrorsquos numberand h is Planckrsquos constant (e Gibbs free energy of acti-vation ∆Glowast can be detected by equation (9)
ΔGlowast ΔHlowast minusTΔSlowast (9)
Table 9 shows the thermodynamic parameters for theadsorption of mixed ligands and their metal complexes (epositive value of ∆Hlowast indicated the endothermic property ofdissolution process nature for aluminum in the acidicmedium [54]
However the blank ΔHlowast value is higher than the in-hibitor metal complexes which indicated that the inhibitionefficiency generally increases with increasing temperature(e association step is the rate-determining step rather thana dissociation process in presence of the metal complexesinhibitors due to the negative values of ΔSlowast It is known thatthe values of ΔGlowast above 40 kJmiddotmolminus1 are referred to chargetransfer from the inhibitor molecules into aluminum surfaceto form coordinated compound on the Al surface whichblocks it against corrosion process by different degrees Alsothe chemical adsorption process mechanism is confirmed bythe values of ΔGlowast above 40 kJmiddotmolminus1 [16 54ndash56]
4 Conclusions
Novel coordination materials of ternary divalent metalions (Cu(II) Ni(II) Co(II) and Zn(II)) chelated by thebidentate glutamic acid (Glu) and L-arginine (Arg) aminoacids are synthesized and characterized (e metal ionscomplexes are modelled using density DFT and TD-DFTtheory Computed molecular and spectroscopic (IR UV-Vis and EPR) properties validated the experimental re-sults (e used computational methods are capable ofproviding good structural descriptions for the TM com-plexes Consistent with the experimental properties theoptimized structures of the complexes [Cu(II) Glu-Arg]and [Co(II) Glu-Arg (H2O)2] reveal that symmetry en-vironment of Cu(II) exhibits slightly distorted squareplanar shape whereas Co(II)-complex has a distortedoctahedral (where Co(II) central ion is of C4v-localsymmetry) Spectral properties of [Ni(II) Glu-Arg(H2O)2] and [ZnmiddotGlumiddotArgmiddot(H2O)2] complexes indicatethat they have similar structure as Co(II) complex All thestudied ternary metal complexes are of different anti-fungal activities ranging from moderate to weak withoutpractically noticed inhibitory effects whereas antibacte-rial activities of all studied metal complexes show sig-nificant effects
Cytotoxicity studies against (HePG2) reveal the prom-ising potentiality of Cu(II) complex as inhibitor of cancercells(e results are correlated with the computed moleculardescriptors including dipole moment polarizability ther-modynamics and reactivity properties as well as the PESmaps
(e corrosion inhibition of aluminum metal specimensin 1M HCl is efficiently achieved by mixed ligands and theirmetal complexes studied
Data Availability
(e data used to support the findings of this study areavailable from the corresponding author upon request
Conflicts of Interest
(e authors declare that they have no conflicts of interest
Supplementary Materials
(e supplementary materials consist of six figures and twotables to further clarify the structures and trends of the newlyprepared metal ternary complexes (SupplementaryMaterials)
References
[1] Z Ozturk D A Kose A Asan et al ldquoPorous metal-organicCu(II) complex of L-Arginine 2synthesis characterizationhydrogen storage properties and molecular simulation cal-culationsrdquo Hittite Journal of Science and Engineering vol 1no 1 pp 1ndash5 2014
[2] S A Lahsasni R A Ammar M F Amin et al ldquoMixed-ligandcomplex formation of Cu(II) with 12- diphenylethylenedi-amine as primary ligand and amino acids as secondary li-gandsrdquo International Journal of Electrochemical Sciencevol 7 pp 7699ndash7711 2012
[3] H Sigel B P Operschall S S Massoud B Song andR Griesser ldquoEvidence for intramolecular aromatic-ringstacking in the physiological pH range of the mono-deprotonated xanthine residue in mixed-ligand complexescontaining xanthosinate 5prime-monophosphate (XMP)rdquo DaltonTransactions vol 46 no 46 pp 5521ndash5529 2006
[4] S Udhayakumar K G Shankar S Sowndarya S VenkateshC Muralidharan and C Rose ldquol-Arginine intercedes bio-crosslinking of a collagen-chitosan 3D-hybrid scaffold fortissue engineering and regeneration in silico in vitro and invivo studiesrdquo RSC Advances vol 7 no 40 pp 25070ndash250882017
[5] P K Datta M Chandra and A K Dey ldquoTernary complexesof copper(II) nickel(II) and zinc(II) with nitrilotriacetic acidas a primary ligand and some phenolic acids as secondaryligandsrdquo Transition Metal Chemistry vol 5 no 1ndash3 1980
[6] J S Woertink L Tian D Maiti et al ldquoSpectroscopic andcomputational studies of an end-on bound superoxo-Cu(II)complex geometric and electronic factors that determine theground staterdquo Inorganic Chemistry vol 49 no 20pp 9450ndash9459 2010
[7] S Dutta S Ray K Nagarajan et al ldquoGlutamic acid analoguesused as potent anticancer a reviewrdquo Der Pharma Chemicavol 3 no 2 pp 263ndash272 2011
[8] T Sismanoglu S Pura and A Bastug ldquoBinary and ternarymetal complexes of Congo red with amino acidsrdquo Dyes andPigments vol 70 no 2 pp 136ndash142 2006
[9] R N Patel H C Pandey K B Pandeya et al ldquoMixed ligandcomplex formation of nickel(II)copper(II) and zinc(II) withsome amino acids and imidazolesrdquo Indian Journal ofChemistry-Section A Inorganic Physical +eoretical andAnalytical Chemistry vol 38 no 8 pp 850ndash853 1999
[10] L Meng and Z Lin ldquoComplexations of alkalialkaline earthmetal cations with gaseous glutamic acidrdquo Computational and+eoretical Chemistry vol 1039 pp 1ndash10 2014
16 Journal of Chemistry
[11] L D Pinto P A L Puppin V M Behring O C AlvesN A Rey and J Felcman ldquoSolution and solid state study ofcopper(II) ternary complexes containing amino acids of in-terest for brain biochemistry-2 homocysteine with aspartateglutamate or methioninerdquo Inorganica Chimica Acta vol 386pp 60ndash67 2012
[12] A Wojciechowska A Ggor and W Zierkiewicz ldquoChiraloctahedral complexes of Co(III) as catalysts for asymmetricepoxidation of chalcones under phase transfer conditionsrdquoRSC Advances vol 5 no 46 pp 36295ndash36306 2015
[13] B M Weckhuysen A A Verberckmoes L Fu andR A Schoonheydt ldquoZeolite-encapsulated copper(II) aminoacid complexes synthesis spectroscopy and catalysisrdquo Journalof Physical Chemistry vol 100 no 22 pp 9456ndash9461 1996
[14] K Y El-Baradie N A El-Wakiel and H A El-GhamryldquoSynthesis characterization and corrosion inhibition in acidmedium ofl-histidine Schiff base complexesrdquo Applied Or-ganometallic Chemistry vol 29 no 3 pp 117ndash125 2015
[15] S S R Anthony and R Susai ldquoInhibition of corrosion ofcarbon steel in well water by arginine-Zn2+ systemrdquo Journal ofElectrochemical Science and Engineering vol 2 no 2pp 91ndash104 2012
[16] E H Isamil F F AlBlewi N Soliman and M M H Khalilldquo(ermal studies and mass loss inhibition for some newmixed amino acid metal complexes with their applicationsrdquoJournal of +ermal Analysis and Calorimetry vol 125 no 1pp 289ndash300 2016
[17] F Neese ldquo(e ORCA program system 4012rdquo Wiley In-terdisciplinary Reviews Computational Molecular Sciencevol 2 no 1 pp 73ndash78 2012
[18] S Grimme S Ehrlich and L Goerigk ldquoEffect of the dampingfunction in dispersion corrected density functional theoryrdquoJournal of Computational Chemistry vol 32 no 7pp 1456ndash1465 2011
[19] S Grimme J Antony S Ehrlich and H Krieg ldquoA consistentand accurate ab initio parametrization of density functionaldispersion correction (DFT-D) for the 94 elements H-Purdquo+e Journal of Chemical Physics vol 132 no 15 article154104 2010
[20] F Weigend ldquoHartree-Fock exchange fitting basis sets for H toRnrdquo Journal of Computational Chemistry vol 29 no 2pp 167ndash175 2008
[21] F Neese F Wennmohs and A Hansen ldquoEfficient ap-proximate and parallel Hartree-Fock and hybrid DFT cal-culations A lsquochain-of-spheresrsquo algorithm for the Hartree-Fock exchangerdquo Chemical Physics vol 356 no 1ndash3pp 98ndash109 2009
[22] R Izsak and F Neese ldquoAn overlap fitted chain of spheresexchange methodrdquo Journal of Chemical Physics vol 135no 14 article 144105 2011
[23] T Petrenko S Kossmann and F Neese ldquoEfficient time-dependent density functional theory approximations forhybrid density functionals analytical gradients and paralle-lizationrdquo Journal of Chemical Physics vol 134 no 5 article054116 2011
[24] A V Marenich C J Cramer and D G Truhlar ldquoUniversalsolvation model based on solute electron density and on acontinuum model of the solvent defined by the bulk dielectricconstant and atomic surface tensionsrdquo Journal of PhysicalChemistry B vol 113 no 18 pp 6378ndash96 2009
[25] S Donovan C Stiefbold and K Sprague ldquoChapter 3Chemical properties of amino acids and identification ofunknown amino acidsrdquo in Proceedings of the 17 thWorkshopConference of the Association for Biology
Laboratory Education (ABLE) vol 17 pp 35ndash70 Bain-bridge GA USA March 1996
[26] C C Wagner J Enrique and C Claudia ldquoVibrational andmagnetic properties of a CuMg glutamate complexrdquoArgentina Acta Farm Bonaerense vol 22 no 2 pp 137ndash1422003
[27] M Arif R Sur and M Arshad ldquoStudies on the thermaldecomposition of copper (II) flouride complexes with variousamino acids in nitrogen atmosphererdquo Turkish Journal ofChemistry vol 25 pp 73ndash79 2001
[28] A Ghosh M J Tucker and R M Hochstrasser ldquoIdentifi-cation of arginine residues in peptides by 2d-IR echo spec-troscopyrdquo Journal of Physical Chemistry A vol 115 no 34pp 9731ndash9738 2011
[29] K Nakamoto Infrared Spectra of Inorganic and CoordinationCompounds Part B Wiley-Interscience New York NY USA5th edition 1997
[30] E Santi M H Torre E Kremer S B Etcheverry andE J Baran ldquoVibrational spectra of the copper(II) and nick-el(II) complexes of piroxicamrdquo Vibrational Spectroscopyvol 5 no 3 pp 285ndash293 1993
[31] H N Aliyu and A S Mohammed ldquoSynthesis spectropho-tometric and biological activity of nickel (II) and copper (II)complexes with schiff base derived from acetylacetone andhistidinerdquo Global Advanced Research Journal of Microbiologyvol 1 no 5 pp 67ndash71 2012
[32] J S Murray and P Politzer ldquo(e electrostatic potential anoverviewrdquo Wiley Interdisciplinary Reviews ComputationalMolecular Science vol 1 no 2 pp 153ndash163 2011
[33] E R Souaya M M H Khalil and E H Ismail ldquoSynthesis andcharacterization of ternary complexes of certain hydroxylacids and their biological applicationsrdquo Research Journal ofPharmaceutical Biological and Chemical Sciences vol 5 no 4pp 18ndash30 2014
[34] N N Greenwood and A Earnshaw A Review of Chemistry ofthe Elements Pergamon Press Oxford UK 1984
[35] V Reddy N Patil and S D Angadi ldquoSynthesis character-ization and antimicrobial activity of Cu(II) Co(II) and Ni(II)complexes with ON and S Donor ligandsrdquo E-Journal ofChemistry vol 5 no 3 pp 577ndash583 2008
[36] F A Cotton G Wilkinson C A Murillo et al Advances inSchiff Base Chemistry Wiley New York NY USA 6th edi-tion 1999
[37] M M H Khalil E H Ismail S A Azim and E R SouayaldquoSynthesis characterization and thermal analysis of ternarycomplexes of nitrilotriacetic acid and alanine or phenylala-nine with some transition metalsrdquo Journal of +ermalAnalysis and Calorimetry vol 101 no 1 pp 129ndash135 2010
[38] F Mabbs and D Colisson Electron Paramagnetic Resonanceof D Transition Metal Compounds Vol 102 ElsevierAmsterdam Netherlands 1992
[39] M M H Khalil E R Souaya E H Ismail et al ldquoTernarytransition metal complexes of nitrilotriacetic acid and valineor leucine synthesis and biological applicationsrdquo ChineseJournal of Inorganic Chemistry vol 29 no 9 pp 1969ndash19782013
[40] I M Weiss C Muth R Drumm and H O K Kirchnerldquo(ermal decomposition of the amino acids glycine cysteineaspartic acid asparagine glutamic acid glutamine arginineand histidinerdquo BMC Biophysics vol 11 no 1 2018
[41] A M Petrosyan V V Ghazaryan G Giester and M FleckldquoSulfamates and methanesulfonates of L-arginine and L-his-tidinerdquo Journal of Molecular Structure vol 1163 pp 114ndash1272018
Journal of Chemistry 17
[42] T Kavitha S Haider T Kamal and M Ul-Islam ldquo(ermaldecomposition of metal complex precursor as route to thesynthesis of Co3O4 nanoparticles antibacterial activity andmechanismrdquo Journal of Alloys and Compounds vol 704pp 296ndash302 2017
[43] E M M Ibrahim L H Abdel-Rahman A M Abu-DiefA Elshafaie S K Hamdan and A M Ahmed ldquo(e synthesisof CuO andNiO nanoparticles by facile thermal decompositionof metal-Schiff base complexes and an examination of theirelectric thermoelectric and magnetic Propertiesrdquo MaterialsResearch Bulletin vol 107 pp 492ndash497 2018
[44] S Farhadi M Javanmard and G Nadri ldquoCharacterization ofcobalt oxide nanoparticles prepared by the thermal de-compositionrdquo Acta Chimica Slovenica vol 63 pp 335ndash3432016
[45] E M Zayed E H Ismail G G Mohamed M M H Khaliland A B Kamel ldquoSynthesis spectroscopic and structuralcharacterization and antimicrobial studies of metal com-plexes of a new hexadentate Schiff base ligand Spectropho-tometric determination of Fe(III) in water samples using arecovery testrdquo Monatshefte fur Chemie-Chemical Monthlyvol 145 no 5 pp 755ndash765 2014
[46] V Milacic D Chen L Ronconi K R Landis-PiwowarD Fregona and Q P Dou ldquoA novel anticancer gold(III)dithiocarbamate compound inhibits the activity of a purified20S proteasome and 26S proteasome in human breast cancercell cultures and xenograftsrdquo Cancer Research vol 66 no 21pp 10478ndash10486 2006
[47] T Mosmann ldquoRapid colorimetric assay for cellular growthand survival application to proliferation and cytotoxicityassaysrdquo Journal of Immunological Methods vol 65 no 1-2pp 55ndash63 1983
[48] R L Siegel K D Miller and A Jemal ldquoCancer statistics2018rdquo CA A Cancer Journal for Clinicians vol 68 no 1pp 7ndash30 2018
[49] S Chattopadhyay S P Chakraborty D Laha et al ldquoSurface-modified cobalt oxide nanoparticles new opportunities foranti-cancer drug developmentrdquo Cancer Nanotechnol vol 3no 1-6 pp 13ndash23 2012
[50] F Zielinski V Tognetti and L Joubert ldquoCondensed de-scriptors for reactivity a methodological studyrdquo ChemicalPhysics Letters vol 527 pp 67ndash72 2012
[51] H Wang Y He Q Yan et al ldquoCorrelation between thedielectric properties and biological activities of human ex vivohepatic tissuerdquo Physics in Medicine and Biology vol 60 no 6pp 2603ndash2617 2015
[52] F Tao F Fu F You et al ldquo(e correlation between dielectricproperties and microstructure of femoral bone in rats withdifferent bone qualitiesrdquo Annals of Biomedical Engineeringvol 42 no 6 pp 1238ndash1249 2014
[53] L Gun D Ning and Z Liang ldquoEffective permittivity ofbiological tissue comparison of theoretical model and ex-perimentrdquo Mathematical Problems in Engineering vol 2017Article ID 7249672 2017
[54] E I Ating S A Umoren I I Udousoro E E Ebenso andA P Udoh ldquoLeaves extract of Ananas sativumas greencorrosion inhibitor for aluminium in hydrochloric acid so-lutionsrdquo Green Chemistry Letters and Reviews vol 3 no 2pp 61ndash68 2010
[55] E Hamed ldquoStudies of the corrosion inhibition of copper inNa2SO4 solution using polarization and electrochemicalimpedance spectroscopyrdquo Materials Chemistry and Physicsvol 121 no 1-2 pp 70ndash76 2010
[56] H Zarrok H Oudda A Zarrouk et al ldquoWeight loss mea-surement and theoretical study of new pyridazine compoundas corrosion inhibitor for C38 steel in hydrochloric acidsolutionrdquo Der Pharma Chemica vol 3 no 6 pp 576ndash5902011
18 Journal of Chemistry
TribologyAdvances in
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
International Journal ofInternational Journal ofPhotoenergy
Hindawiwwwhindawicom Volume 2018
Journal of
Chemistry
Hindawiwwwhindawicom Volume 2018
Advances inPhysical Chemistry
Hindawiwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2018
Bioinorganic Chemistry and ApplicationsHindawiwwwhindawicom Volume 2018
SpectroscopyAnalytical ChemistryInternational Journal of
Hindawiwwwhindawicom Volume 2018
MaterialsJournal of
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
BioMed Research International Electrochemistry
International Journal of
Hindawiwwwhindawicom Volume 2018
Na
nom
ate
ria
ls
Hindawiwwwhindawicom Volume 2018
Journal ofNanomaterials
Submit your manuscripts atwwwhindawicom
cancer cell lines hepatocellular carcinoma (HePG2) becauseliver cancer is the third most common cause of death incancer using MTT method [26 46 47]
Doxorubicin HCl is one of the most effective anti-cancer agents is used as a reference drug in this study (eobtained results from Table 2S indicated that most of thesemoleculesrsquo behavior can be observed from the values of the
half maximal inhibitory concentration IC50 whichfor glutamic and arginine are 167 and 376 μgmlrespectively
IC50 results indicate that the ternary complexes havepromised inhibition of HePG2 liver tumors [48 49]
Cell viability was assessed by themitochondrial-dependentreduction of yellow MTT (3-(45-dimethylthiazol-2-yl)-25-
108K096K084K072K060K048K036K024K012K000K
000 100 200 300 400 500 600 700 800 900
Cu Kβ
Cu Kα
Cu L
O KC K
(a) (b)
Figure 8 EDX and SEM images of CuO obtained by thermal decomposition at 550Cdeg starting from copper glutamic arginine mixed ligandscomplex
135K120K105K090K075K060K045K030K015K000K
000 100 200 300 400 500 600 700 800 900
O K
Co L Co Kα
Co Kβ
(a) (b)
Figure 9 EDX and SEM images of Co3O4 obtained by thermal decomposition at 550Cdeg starting from cobalt glutamic arginine mixedligands complex
Table 6 Antimicrobial activity of prepared ternary metal complexes
Sample tested microorganisms Glutamicacid L-arginine (1) (2) (3) (4) Standard
lowastNA no activity Values in bracket are the MIC values
12 Journal of Chemistry
diphenyl tetrazolium bromide) to insoluble purple formazan[45] (e prepared ternary metal complexes are of differentviability percentages as depicted in Figure 10 Data of bothligands are also included for comparison
Table 2S shows that the ligands have lower inhibition ofHePG2 than their metal ternary complexes (e coppercomplex introduces the highest inhibition
Additionally Table 7 summarizes some computedelectrical reactivity [50] and thermodynamic propertiesfor Co(II) and Cu(II) complexes (as maximum andminimum IC50 of the four prepared ternary metalscomplexes) which are correlated with the inhibition ofhuman cancer cells and are useful to explain the roleplayed by molecular properties in inhibition of humancancer cells
(e simulated data summarized in Table 7 conclude thefollowing
(i) Cu complex is more energetically stable relative toCo complex by about minus265 kJmol
(ii) Cu complex is characterized by lower dipole mo-ment and lower polarizability relative to Co(II)complexes
(iii) Enthalpy and Gibbs free energy of the Cu complexesare more stable by about minus265 kJmol relative toCo(II) complex Lower entropy reflects lower degreeof randomness of Cu(II) complex
(iv) (e chemical potential (μprime) (negative of molecularelectronegativity) of Cu(II) complex is much higherthan that of Co(II) complex reflecting the enhancedreactivity of Cu(II) complex as nucleophile becauseμprime measures the escaping tendency of electrons fromthe complex (μprime (LUMO+HOMO)2) [50]
(v) Cu complex is characterized by lower hardness thanCo(II) complex Hardness measures the resistanceto electron transfer (η (LUMO-HOMO)2) [50]
It seems that more thermodynamically stable and lesspolar Cu complex exhibits that enhanced responsive elec-tron cloud transfer to the surrounding tumor relative to theCo(II) complex (ese quantitative molecular descriptors[50] explain the promising inhibition activity of the Cu(II)complex (e results are correlated with the above-discussedPES results which show that Cu complex could act asnucleophile whereas Co complex is of enhanced electro-philic nature
(e nucleophilicity of Cu complex (seeking for positivelycharged sites of the reactant) together with its electricalthermodynamic and molecular properties favors its prom-ising inhibition activity towards HePG2 cancer cell [51ndash53]
343 Corrosion Inhibition of Aluminum An assessment ofcorrosion rates and inhibition efficiency for aluminum withdifferent inhibitor concentrations were computed as followscorrosion rate Rcorr was computed using equation (5)
Rcorr M1 minusM2( 1113857(mg)
A cm2( ) times t(h) (5)
where M1 weight (g) before immersion M2 weight (g)after immersion A area (cm2) of the specimen andt exposure time (h)
(e inhibition efficiency (IE) was evaluated usingequation (6)
IE Rblank minusRinh
Rblank1113890 1113891 times 100 (6)
120
60
100
80
60
40
20
00 10 20 30 40 50
GlutamicLarginineCu(II)
Ni(II)Co(II)Zn(II)
Figure 10 Cell viability of (HePG2) at different concentrations of ligands and the prepared metal complexes
Table 7 Simulated electrical properties of complexes studied exhibiting enhanced inhibition of HePG2
where Rblank corrosion rates in the absence of inhibitor andRinh corrosion rates in the presence of inhibitor [16]
Table 8 shows the calculated corrosion rates and inhibitionefficiencies of aluminum specimens in aqueous solution of 1MHCl as the corrosive medium in absence and presence ofmixed ligands and their ternary metal complexes at differenttemperatures (293 ndash313) K for 7 hours of each concentrationFigure 6S shows that as the concentration of ligands and theircomplexes increases Rcorr decreases and IE increases formixed ligands and their metal complexes acted as more ef-ficient inhibitors than their mixed ligands alone
344 Adsorption Isotherms and the +ermodynamic Acti-vation Parameters (e metal surface coverage degree(θIE100) was subjected to different adsorption iso-therms (e well fit for weight loss data is obtained forLangmuir adsorption isotherm Figure 11
Table 8 Corrosion parameters for aluminum in aqueous solution of 1M HCl in the absence and presence of different concentrations ofmixed ligands and their metal complexes at different temperatures for 7 hrs
Inhibitors C (times10minus2M)Corrosion rate times10minus4
Figure 11 Langmuir adsorption isotherms of the mixed ligands(L) and their metal complexes
14 Journal of Chemistry
(e temperature effect (293ndash313 K) on aluminum weightloss inhibition may be attributed to two main mechanismsphysical and chemical adsorption [37] (e suggested mech-anisms are obtained as the temperature increases the efficiencydecreases for mixed ligands but increases for their metalcomplexes depending on the nature of bond formation be-tween the mixed ligands and aluminum surface which isdifferent from the nature of bond formation between metalcomplexes and the aluminum surface [16] Arrhenius equation(7) gives the relation between the corrosion rate andtemperature
lnRcorr lnAminusElowast
RT (7)
where A is the Arrhenius factor Elowast is the apparent activationenergy of the corrosion process R is the rate gas constant andT is the absolute temperature (e straight line slope oflogRcorr vs 1T for aluminum 1M HCl at 4times10minus4molL after7 h is minusElowast2303R for the inhibitors (Figure 12)
(e activation thermodynamic parameters for alumi-num dissolution could be obtained from the transition stateequation (8)
lnRcorr
T1113874 1113875 ln
R
Nh1113874 1113875 +
ΔSlowast
R1113888 1113889minus
ΔHlowast
RT1113888 1113889 (8)
where the entropy of activation ∆Slowast and the apparent en-thalpy of activation ∆Hlowast can be obtained from the intercept
3150
02
04
06
logR
corr
(gmiddoth
ndash1middotcm
ndash1)
08
1
12
32 325 331000T(Kndash1)
335 34 345
BlankMix ligandsZn2+
Co2+Ni2+Cu2+
Figure 12 Arrhenius of log corrosion rate (Rcorr) vs 1T for aluminum in 1M HCl without and with 004times10minus2MLminus1 of inhibitors (mixedligands and their metal complexes)
Table 9 (ermodynamic parameters for the adsorption of (004times10minus2)ML mixed ligands and their metal complexes on aluminum metalin aqueous solution of 1M HCl at different temperatures for 7 hrs
and the slope for the straight line of the relation betweenln(RcorrT) vs (1T) respectively N is Avogadrorsquos numberand h is Planckrsquos constant (e Gibbs free energy of acti-vation ∆Glowast can be detected by equation (9)
ΔGlowast ΔHlowast minusTΔSlowast (9)
Table 9 shows the thermodynamic parameters for theadsorption of mixed ligands and their metal complexes (epositive value of ∆Hlowast indicated the endothermic property ofdissolution process nature for aluminum in the acidicmedium [54]
However the blank ΔHlowast value is higher than the in-hibitor metal complexes which indicated that the inhibitionefficiency generally increases with increasing temperature(e association step is the rate-determining step rather thana dissociation process in presence of the metal complexesinhibitors due to the negative values of ΔSlowast It is known thatthe values of ΔGlowast above 40 kJmiddotmolminus1 are referred to chargetransfer from the inhibitor molecules into aluminum surfaceto form coordinated compound on the Al surface whichblocks it against corrosion process by different degrees Alsothe chemical adsorption process mechanism is confirmed bythe values of ΔGlowast above 40 kJmiddotmolminus1 [16 54ndash56]
4 Conclusions
Novel coordination materials of ternary divalent metalions (Cu(II) Ni(II) Co(II) and Zn(II)) chelated by thebidentate glutamic acid (Glu) and L-arginine (Arg) aminoacids are synthesized and characterized (e metal ionscomplexes are modelled using density DFT and TD-DFTtheory Computed molecular and spectroscopic (IR UV-Vis and EPR) properties validated the experimental re-sults (e used computational methods are capable ofproviding good structural descriptions for the TM com-plexes Consistent with the experimental properties theoptimized structures of the complexes [Cu(II) Glu-Arg]and [Co(II) Glu-Arg (H2O)2] reveal that symmetry en-vironment of Cu(II) exhibits slightly distorted squareplanar shape whereas Co(II)-complex has a distortedoctahedral (where Co(II) central ion is of C4v-localsymmetry) Spectral properties of [Ni(II) Glu-Arg(H2O)2] and [ZnmiddotGlumiddotArgmiddot(H2O)2] complexes indicatethat they have similar structure as Co(II) complex All thestudied ternary metal complexes are of different anti-fungal activities ranging from moderate to weak withoutpractically noticed inhibitory effects whereas antibacte-rial activities of all studied metal complexes show sig-nificant effects
Cytotoxicity studies against (HePG2) reveal the prom-ising potentiality of Cu(II) complex as inhibitor of cancercells(e results are correlated with the computed moleculardescriptors including dipole moment polarizability ther-modynamics and reactivity properties as well as the PESmaps
(e corrosion inhibition of aluminum metal specimensin 1M HCl is efficiently achieved by mixed ligands and theirmetal complexes studied
Data Availability
(e data used to support the findings of this study areavailable from the corresponding author upon request
Conflicts of Interest
(e authors declare that they have no conflicts of interest
Supplementary Materials
(e supplementary materials consist of six figures and twotables to further clarify the structures and trends of the newlyprepared metal ternary complexes (SupplementaryMaterials)
References
[1] Z Ozturk D A Kose A Asan et al ldquoPorous metal-organicCu(II) complex of L-Arginine 2synthesis characterizationhydrogen storage properties and molecular simulation cal-culationsrdquo Hittite Journal of Science and Engineering vol 1no 1 pp 1ndash5 2014
[2] S A Lahsasni R A Ammar M F Amin et al ldquoMixed-ligandcomplex formation of Cu(II) with 12- diphenylethylenedi-amine as primary ligand and amino acids as secondary li-gandsrdquo International Journal of Electrochemical Sciencevol 7 pp 7699ndash7711 2012
[3] H Sigel B P Operschall S S Massoud B Song andR Griesser ldquoEvidence for intramolecular aromatic-ringstacking in the physiological pH range of the mono-deprotonated xanthine residue in mixed-ligand complexescontaining xanthosinate 5prime-monophosphate (XMP)rdquo DaltonTransactions vol 46 no 46 pp 5521ndash5529 2006
[4] S Udhayakumar K G Shankar S Sowndarya S VenkateshC Muralidharan and C Rose ldquol-Arginine intercedes bio-crosslinking of a collagen-chitosan 3D-hybrid scaffold fortissue engineering and regeneration in silico in vitro and invivo studiesrdquo RSC Advances vol 7 no 40 pp 25070ndash250882017
[5] P K Datta M Chandra and A K Dey ldquoTernary complexesof copper(II) nickel(II) and zinc(II) with nitrilotriacetic acidas a primary ligand and some phenolic acids as secondaryligandsrdquo Transition Metal Chemistry vol 5 no 1ndash3 1980
[6] J S Woertink L Tian D Maiti et al ldquoSpectroscopic andcomputational studies of an end-on bound superoxo-Cu(II)complex geometric and electronic factors that determine theground staterdquo Inorganic Chemistry vol 49 no 20pp 9450ndash9459 2010
[7] S Dutta S Ray K Nagarajan et al ldquoGlutamic acid analoguesused as potent anticancer a reviewrdquo Der Pharma Chemicavol 3 no 2 pp 263ndash272 2011
[8] T Sismanoglu S Pura and A Bastug ldquoBinary and ternarymetal complexes of Congo red with amino acidsrdquo Dyes andPigments vol 70 no 2 pp 136ndash142 2006
[9] R N Patel H C Pandey K B Pandeya et al ldquoMixed ligandcomplex formation of nickel(II)copper(II) and zinc(II) withsome amino acids and imidazolesrdquo Indian Journal ofChemistry-Section A Inorganic Physical +eoretical andAnalytical Chemistry vol 38 no 8 pp 850ndash853 1999
[10] L Meng and Z Lin ldquoComplexations of alkalialkaline earthmetal cations with gaseous glutamic acidrdquo Computational and+eoretical Chemistry vol 1039 pp 1ndash10 2014
16 Journal of Chemistry
[11] L D Pinto P A L Puppin V M Behring O C AlvesN A Rey and J Felcman ldquoSolution and solid state study ofcopper(II) ternary complexes containing amino acids of in-terest for brain biochemistry-2 homocysteine with aspartateglutamate or methioninerdquo Inorganica Chimica Acta vol 386pp 60ndash67 2012
[12] A Wojciechowska A Ggor and W Zierkiewicz ldquoChiraloctahedral complexes of Co(III) as catalysts for asymmetricepoxidation of chalcones under phase transfer conditionsrdquoRSC Advances vol 5 no 46 pp 36295ndash36306 2015
[13] B M Weckhuysen A A Verberckmoes L Fu andR A Schoonheydt ldquoZeolite-encapsulated copper(II) aminoacid complexes synthesis spectroscopy and catalysisrdquo Journalof Physical Chemistry vol 100 no 22 pp 9456ndash9461 1996
[14] K Y El-Baradie N A El-Wakiel and H A El-GhamryldquoSynthesis characterization and corrosion inhibition in acidmedium ofl-histidine Schiff base complexesrdquo Applied Or-ganometallic Chemistry vol 29 no 3 pp 117ndash125 2015
[15] S S R Anthony and R Susai ldquoInhibition of corrosion ofcarbon steel in well water by arginine-Zn2+ systemrdquo Journal ofElectrochemical Science and Engineering vol 2 no 2pp 91ndash104 2012
[16] E H Isamil F F AlBlewi N Soliman and M M H Khalilldquo(ermal studies and mass loss inhibition for some newmixed amino acid metal complexes with their applicationsrdquoJournal of +ermal Analysis and Calorimetry vol 125 no 1pp 289ndash300 2016
[17] F Neese ldquo(e ORCA program system 4012rdquo Wiley In-terdisciplinary Reviews Computational Molecular Sciencevol 2 no 1 pp 73ndash78 2012
[18] S Grimme S Ehrlich and L Goerigk ldquoEffect of the dampingfunction in dispersion corrected density functional theoryrdquoJournal of Computational Chemistry vol 32 no 7pp 1456ndash1465 2011
[19] S Grimme J Antony S Ehrlich and H Krieg ldquoA consistentand accurate ab initio parametrization of density functionaldispersion correction (DFT-D) for the 94 elements H-Purdquo+e Journal of Chemical Physics vol 132 no 15 article154104 2010
[20] F Weigend ldquoHartree-Fock exchange fitting basis sets for H toRnrdquo Journal of Computational Chemistry vol 29 no 2pp 167ndash175 2008
[21] F Neese F Wennmohs and A Hansen ldquoEfficient ap-proximate and parallel Hartree-Fock and hybrid DFT cal-culations A lsquochain-of-spheresrsquo algorithm for the Hartree-Fock exchangerdquo Chemical Physics vol 356 no 1ndash3pp 98ndash109 2009
[22] R Izsak and F Neese ldquoAn overlap fitted chain of spheresexchange methodrdquo Journal of Chemical Physics vol 135no 14 article 144105 2011
[23] T Petrenko S Kossmann and F Neese ldquoEfficient time-dependent density functional theory approximations forhybrid density functionals analytical gradients and paralle-lizationrdquo Journal of Chemical Physics vol 134 no 5 article054116 2011
[24] A V Marenich C J Cramer and D G Truhlar ldquoUniversalsolvation model based on solute electron density and on acontinuum model of the solvent defined by the bulk dielectricconstant and atomic surface tensionsrdquo Journal of PhysicalChemistry B vol 113 no 18 pp 6378ndash96 2009
[25] S Donovan C Stiefbold and K Sprague ldquoChapter 3Chemical properties of amino acids and identification ofunknown amino acidsrdquo in Proceedings of the 17 thWorkshopConference of the Association for Biology
Laboratory Education (ABLE) vol 17 pp 35ndash70 Bain-bridge GA USA March 1996
[26] C C Wagner J Enrique and C Claudia ldquoVibrational andmagnetic properties of a CuMg glutamate complexrdquoArgentina Acta Farm Bonaerense vol 22 no 2 pp 137ndash1422003
[27] M Arif R Sur and M Arshad ldquoStudies on the thermaldecomposition of copper (II) flouride complexes with variousamino acids in nitrogen atmosphererdquo Turkish Journal ofChemistry vol 25 pp 73ndash79 2001
[28] A Ghosh M J Tucker and R M Hochstrasser ldquoIdentifi-cation of arginine residues in peptides by 2d-IR echo spec-troscopyrdquo Journal of Physical Chemistry A vol 115 no 34pp 9731ndash9738 2011
[29] K Nakamoto Infrared Spectra of Inorganic and CoordinationCompounds Part B Wiley-Interscience New York NY USA5th edition 1997
[30] E Santi M H Torre E Kremer S B Etcheverry andE J Baran ldquoVibrational spectra of the copper(II) and nick-el(II) complexes of piroxicamrdquo Vibrational Spectroscopyvol 5 no 3 pp 285ndash293 1993
[31] H N Aliyu and A S Mohammed ldquoSynthesis spectropho-tometric and biological activity of nickel (II) and copper (II)complexes with schiff base derived from acetylacetone andhistidinerdquo Global Advanced Research Journal of Microbiologyvol 1 no 5 pp 67ndash71 2012
[32] J S Murray and P Politzer ldquo(e electrostatic potential anoverviewrdquo Wiley Interdisciplinary Reviews ComputationalMolecular Science vol 1 no 2 pp 153ndash163 2011
[33] E R Souaya M M H Khalil and E H Ismail ldquoSynthesis andcharacterization of ternary complexes of certain hydroxylacids and their biological applicationsrdquo Research Journal ofPharmaceutical Biological and Chemical Sciences vol 5 no 4pp 18ndash30 2014
[34] N N Greenwood and A Earnshaw A Review of Chemistry ofthe Elements Pergamon Press Oxford UK 1984
[35] V Reddy N Patil and S D Angadi ldquoSynthesis character-ization and antimicrobial activity of Cu(II) Co(II) and Ni(II)complexes with ON and S Donor ligandsrdquo E-Journal ofChemistry vol 5 no 3 pp 577ndash583 2008
[36] F A Cotton G Wilkinson C A Murillo et al Advances inSchiff Base Chemistry Wiley New York NY USA 6th edi-tion 1999
[37] M M H Khalil E H Ismail S A Azim and E R SouayaldquoSynthesis characterization and thermal analysis of ternarycomplexes of nitrilotriacetic acid and alanine or phenylala-nine with some transition metalsrdquo Journal of +ermalAnalysis and Calorimetry vol 101 no 1 pp 129ndash135 2010
[38] F Mabbs and D Colisson Electron Paramagnetic Resonanceof D Transition Metal Compounds Vol 102 ElsevierAmsterdam Netherlands 1992
[39] M M H Khalil E R Souaya E H Ismail et al ldquoTernarytransition metal complexes of nitrilotriacetic acid and valineor leucine synthesis and biological applicationsrdquo ChineseJournal of Inorganic Chemistry vol 29 no 9 pp 1969ndash19782013
[40] I M Weiss C Muth R Drumm and H O K Kirchnerldquo(ermal decomposition of the amino acids glycine cysteineaspartic acid asparagine glutamic acid glutamine arginineand histidinerdquo BMC Biophysics vol 11 no 1 2018
[41] A M Petrosyan V V Ghazaryan G Giester and M FleckldquoSulfamates and methanesulfonates of L-arginine and L-his-tidinerdquo Journal of Molecular Structure vol 1163 pp 114ndash1272018
Journal of Chemistry 17
[42] T Kavitha S Haider T Kamal and M Ul-Islam ldquo(ermaldecomposition of metal complex precursor as route to thesynthesis of Co3O4 nanoparticles antibacterial activity andmechanismrdquo Journal of Alloys and Compounds vol 704pp 296ndash302 2017
[43] E M M Ibrahim L H Abdel-Rahman A M Abu-DiefA Elshafaie S K Hamdan and A M Ahmed ldquo(e synthesisof CuO andNiO nanoparticles by facile thermal decompositionof metal-Schiff base complexes and an examination of theirelectric thermoelectric and magnetic Propertiesrdquo MaterialsResearch Bulletin vol 107 pp 492ndash497 2018
[44] S Farhadi M Javanmard and G Nadri ldquoCharacterization ofcobalt oxide nanoparticles prepared by the thermal de-compositionrdquo Acta Chimica Slovenica vol 63 pp 335ndash3432016
[45] E M Zayed E H Ismail G G Mohamed M M H Khaliland A B Kamel ldquoSynthesis spectroscopic and structuralcharacterization and antimicrobial studies of metal com-plexes of a new hexadentate Schiff base ligand Spectropho-tometric determination of Fe(III) in water samples using arecovery testrdquo Monatshefte fur Chemie-Chemical Monthlyvol 145 no 5 pp 755ndash765 2014
[46] V Milacic D Chen L Ronconi K R Landis-PiwowarD Fregona and Q P Dou ldquoA novel anticancer gold(III)dithiocarbamate compound inhibits the activity of a purified20S proteasome and 26S proteasome in human breast cancercell cultures and xenograftsrdquo Cancer Research vol 66 no 21pp 10478ndash10486 2006
[47] T Mosmann ldquoRapid colorimetric assay for cellular growthand survival application to proliferation and cytotoxicityassaysrdquo Journal of Immunological Methods vol 65 no 1-2pp 55ndash63 1983
[48] R L Siegel K D Miller and A Jemal ldquoCancer statistics2018rdquo CA A Cancer Journal for Clinicians vol 68 no 1pp 7ndash30 2018
[49] S Chattopadhyay S P Chakraborty D Laha et al ldquoSurface-modified cobalt oxide nanoparticles new opportunities foranti-cancer drug developmentrdquo Cancer Nanotechnol vol 3no 1-6 pp 13ndash23 2012
[50] F Zielinski V Tognetti and L Joubert ldquoCondensed de-scriptors for reactivity a methodological studyrdquo ChemicalPhysics Letters vol 527 pp 67ndash72 2012
[51] H Wang Y He Q Yan et al ldquoCorrelation between thedielectric properties and biological activities of human ex vivohepatic tissuerdquo Physics in Medicine and Biology vol 60 no 6pp 2603ndash2617 2015
[52] F Tao F Fu F You et al ldquo(e correlation between dielectricproperties and microstructure of femoral bone in rats withdifferent bone qualitiesrdquo Annals of Biomedical Engineeringvol 42 no 6 pp 1238ndash1249 2014
[53] L Gun D Ning and Z Liang ldquoEffective permittivity ofbiological tissue comparison of theoretical model and ex-perimentrdquo Mathematical Problems in Engineering vol 2017Article ID 7249672 2017
[54] E I Ating S A Umoren I I Udousoro E E Ebenso andA P Udoh ldquoLeaves extract of Ananas sativumas greencorrosion inhibitor for aluminium in hydrochloric acid so-lutionsrdquo Green Chemistry Letters and Reviews vol 3 no 2pp 61ndash68 2010
[55] E Hamed ldquoStudies of the corrosion inhibition of copper inNa2SO4 solution using polarization and electrochemicalimpedance spectroscopyrdquo Materials Chemistry and Physicsvol 121 no 1-2 pp 70ndash76 2010
[56] H Zarrok H Oudda A Zarrouk et al ldquoWeight loss mea-surement and theoretical study of new pyridazine compoundas corrosion inhibitor for C38 steel in hydrochloric acidsolutionrdquo Der Pharma Chemica vol 3 no 6 pp 576ndash5902011
18 Journal of Chemistry
TribologyAdvances in
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
International Journal ofInternational Journal ofPhotoenergy
Hindawiwwwhindawicom Volume 2018
Journal of
Chemistry
Hindawiwwwhindawicom Volume 2018
Advances inPhysical Chemistry
Hindawiwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2018
Bioinorganic Chemistry and ApplicationsHindawiwwwhindawicom Volume 2018
SpectroscopyAnalytical ChemistryInternational Journal of
Hindawiwwwhindawicom Volume 2018
MaterialsJournal of
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
BioMed Research International Electrochemistry
International Journal of
Hindawiwwwhindawicom Volume 2018
Na
nom
ate
ria
ls
Hindawiwwwhindawicom Volume 2018
Journal ofNanomaterials
Submit your manuscripts atwwwhindawicom
diphenyl tetrazolium bromide) to insoluble purple formazan[45] (e prepared ternary metal complexes are of differentviability percentages as depicted in Figure 10 Data of bothligands are also included for comparison
Table 2S shows that the ligands have lower inhibition ofHePG2 than their metal ternary complexes (e coppercomplex introduces the highest inhibition
Additionally Table 7 summarizes some computedelectrical reactivity [50] and thermodynamic propertiesfor Co(II) and Cu(II) complexes (as maximum andminimum IC50 of the four prepared ternary metalscomplexes) which are correlated with the inhibition ofhuman cancer cells and are useful to explain the roleplayed by molecular properties in inhibition of humancancer cells
(e simulated data summarized in Table 7 conclude thefollowing
(i) Cu complex is more energetically stable relative toCo complex by about minus265 kJmol
(ii) Cu complex is characterized by lower dipole mo-ment and lower polarizability relative to Co(II)complexes
(iii) Enthalpy and Gibbs free energy of the Cu complexesare more stable by about minus265 kJmol relative toCo(II) complex Lower entropy reflects lower degreeof randomness of Cu(II) complex
(iv) (e chemical potential (μprime) (negative of molecularelectronegativity) of Cu(II) complex is much higherthan that of Co(II) complex reflecting the enhancedreactivity of Cu(II) complex as nucleophile becauseμprime measures the escaping tendency of electrons fromthe complex (μprime (LUMO+HOMO)2) [50]
(v) Cu complex is characterized by lower hardness thanCo(II) complex Hardness measures the resistanceto electron transfer (η (LUMO-HOMO)2) [50]
It seems that more thermodynamically stable and lesspolar Cu complex exhibits that enhanced responsive elec-tron cloud transfer to the surrounding tumor relative to theCo(II) complex (ese quantitative molecular descriptors[50] explain the promising inhibition activity of the Cu(II)complex (e results are correlated with the above-discussedPES results which show that Cu complex could act asnucleophile whereas Co complex is of enhanced electro-philic nature
(e nucleophilicity of Cu complex (seeking for positivelycharged sites of the reactant) together with its electricalthermodynamic and molecular properties favors its prom-ising inhibition activity towards HePG2 cancer cell [51ndash53]
343 Corrosion Inhibition of Aluminum An assessment ofcorrosion rates and inhibition efficiency for aluminum withdifferent inhibitor concentrations were computed as followscorrosion rate Rcorr was computed using equation (5)
Rcorr M1 minusM2( 1113857(mg)
A cm2( ) times t(h) (5)
where M1 weight (g) before immersion M2 weight (g)after immersion A area (cm2) of the specimen andt exposure time (h)
(e inhibition efficiency (IE) was evaluated usingequation (6)
IE Rblank minusRinh
Rblank1113890 1113891 times 100 (6)
120
60
100
80
60
40
20
00 10 20 30 40 50
GlutamicLarginineCu(II)
Ni(II)Co(II)Zn(II)
Figure 10 Cell viability of (HePG2) at different concentrations of ligands and the prepared metal complexes
Table 7 Simulated electrical properties of complexes studied exhibiting enhanced inhibition of HePG2
where Rblank corrosion rates in the absence of inhibitor andRinh corrosion rates in the presence of inhibitor [16]
Table 8 shows the calculated corrosion rates and inhibitionefficiencies of aluminum specimens in aqueous solution of 1MHCl as the corrosive medium in absence and presence ofmixed ligands and their ternary metal complexes at differenttemperatures (293 ndash313) K for 7 hours of each concentrationFigure 6S shows that as the concentration of ligands and theircomplexes increases Rcorr decreases and IE increases formixed ligands and their metal complexes acted as more ef-ficient inhibitors than their mixed ligands alone
344 Adsorption Isotherms and the +ermodynamic Acti-vation Parameters (e metal surface coverage degree(θIE100) was subjected to different adsorption iso-therms (e well fit for weight loss data is obtained forLangmuir adsorption isotherm Figure 11
Table 8 Corrosion parameters for aluminum in aqueous solution of 1M HCl in the absence and presence of different concentrations ofmixed ligands and their metal complexes at different temperatures for 7 hrs
Inhibitors C (times10minus2M)Corrosion rate times10minus4
Figure 11 Langmuir adsorption isotherms of the mixed ligands(L) and their metal complexes
14 Journal of Chemistry
(e temperature effect (293ndash313 K) on aluminum weightloss inhibition may be attributed to two main mechanismsphysical and chemical adsorption [37] (e suggested mech-anisms are obtained as the temperature increases the efficiencydecreases for mixed ligands but increases for their metalcomplexes depending on the nature of bond formation be-tween the mixed ligands and aluminum surface which isdifferent from the nature of bond formation between metalcomplexes and the aluminum surface [16] Arrhenius equation(7) gives the relation between the corrosion rate andtemperature
lnRcorr lnAminusElowast
RT (7)
where A is the Arrhenius factor Elowast is the apparent activationenergy of the corrosion process R is the rate gas constant andT is the absolute temperature (e straight line slope oflogRcorr vs 1T for aluminum 1M HCl at 4times10minus4molL after7 h is minusElowast2303R for the inhibitors (Figure 12)
(e activation thermodynamic parameters for alumi-num dissolution could be obtained from the transition stateequation (8)
lnRcorr
T1113874 1113875 ln
R
Nh1113874 1113875 +
ΔSlowast
R1113888 1113889minus
ΔHlowast
RT1113888 1113889 (8)
where the entropy of activation ∆Slowast and the apparent en-thalpy of activation ∆Hlowast can be obtained from the intercept
3150
02
04
06
logR
corr
(gmiddoth
ndash1middotcm
ndash1)
08
1
12
32 325 331000T(Kndash1)
335 34 345
BlankMix ligandsZn2+
Co2+Ni2+Cu2+
Figure 12 Arrhenius of log corrosion rate (Rcorr) vs 1T for aluminum in 1M HCl without and with 004times10minus2MLminus1 of inhibitors (mixedligands and their metal complexes)
Table 9 (ermodynamic parameters for the adsorption of (004times10minus2)ML mixed ligands and their metal complexes on aluminum metalin aqueous solution of 1M HCl at different temperatures for 7 hrs
and the slope for the straight line of the relation betweenln(RcorrT) vs (1T) respectively N is Avogadrorsquos numberand h is Planckrsquos constant (e Gibbs free energy of acti-vation ∆Glowast can be detected by equation (9)
ΔGlowast ΔHlowast minusTΔSlowast (9)
Table 9 shows the thermodynamic parameters for theadsorption of mixed ligands and their metal complexes (epositive value of ∆Hlowast indicated the endothermic property ofdissolution process nature for aluminum in the acidicmedium [54]
However the blank ΔHlowast value is higher than the in-hibitor metal complexes which indicated that the inhibitionefficiency generally increases with increasing temperature(e association step is the rate-determining step rather thana dissociation process in presence of the metal complexesinhibitors due to the negative values of ΔSlowast It is known thatthe values of ΔGlowast above 40 kJmiddotmolminus1 are referred to chargetransfer from the inhibitor molecules into aluminum surfaceto form coordinated compound on the Al surface whichblocks it against corrosion process by different degrees Alsothe chemical adsorption process mechanism is confirmed bythe values of ΔGlowast above 40 kJmiddotmolminus1 [16 54ndash56]
4 Conclusions
Novel coordination materials of ternary divalent metalions (Cu(II) Ni(II) Co(II) and Zn(II)) chelated by thebidentate glutamic acid (Glu) and L-arginine (Arg) aminoacids are synthesized and characterized (e metal ionscomplexes are modelled using density DFT and TD-DFTtheory Computed molecular and spectroscopic (IR UV-Vis and EPR) properties validated the experimental re-sults (e used computational methods are capable ofproviding good structural descriptions for the TM com-plexes Consistent with the experimental properties theoptimized structures of the complexes [Cu(II) Glu-Arg]and [Co(II) Glu-Arg (H2O)2] reveal that symmetry en-vironment of Cu(II) exhibits slightly distorted squareplanar shape whereas Co(II)-complex has a distortedoctahedral (where Co(II) central ion is of C4v-localsymmetry) Spectral properties of [Ni(II) Glu-Arg(H2O)2] and [ZnmiddotGlumiddotArgmiddot(H2O)2] complexes indicatethat they have similar structure as Co(II) complex All thestudied ternary metal complexes are of different anti-fungal activities ranging from moderate to weak withoutpractically noticed inhibitory effects whereas antibacte-rial activities of all studied metal complexes show sig-nificant effects
Cytotoxicity studies against (HePG2) reveal the prom-ising potentiality of Cu(II) complex as inhibitor of cancercells(e results are correlated with the computed moleculardescriptors including dipole moment polarizability ther-modynamics and reactivity properties as well as the PESmaps
(e corrosion inhibition of aluminum metal specimensin 1M HCl is efficiently achieved by mixed ligands and theirmetal complexes studied
Data Availability
(e data used to support the findings of this study areavailable from the corresponding author upon request
Conflicts of Interest
(e authors declare that they have no conflicts of interest
Supplementary Materials
(e supplementary materials consist of six figures and twotables to further clarify the structures and trends of the newlyprepared metal ternary complexes (SupplementaryMaterials)
References
[1] Z Ozturk D A Kose A Asan et al ldquoPorous metal-organicCu(II) complex of L-Arginine 2synthesis characterizationhydrogen storage properties and molecular simulation cal-culationsrdquo Hittite Journal of Science and Engineering vol 1no 1 pp 1ndash5 2014
[2] S A Lahsasni R A Ammar M F Amin et al ldquoMixed-ligandcomplex formation of Cu(II) with 12- diphenylethylenedi-amine as primary ligand and amino acids as secondary li-gandsrdquo International Journal of Electrochemical Sciencevol 7 pp 7699ndash7711 2012
[3] H Sigel B P Operschall S S Massoud B Song andR Griesser ldquoEvidence for intramolecular aromatic-ringstacking in the physiological pH range of the mono-deprotonated xanthine residue in mixed-ligand complexescontaining xanthosinate 5prime-monophosphate (XMP)rdquo DaltonTransactions vol 46 no 46 pp 5521ndash5529 2006
[4] S Udhayakumar K G Shankar S Sowndarya S VenkateshC Muralidharan and C Rose ldquol-Arginine intercedes bio-crosslinking of a collagen-chitosan 3D-hybrid scaffold fortissue engineering and regeneration in silico in vitro and invivo studiesrdquo RSC Advances vol 7 no 40 pp 25070ndash250882017
[5] P K Datta M Chandra and A K Dey ldquoTernary complexesof copper(II) nickel(II) and zinc(II) with nitrilotriacetic acidas a primary ligand and some phenolic acids as secondaryligandsrdquo Transition Metal Chemistry vol 5 no 1ndash3 1980
[6] J S Woertink L Tian D Maiti et al ldquoSpectroscopic andcomputational studies of an end-on bound superoxo-Cu(II)complex geometric and electronic factors that determine theground staterdquo Inorganic Chemistry vol 49 no 20pp 9450ndash9459 2010
[7] S Dutta S Ray K Nagarajan et al ldquoGlutamic acid analoguesused as potent anticancer a reviewrdquo Der Pharma Chemicavol 3 no 2 pp 263ndash272 2011
[8] T Sismanoglu S Pura and A Bastug ldquoBinary and ternarymetal complexes of Congo red with amino acidsrdquo Dyes andPigments vol 70 no 2 pp 136ndash142 2006
[9] R N Patel H C Pandey K B Pandeya et al ldquoMixed ligandcomplex formation of nickel(II)copper(II) and zinc(II) withsome amino acids and imidazolesrdquo Indian Journal ofChemistry-Section A Inorganic Physical +eoretical andAnalytical Chemistry vol 38 no 8 pp 850ndash853 1999
[10] L Meng and Z Lin ldquoComplexations of alkalialkaline earthmetal cations with gaseous glutamic acidrdquo Computational and+eoretical Chemistry vol 1039 pp 1ndash10 2014
16 Journal of Chemistry
[11] L D Pinto P A L Puppin V M Behring O C AlvesN A Rey and J Felcman ldquoSolution and solid state study ofcopper(II) ternary complexes containing amino acids of in-terest for brain biochemistry-2 homocysteine with aspartateglutamate or methioninerdquo Inorganica Chimica Acta vol 386pp 60ndash67 2012
[12] A Wojciechowska A Ggor and W Zierkiewicz ldquoChiraloctahedral complexes of Co(III) as catalysts for asymmetricepoxidation of chalcones under phase transfer conditionsrdquoRSC Advances vol 5 no 46 pp 36295ndash36306 2015
[13] B M Weckhuysen A A Verberckmoes L Fu andR A Schoonheydt ldquoZeolite-encapsulated copper(II) aminoacid complexes synthesis spectroscopy and catalysisrdquo Journalof Physical Chemistry vol 100 no 22 pp 9456ndash9461 1996
[14] K Y El-Baradie N A El-Wakiel and H A El-GhamryldquoSynthesis characterization and corrosion inhibition in acidmedium ofl-histidine Schiff base complexesrdquo Applied Or-ganometallic Chemistry vol 29 no 3 pp 117ndash125 2015
[15] S S R Anthony and R Susai ldquoInhibition of corrosion ofcarbon steel in well water by arginine-Zn2+ systemrdquo Journal ofElectrochemical Science and Engineering vol 2 no 2pp 91ndash104 2012
[16] E H Isamil F F AlBlewi N Soliman and M M H Khalilldquo(ermal studies and mass loss inhibition for some newmixed amino acid metal complexes with their applicationsrdquoJournal of +ermal Analysis and Calorimetry vol 125 no 1pp 289ndash300 2016
[17] F Neese ldquo(e ORCA program system 4012rdquo Wiley In-terdisciplinary Reviews Computational Molecular Sciencevol 2 no 1 pp 73ndash78 2012
[18] S Grimme S Ehrlich and L Goerigk ldquoEffect of the dampingfunction in dispersion corrected density functional theoryrdquoJournal of Computational Chemistry vol 32 no 7pp 1456ndash1465 2011
[19] S Grimme J Antony S Ehrlich and H Krieg ldquoA consistentand accurate ab initio parametrization of density functionaldispersion correction (DFT-D) for the 94 elements H-Purdquo+e Journal of Chemical Physics vol 132 no 15 article154104 2010
[20] F Weigend ldquoHartree-Fock exchange fitting basis sets for H toRnrdquo Journal of Computational Chemistry vol 29 no 2pp 167ndash175 2008
[21] F Neese F Wennmohs and A Hansen ldquoEfficient ap-proximate and parallel Hartree-Fock and hybrid DFT cal-culations A lsquochain-of-spheresrsquo algorithm for the Hartree-Fock exchangerdquo Chemical Physics vol 356 no 1ndash3pp 98ndash109 2009
[22] R Izsak and F Neese ldquoAn overlap fitted chain of spheresexchange methodrdquo Journal of Chemical Physics vol 135no 14 article 144105 2011
[23] T Petrenko S Kossmann and F Neese ldquoEfficient time-dependent density functional theory approximations forhybrid density functionals analytical gradients and paralle-lizationrdquo Journal of Chemical Physics vol 134 no 5 article054116 2011
[24] A V Marenich C J Cramer and D G Truhlar ldquoUniversalsolvation model based on solute electron density and on acontinuum model of the solvent defined by the bulk dielectricconstant and atomic surface tensionsrdquo Journal of PhysicalChemistry B vol 113 no 18 pp 6378ndash96 2009
[25] S Donovan C Stiefbold and K Sprague ldquoChapter 3Chemical properties of amino acids and identification ofunknown amino acidsrdquo in Proceedings of the 17 thWorkshopConference of the Association for Biology
Laboratory Education (ABLE) vol 17 pp 35ndash70 Bain-bridge GA USA March 1996
[26] C C Wagner J Enrique and C Claudia ldquoVibrational andmagnetic properties of a CuMg glutamate complexrdquoArgentina Acta Farm Bonaerense vol 22 no 2 pp 137ndash1422003
[27] M Arif R Sur and M Arshad ldquoStudies on the thermaldecomposition of copper (II) flouride complexes with variousamino acids in nitrogen atmosphererdquo Turkish Journal ofChemistry vol 25 pp 73ndash79 2001
[28] A Ghosh M J Tucker and R M Hochstrasser ldquoIdentifi-cation of arginine residues in peptides by 2d-IR echo spec-troscopyrdquo Journal of Physical Chemistry A vol 115 no 34pp 9731ndash9738 2011
[29] K Nakamoto Infrared Spectra of Inorganic and CoordinationCompounds Part B Wiley-Interscience New York NY USA5th edition 1997
[30] E Santi M H Torre E Kremer S B Etcheverry andE J Baran ldquoVibrational spectra of the copper(II) and nick-el(II) complexes of piroxicamrdquo Vibrational Spectroscopyvol 5 no 3 pp 285ndash293 1993
[31] H N Aliyu and A S Mohammed ldquoSynthesis spectropho-tometric and biological activity of nickel (II) and copper (II)complexes with schiff base derived from acetylacetone andhistidinerdquo Global Advanced Research Journal of Microbiologyvol 1 no 5 pp 67ndash71 2012
[32] J S Murray and P Politzer ldquo(e electrostatic potential anoverviewrdquo Wiley Interdisciplinary Reviews ComputationalMolecular Science vol 1 no 2 pp 153ndash163 2011
[33] E R Souaya M M H Khalil and E H Ismail ldquoSynthesis andcharacterization of ternary complexes of certain hydroxylacids and their biological applicationsrdquo Research Journal ofPharmaceutical Biological and Chemical Sciences vol 5 no 4pp 18ndash30 2014
[34] N N Greenwood and A Earnshaw A Review of Chemistry ofthe Elements Pergamon Press Oxford UK 1984
[35] V Reddy N Patil and S D Angadi ldquoSynthesis character-ization and antimicrobial activity of Cu(II) Co(II) and Ni(II)complexes with ON and S Donor ligandsrdquo E-Journal ofChemistry vol 5 no 3 pp 577ndash583 2008
[36] F A Cotton G Wilkinson C A Murillo et al Advances inSchiff Base Chemistry Wiley New York NY USA 6th edi-tion 1999
[37] M M H Khalil E H Ismail S A Azim and E R SouayaldquoSynthesis characterization and thermal analysis of ternarycomplexes of nitrilotriacetic acid and alanine or phenylala-nine with some transition metalsrdquo Journal of +ermalAnalysis and Calorimetry vol 101 no 1 pp 129ndash135 2010
[38] F Mabbs and D Colisson Electron Paramagnetic Resonanceof D Transition Metal Compounds Vol 102 ElsevierAmsterdam Netherlands 1992
[39] M M H Khalil E R Souaya E H Ismail et al ldquoTernarytransition metal complexes of nitrilotriacetic acid and valineor leucine synthesis and biological applicationsrdquo ChineseJournal of Inorganic Chemistry vol 29 no 9 pp 1969ndash19782013
[40] I M Weiss C Muth R Drumm and H O K Kirchnerldquo(ermal decomposition of the amino acids glycine cysteineaspartic acid asparagine glutamic acid glutamine arginineand histidinerdquo BMC Biophysics vol 11 no 1 2018
[41] A M Petrosyan V V Ghazaryan G Giester and M FleckldquoSulfamates and methanesulfonates of L-arginine and L-his-tidinerdquo Journal of Molecular Structure vol 1163 pp 114ndash1272018
Journal of Chemistry 17
[42] T Kavitha S Haider T Kamal and M Ul-Islam ldquo(ermaldecomposition of metal complex precursor as route to thesynthesis of Co3O4 nanoparticles antibacterial activity andmechanismrdquo Journal of Alloys and Compounds vol 704pp 296ndash302 2017
[43] E M M Ibrahim L H Abdel-Rahman A M Abu-DiefA Elshafaie S K Hamdan and A M Ahmed ldquo(e synthesisof CuO andNiO nanoparticles by facile thermal decompositionof metal-Schiff base complexes and an examination of theirelectric thermoelectric and magnetic Propertiesrdquo MaterialsResearch Bulletin vol 107 pp 492ndash497 2018
[44] S Farhadi M Javanmard and G Nadri ldquoCharacterization ofcobalt oxide nanoparticles prepared by the thermal de-compositionrdquo Acta Chimica Slovenica vol 63 pp 335ndash3432016
[45] E M Zayed E H Ismail G G Mohamed M M H Khaliland A B Kamel ldquoSynthesis spectroscopic and structuralcharacterization and antimicrobial studies of metal com-plexes of a new hexadentate Schiff base ligand Spectropho-tometric determination of Fe(III) in water samples using arecovery testrdquo Monatshefte fur Chemie-Chemical Monthlyvol 145 no 5 pp 755ndash765 2014
[46] V Milacic D Chen L Ronconi K R Landis-PiwowarD Fregona and Q P Dou ldquoA novel anticancer gold(III)dithiocarbamate compound inhibits the activity of a purified20S proteasome and 26S proteasome in human breast cancercell cultures and xenograftsrdquo Cancer Research vol 66 no 21pp 10478ndash10486 2006
[47] T Mosmann ldquoRapid colorimetric assay for cellular growthand survival application to proliferation and cytotoxicityassaysrdquo Journal of Immunological Methods vol 65 no 1-2pp 55ndash63 1983
[48] R L Siegel K D Miller and A Jemal ldquoCancer statistics2018rdquo CA A Cancer Journal for Clinicians vol 68 no 1pp 7ndash30 2018
[49] S Chattopadhyay S P Chakraborty D Laha et al ldquoSurface-modified cobalt oxide nanoparticles new opportunities foranti-cancer drug developmentrdquo Cancer Nanotechnol vol 3no 1-6 pp 13ndash23 2012
[50] F Zielinski V Tognetti and L Joubert ldquoCondensed de-scriptors for reactivity a methodological studyrdquo ChemicalPhysics Letters vol 527 pp 67ndash72 2012
[51] H Wang Y He Q Yan et al ldquoCorrelation between thedielectric properties and biological activities of human ex vivohepatic tissuerdquo Physics in Medicine and Biology vol 60 no 6pp 2603ndash2617 2015
[52] F Tao F Fu F You et al ldquo(e correlation between dielectricproperties and microstructure of femoral bone in rats withdifferent bone qualitiesrdquo Annals of Biomedical Engineeringvol 42 no 6 pp 1238ndash1249 2014
[53] L Gun D Ning and Z Liang ldquoEffective permittivity ofbiological tissue comparison of theoretical model and ex-perimentrdquo Mathematical Problems in Engineering vol 2017Article ID 7249672 2017
[54] E I Ating S A Umoren I I Udousoro E E Ebenso andA P Udoh ldquoLeaves extract of Ananas sativumas greencorrosion inhibitor for aluminium in hydrochloric acid so-lutionsrdquo Green Chemistry Letters and Reviews vol 3 no 2pp 61ndash68 2010
[55] E Hamed ldquoStudies of the corrosion inhibition of copper inNa2SO4 solution using polarization and electrochemicalimpedance spectroscopyrdquo Materials Chemistry and Physicsvol 121 no 1-2 pp 70ndash76 2010
[56] H Zarrok H Oudda A Zarrouk et al ldquoWeight loss mea-surement and theoretical study of new pyridazine compoundas corrosion inhibitor for C38 steel in hydrochloric acidsolutionrdquo Der Pharma Chemica vol 3 no 6 pp 576ndash5902011
18 Journal of Chemistry
TribologyAdvances in
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
International Journal ofInternational Journal ofPhotoenergy
Hindawiwwwhindawicom Volume 2018
Journal of
Chemistry
Hindawiwwwhindawicom Volume 2018
Advances inPhysical Chemistry
Hindawiwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2018
Bioinorganic Chemistry and ApplicationsHindawiwwwhindawicom Volume 2018
SpectroscopyAnalytical ChemistryInternational Journal of
Hindawiwwwhindawicom Volume 2018
MaterialsJournal of
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
BioMed Research International Electrochemistry
International Journal of
Hindawiwwwhindawicom Volume 2018
Na
nom
ate
ria
ls
Hindawiwwwhindawicom Volume 2018
Journal ofNanomaterials
Submit your manuscripts atwwwhindawicom
where Rblank corrosion rates in the absence of inhibitor andRinh corrosion rates in the presence of inhibitor [16]
Table 8 shows the calculated corrosion rates and inhibitionefficiencies of aluminum specimens in aqueous solution of 1MHCl as the corrosive medium in absence and presence ofmixed ligands and their ternary metal complexes at differenttemperatures (293 ndash313) K for 7 hours of each concentrationFigure 6S shows that as the concentration of ligands and theircomplexes increases Rcorr decreases and IE increases formixed ligands and their metal complexes acted as more ef-ficient inhibitors than their mixed ligands alone
344 Adsorption Isotherms and the +ermodynamic Acti-vation Parameters (e metal surface coverage degree(θIE100) was subjected to different adsorption iso-therms (e well fit for weight loss data is obtained forLangmuir adsorption isotherm Figure 11
Table 8 Corrosion parameters for aluminum in aqueous solution of 1M HCl in the absence and presence of different concentrations ofmixed ligands and their metal complexes at different temperatures for 7 hrs
Inhibitors C (times10minus2M)Corrosion rate times10minus4
Figure 11 Langmuir adsorption isotherms of the mixed ligands(L) and their metal complexes
14 Journal of Chemistry
(e temperature effect (293ndash313 K) on aluminum weightloss inhibition may be attributed to two main mechanismsphysical and chemical adsorption [37] (e suggested mech-anisms are obtained as the temperature increases the efficiencydecreases for mixed ligands but increases for their metalcomplexes depending on the nature of bond formation be-tween the mixed ligands and aluminum surface which isdifferent from the nature of bond formation between metalcomplexes and the aluminum surface [16] Arrhenius equation(7) gives the relation between the corrosion rate andtemperature
lnRcorr lnAminusElowast
RT (7)
where A is the Arrhenius factor Elowast is the apparent activationenergy of the corrosion process R is the rate gas constant andT is the absolute temperature (e straight line slope oflogRcorr vs 1T for aluminum 1M HCl at 4times10minus4molL after7 h is minusElowast2303R for the inhibitors (Figure 12)
(e activation thermodynamic parameters for alumi-num dissolution could be obtained from the transition stateequation (8)
lnRcorr
T1113874 1113875 ln
R
Nh1113874 1113875 +
ΔSlowast
R1113888 1113889minus
ΔHlowast
RT1113888 1113889 (8)
where the entropy of activation ∆Slowast and the apparent en-thalpy of activation ∆Hlowast can be obtained from the intercept
3150
02
04
06
logR
corr
(gmiddoth
ndash1middotcm
ndash1)
08
1
12
32 325 331000T(Kndash1)
335 34 345
BlankMix ligandsZn2+
Co2+Ni2+Cu2+
Figure 12 Arrhenius of log corrosion rate (Rcorr) vs 1T for aluminum in 1M HCl without and with 004times10minus2MLminus1 of inhibitors (mixedligands and their metal complexes)
Table 9 (ermodynamic parameters for the adsorption of (004times10minus2)ML mixed ligands and their metal complexes on aluminum metalin aqueous solution of 1M HCl at different temperatures for 7 hrs
and the slope for the straight line of the relation betweenln(RcorrT) vs (1T) respectively N is Avogadrorsquos numberand h is Planckrsquos constant (e Gibbs free energy of acti-vation ∆Glowast can be detected by equation (9)
ΔGlowast ΔHlowast minusTΔSlowast (9)
Table 9 shows the thermodynamic parameters for theadsorption of mixed ligands and their metal complexes (epositive value of ∆Hlowast indicated the endothermic property ofdissolution process nature for aluminum in the acidicmedium [54]
However the blank ΔHlowast value is higher than the in-hibitor metal complexes which indicated that the inhibitionefficiency generally increases with increasing temperature(e association step is the rate-determining step rather thana dissociation process in presence of the metal complexesinhibitors due to the negative values of ΔSlowast It is known thatthe values of ΔGlowast above 40 kJmiddotmolminus1 are referred to chargetransfer from the inhibitor molecules into aluminum surfaceto form coordinated compound on the Al surface whichblocks it against corrosion process by different degrees Alsothe chemical adsorption process mechanism is confirmed bythe values of ΔGlowast above 40 kJmiddotmolminus1 [16 54ndash56]
4 Conclusions
Novel coordination materials of ternary divalent metalions (Cu(II) Ni(II) Co(II) and Zn(II)) chelated by thebidentate glutamic acid (Glu) and L-arginine (Arg) aminoacids are synthesized and characterized (e metal ionscomplexes are modelled using density DFT and TD-DFTtheory Computed molecular and spectroscopic (IR UV-Vis and EPR) properties validated the experimental re-sults (e used computational methods are capable ofproviding good structural descriptions for the TM com-plexes Consistent with the experimental properties theoptimized structures of the complexes [Cu(II) Glu-Arg]and [Co(II) Glu-Arg (H2O)2] reveal that symmetry en-vironment of Cu(II) exhibits slightly distorted squareplanar shape whereas Co(II)-complex has a distortedoctahedral (where Co(II) central ion is of C4v-localsymmetry) Spectral properties of [Ni(II) Glu-Arg(H2O)2] and [ZnmiddotGlumiddotArgmiddot(H2O)2] complexes indicatethat they have similar structure as Co(II) complex All thestudied ternary metal complexes are of different anti-fungal activities ranging from moderate to weak withoutpractically noticed inhibitory effects whereas antibacte-rial activities of all studied metal complexes show sig-nificant effects
Cytotoxicity studies against (HePG2) reveal the prom-ising potentiality of Cu(II) complex as inhibitor of cancercells(e results are correlated with the computed moleculardescriptors including dipole moment polarizability ther-modynamics and reactivity properties as well as the PESmaps
(e corrosion inhibition of aluminum metal specimensin 1M HCl is efficiently achieved by mixed ligands and theirmetal complexes studied
Data Availability
(e data used to support the findings of this study areavailable from the corresponding author upon request
Conflicts of Interest
(e authors declare that they have no conflicts of interest
Supplementary Materials
(e supplementary materials consist of six figures and twotables to further clarify the structures and trends of the newlyprepared metal ternary complexes (SupplementaryMaterials)
References
[1] Z Ozturk D A Kose A Asan et al ldquoPorous metal-organicCu(II) complex of L-Arginine 2synthesis characterizationhydrogen storage properties and molecular simulation cal-culationsrdquo Hittite Journal of Science and Engineering vol 1no 1 pp 1ndash5 2014
[2] S A Lahsasni R A Ammar M F Amin et al ldquoMixed-ligandcomplex formation of Cu(II) with 12- diphenylethylenedi-amine as primary ligand and amino acids as secondary li-gandsrdquo International Journal of Electrochemical Sciencevol 7 pp 7699ndash7711 2012
[3] H Sigel B P Operschall S S Massoud B Song andR Griesser ldquoEvidence for intramolecular aromatic-ringstacking in the physiological pH range of the mono-deprotonated xanthine residue in mixed-ligand complexescontaining xanthosinate 5prime-monophosphate (XMP)rdquo DaltonTransactions vol 46 no 46 pp 5521ndash5529 2006
[4] S Udhayakumar K G Shankar S Sowndarya S VenkateshC Muralidharan and C Rose ldquol-Arginine intercedes bio-crosslinking of a collagen-chitosan 3D-hybrid scaffold fortissue engineering and regeneration in silico in vitro and invivo studiesrdquo RSC Advances vol 7 no 40 pp 25070ndash250882017
[5] P K Datta M Chandra and A K Dey ldquoTernary complexesof copper(II) nickel(II) and zinc(II) with nitrilotriacetic acidas a primary ligand and some phenolic acids as secondaryligandsrdquo Transition Metal Chemistry vol 5 no 1ndash3 1980
[6] J S Woertink L Tian D Maiti et al ldquoSpectroscopic andcomputational studies of an end-on bound superoxo-Cu(II)complex geometric and electronic factors that determine theground staterdquo Inorganic Chemistry vol 49 no 20pp 9450ndash9459 2010
[7] S Dutta S Ray K Nagarajan et al ldquoGlutamic acid analoguesused as potent anticancer a reviewrdquo Der Pharma Chemicavol 3 no 2 pp 263ndash272 2011
[8] T Sismanoglu S Pura and A Bastug ldquoBinary and ternarymetal complexes of Congo red with amino acidsrdquo Dyes andPigments vol 70 no 2 pp 136ndash142 2006
[9] R N Patel H C Pandey K B Pandeya et al ldquoMixed ligandcomplex formation of nickel(II)copper(II) and zinc(II) withsome amino acids and imidazolesrdquo Indian Journal ofChemistry-Section A Inorganic Physical +eoretical andAnalytical Chemistry vol 38 no 8 pp 850ndash853 1999
[10] L Meng and Z Lin ldquoComplexations of alkalialkaline earthmetal cations with gaseous glutamic acidrdquo Computational and+eoretical Chemistry vol 1039 pp 1ndash10 2014
16 Journal of Chemistry
[11] L D Pinto P A L Puppin V M Behring O C AlvesN A Rey and J Felcman ldquoSolution and solid state study ofcopper(II) ternary complexes containing amino acids of in-terest for brain biochemistry-2 homocysteine with aspartateglutamate or methioninerdquo Inorganica Chimica Acta vol 386pp 60ndash67 2012
[12] A Wojciechowska A Ggor and W Zierkiewicz ldquoChiraloctahedral complexes of Co(III) as catalysts for asymmetricepoxidation of chalcones under phase transfer conditionsrdquoRSC Advances vol 5 no 46 pp 36295ndash36306 2015
[13] B M Weckhuysen A A Verberckmoes L Fu andR A Schoonheydt ldquoZeolite-encapsulated copper(II) aminoacid complexes synthesis spectroscopy and catalysisrdquo Journalof Physical Chemistry vol 100 no 22 pp 9456ndash9461 1996
[14] K Y El-Baradie N A El-Wakiel and H A El-GhamryldquoSynthesis characterization and corrosion inhibition in acidmedium ofl-histidine Schiff base complexesrdquo Applied Or-ganometallic Chemistry vol 29 no 3 pp 117ndash125 2015
[15] S S R Anthony and R Susai ldquoInhibition of corrosion ofcarbon steel in well water by arginine-Zn2+ systemrdquo Journal ofElectrochemical Science and Engineering vol 2 no 2pp 91ndash104 2012
[16] E H Isamil F F AlBlewi N Soliman and M M H Khalilldquo(ermal studies and mass loss inhibition for some newmixed amino acid metal complexes with their applicationsrdquoJournal of +ermal Analysis and Calorimetry vol 125 no 1pp 289ndash300 2016
[17] F Neese ldquo(e ORCA program system 4012rdquo Wiley In-terdisciplinary Reviews Computational Molecular Sciencevol 2 no 1 pp 73ndash78 2012
[18] S Grimme S Ehrlich and L Goerigk ldquoEffect of the dampingfunction in dispersion corrected density functional theoryrdquoJournal of Computational Chemistry vol 32 no 7pp 1456ndash1465 2011
[19] S Grimme J Antony S Ehrlich and H Krieg ldquoA consistentand accurate ab initio parametrization of density functionaldispersion correction (DFT-D) for the 94 elements H-Purdquo+e Journal of Chemical Physics vol 132 no 15 article154104 2010
[20] F Weigend ldquoHartree-Fock exchange fitting basis sets for H toRnrdquo Journal of Computational Chemistry vol 29 no 2pp 167ndash175 2008
[21] F Neese F Wennmohs and A Hansen ldquoEfficient ap-proximate and parallel Hartree-Fock and hybrid DFT cal-culations A lsquochain-of-spheresrsquo algorithm for the Hartree-Fock exchangerdquo Chemical Physics vol 356 no 1ndash3pp 98ndash109 2009
[22] R Izsak and F Neese ldquoAn overlap fitted chain of spheresexchange methodrdquo Journal of Chemical Physics vol 135no 14 article 144105 2011
[23] T Petrenko S Kossmann and F Neese ldquoEfficient time-dependent density functional theory approximations forhybrid density functionals analytical gradients and paralle-lizationrdquo Journal of Chemical Physics vol 134 no 5 article054116 2011
[24] A V Marenich C J Cramer and D G Truhlar ldquoUniversalsolvation model based on solute electron density and on acontinuum model of the solvent defined by the bulk dielectricconstant and atomic surface tensionsrdquo Journal of PhysicalChemistry B vol 113 no 18 pp 6378ndash96 2009
[25] S Donovan C Stiefbold and K Sprague ldquoChapter 3Chemical properties of amino acids and identification ofunknown amino acidsrdquo in Proceedings of the 17 thWorkshopConference of the Association for Biology
Laboratory Education (ABLE) vol 17 pp 35ndash70 Bain-bridge GA USA March 1996
[26] C C Wagner J Enrique and C Claudia ldquoVibrational andmagnetic properties of a CuMg glutamate complexrdquoArgentina Acta Farm Bonaerense vol 22 no 2 pp 137ndash1422003
[27] M Arif R Sur and M Arshad ldquoStudies on the thermaldecomposition of copper (II) flouride complexes with variousamino acids in nitrogen atmosphererdquo Turkish Journal ofChemistry vol 25 pp 73ndash79 2001
[28] A Ghosh M J Tucker and R M Hochstrasser ldquoIdentifi-cation of arginine residues in peptides by 2d-IR echo spec-troscopyrdquo Journal of Physical Chemistry A vol 115 no 34pp 9731ndash9738 2011
[29] K Nakamoto Infrared Spectra of Inorganic and CoordinationCompounds Part B Wiley-Interscience New York NY USA5th edition 1997
[30] E Santi M H Torre E Kremer S B Etcheverry andE J Baran ldquoVibrational spectra of the copper(II) and nick-el(II) complexes of piroxicamrdquo Vibrational Spectroscopyvol 5 no 3 pp 285ndash293 1993
[31] H N Aliyu and A S Mohammed ldquoSynthesis spectropho-tometric and biological activity of nickel (II) and copper (II)complexes with schiff base derived from acetylacetone andhistidinerdquo Global Advanced Research Journal of Microbiologyvol 1 no 5 pp 67ndash71 2012
[32] J S Murray and P Politzer ldquo(e electrostatic potential anoverviewrdquo Wiley Interdisciplinary Reviews ComputationalMolecular Science vol 1 no 2 pp 153ndash163 2011
[33] E R Souaya M M H Khalil and E H Ismail ldquoSynthesis andcharacterization of ternary complexes of certain hydroxylacids and their biological applicationsrdquo Research Journal ofPharmaceutical Biological and Chemical Sciences vol 5 no 4pp 18ndash30 2014
[34] N N Greenwood and A Earnshaw A Review of Chemistry ofthe Elements Pergamon Press Oxford UK 1984
[35] V Reddy N Patil and S D Angadi ldquoSynthesis character-ization and antimicrobial activity of Cu(II) Co(II) and Ni(II)complexes with ON and S Donor ligandsrdquo E-Journal ofChemistry vol 5 no 3 pp 577ndash583 2008
[36] F A Cotton G Wilkinson C A Murillo et al Advances inSchiff Base Chemistry Wiley New York NY USA 6th edi-tion 1999
[37] M M H Khalil E H Ismail S A Azim and E R SouayaldquoSynthesis characterization and thermal analysis of ternarycomplexes of nitrilotriacetic acid and alanine or phenylala-nine with some transition metalsrdquo Journal of +ermalAnalysis and Calorimetry vol 101 no 1 pp 129ndash135 2010
[38] F Mabbs and D Colisson Electron Paramagnetic Resonanceof D Transition Metal Compounds Vol 102 ElsevierAmsterdam Netherlands 1992
[39] M M H Khalil E R Souaya E H Ismail et al ldquoTernarytransition metal complexes of nitrilotriacetic acid and valineor leucine synthesis and biological applicationsrdquo ChineseJournal of Inorganic Chemistry vol 29 no 9 pp 1969ndash19782013
[40] I M Weiss C Muth R Drumm and H O K Kirchnerldquo(ermal decomposition of the amino acids glycine cysteineaspartic acid asparagine glutamic acid glutamine arginineand histidinerdquo BMC Biophysics vol 11 no 1 2018
[41] A M Petrosyan V V Ghazaryan G Giester and M FleckldquoSulfamates and methanesulfonates of L-arginine and L-his-tidinerdquo Journal of Molecular Structure vol 1163 pp 114ndash1272018
Journal of Chemistry 17
[42] T Kavitha S Haider T Kamal and M Ul-Islam ldquo(ermaldecomposition of metal complex precursor as route to thesynthesis of Co3O4 nanoparticles antibacterial activity andmechanismrdquo Journal of Alloys and Compounds vol 704pp 296ndash302 2017
[43] E M M Ibrahim L H Abdel-Rahman A M Abu-DiefA Elshafaie S K Hamdan and A M Ahmed ldquo(e synthesisof CuO andNiO nanoparticles by facile thermal decompositionof metal-Schiff base complexes and an examination of theirelectric thermoelectric and magnetic Propertiesrdquo MaterialsResearch Bulletin vol 107 pp 492ndash497 2018
[44] S Farhadi M Javanmard and G Nadri ldquoCharacterization ofcobalt oxide nanoparticles prepared by the thermal de-compositionrdquo Acta Chimica Slovenica vol 63 pp 335ndash3432016
[45] E M Zayed E H Ismail G G Mohamed M M H Khaliland A B Kamel ldquoSynthesis spectroscopic and structuralcharacterization and antimicrobial studies of metal com-plexes of a new hexadentate Schiff base ligand Spectropho-tometric determination of Fe(III) in water samples using arecovery testrdquo Monatshefte fur Chemie-Chemical Monthlyvol 145 no 5 pp 755ndash765 2014
[46] V Milacic D Chen L Ronconi K R Landis-PiwowarD Fregona and Q P Dou ldquoA novel anticancer gold(III)dithiocarbamate compound inhibits the activity of a purified20S proteasome and 26S proteasome in human breast cancercell cultures and xenograftsrdquo Cancer Research vol 66 no 21pp 10478ndash10486 2006
[47] T Mosmann ldquoRapid colorimetric assay for cellular growthand survival application to proliferation and cytotoxicityassaysrdquo Journal of Immunological Methods vol 65 no 1-2pp 55ndash63 1983
[48] R L Siegel K D Miller and A Jemal ldquoCancer statistics2018rdquo CA A Cancer Journal for Clinicians vol 68 no 1pp 7ndash30 2018
[49] S Chattopadhyay S P Chakraborty D Laha et al ldquoSurface-modified cobalt oxide nanoparticles new opportunities foranti-cancer drug developmentrdquo Cancer Nanotechnol vol 3no 1-6 pp 13ndash23 2012
[50] F Zielinski V Tognetti and L Joubert ldquoCondensed de-scriptors for reactivity a methodological studyrdquo ChemicalPhysics Letters vol 527 pp 67ndash72 2012
[51] H Wang Y He Q Yan et al ldquoCorrelation between thedielectric properties and biological activities of human ex vivohepatic tissuerdquo Physics in Medicine and Biology vol 60 no 6pp 2603ndash2617 2015
[52] F Tao F Fu F You et al ldquo(e correlation between dielectricproperties and microstructure of femoral bone in rats withdifferent bone qualitiesrdquo Annals of Biomedical Engineeringvol 42 no 6 pp 1238ndash1249 2014
[53] L Gun D Ning and Z Liang ldquoEffective permittivity ofbiological tissue comparison of theoretical model and ex-perimentrdquo Mathematical Problems in Engineering vol 2017Article ID 7249672 2017
[54] E I Ating S A Umoren I I Udousoro E E Ebenso andA P Udoh ldquoLeaves extract of Ananas sativumas greencorrosion inhibitor for aluminium in hydrochloric acid so-lutionsrdquo Green Chemistry Letters and Reviews vol 3 no 2pp 61ndash68 2010
[55] E Hamed ldquoStudies of the corrosion inhibition of copper inNa2SO4 solution using polarization and electrochemicalimpedance spectroscopyrdquo Materials Chemistry and Physicsvol 121 no 1-2 pp 70ndash76 2010
[56] H Zarrok H Oudda A Zarrouk et al ldquoWeight loss mea-surement and theoretical study of new pyridazine compoundas corrosion inhibitor for C38 steel in hydrochloric acidsolutionrdquo Der Pharma Chemica vol 3 no 6 pp 576ndash5902011
18 Journal of Chemistry
TribologyAdvances in
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
International Journal ofInternational Journal ofPhotoenergy
Hindawiwwwhindawicom Volume 2018
Journal of
Chemistry
Hindawiwwwhindawicom Volume 2018
Advances inPhysical Chemistry
Hindawiwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2018
Bioinorganic Chemistry and ApplicationsHindawiwwwhindawicom Volume 2018
SpectroscopyAnalytical ChemistryInternational Journal of
Hindawiwwwhindawicom Volume 2018
MaterialsJournal of
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
BioMed Research International Electrochemistry
International Journal of
Hindawiwwwhindawicom Volume 2018
Na
nom
ate
ria
ls
Hindawiwwwhindawicom Volume 2018
Journal ofNanomaterials
Submit your manuscripts atwwwhindawicom
(e temperature effect (293ndash313 K) on aluminum weightloss inhibition may be attributed to two main mechanismsphysical and chemical adsorption [37] (e suggested mech-anisms are obtained as the temperature increases the efficiencydecreases for mixed ligands but increases for their metalcomplexes depending on the nature of bond formation be-tween the mixed ligands and aluminum surface which isdifferent from the nature of bond formation between metalcomplexes and the aluminum surface [16] Arrhenius equation(7) gives the relation between the corrosion rate andtemperature
lnRcorr lnAminusElowast
RT (7)
where A is the Arrhenius factor Elowast is the apparent activationenergy of the corrosion process R is the rate gas constant andT is the absolute temperature (e straight line slope oflogRcorr vs 1T for aluminum 1M HCl at 4times10minus4molL after7 h is minusElowast2303R for the inhibitors (Figure 12)
(e activation thermodynamic parameters for alumi-num dissolution could be obtained from the transition stateequation (8)
lnRcorr
T1113874 1113875 ln
R
Nh1113874 1113875 +
ΔSlowast
R1113888 1113889minus
ΔHlowast
RT1113888 1113889 (8)
where the entropy of activation ∆Slowast and the apparent en-thalpy of activation ∆Hlowast can be obtained from the intercept
3150
02
04
06
logR
corr
(gmiddoth
ndash1middotcm
ndash1)
08
1
12
32 325 331000T(Kndash1)
335 34 345
BlankMix ligandsZn2+
Co2+Ni2+Cu2+
Figure 12 Arrhenius of log corrosion rate (Rcorr) vs 1T for aluminum in 1M HCl without and with 004times10minus2MLminus1 of inhibitors (mixedligands and their metal complexes)
Table 9 (ermodynamic parameters for the adsorption of (004times10minus2)ML mixed ligands and their metal complexes on aluminum metalin aqueous solution of 1M HCl at different temperatures for 7 hrs
and the slope for the straight line of the relation betweenln(RcorrT) vs (1T) respectively N is Avogadrorsquos numberand h is Planckrsquos constant (e Gibbs free energy of acti-vation ∆Glowast can be detected by equation (9)
ΔGlowast ΔHlowast minusTΔSlowast (9)
Table 9 shows the thermodynamic parameters for theadsorption of mixed ligands and their metal complexes (epositive value of ∆Hlowast indicated the endothermic property ofdissolution process nature for aluminum in the acidicmedium [54]
However the blank ΔHlowast value is higher than the in-hibitor metal complexes which indicated that the inhibitionefficiency generally increases with increasing temperature(e association step is the rate-determining step rather thana dissociation process in presence of the metal complexesinhibitors due to the negative values of ΔSlowast It is known thatthe values of ΔGlowast above 40 kJmiddotmolminus1 are referred to chargetransfer from the inhibitor molecules into aluminum surfaceto form coordinated compound on the Al surface whichblocks it against corrosion process by different degrees Alsothe chemical adsorption process mechanism is confirmed bythe values of ΔGlowast above 40 kJmiddotmolminus1 [16 54ndash56]
4 Conclusions
Novel coordination materials of ternary divalent metalions (Cu(II) Ni(II) Co(II) and Zn(II)) chelated by thebidentate glutamic acid (Glu) and L-arginine (Arg) aminoacids are synthesized and characterized (e metal ionscomplexes are modelled using density DFT and TD-DFTtheory Computed molecular and spectroscopic (IR UV-Vis and EPR) properties validated the experimental re-sults (e used computational methods are capable ofproviding good structural descriptions for the TM com-plexes Consistent with the experimental properties theoptimized structures of the complexes [Cu(II) Glu-Arg]and [Co(II) Glu-Arg (H2O)2] reveal that symmetry en-vironment of Cu(II) exhibits slightly distorted squareplanar shape whereas Co(II)-complex has a distortedoctahedral (where Co(II) central ion is of C4v-localsymmetry) Spectral properties of [Ni(II) Glu-Arg(H2O)2] and [ZnmiddotGlumiddotArgmiddot(H2O)2] complexes indicatethat they have similar structure as Co(II) complex All thestudied ternary metal complexes are of different anti-fungal activities ranging from moderate to weak withoutpractically noticed inhibitory effects whereas antibacte-rial activities of all studied metal complexes show sig-nificant effects
Cytotoxicity studies against (HePG2) reveal the prom-ising potentiality of Cu(II) complex as inhibitor of cancercells(e results are correlated with the computed moleculardescriptors including dipole moment polarizability ther-modynamics and reactivity properties as well as the PESmaps
(e corrosion inhibition of aluminum metal specimensin 1M HCl is efficiently achieved by mixed ligands and theirmetal complexes studied
Data Availability
(e data used to support the findings of this study areavailable from the corresponding author upon request
Conflicts of Interest
(e authors declare that they have no conflicts of interest
Supplementary Materials
(e supplementary materials consist of six figures and twotables to further clarify the structures and trends of the newlyprepared metal ternary complexes (SupplementaryMaterials)
References
[1] Z Ozturk D A Kose A Asan et al ldquoPorous metal-organicCu(II) complex of L-Arginine 2synthesis characterizationhydrogen storage properties and molecular simulation cal-culationsrdquo Hittite Journal of Science and Engineering vol 1no 1 pp 1ndash5 2014
[2] S A Lahsasni R A Ammar M F Amin et al ldquoMixed-ligandcomplex formation of Cu(II) with 12- diphenylethylenedi-amine as primary ligand and amino acids as secondary li-gandsrdquo International Journal of Electrochemical Sciencevol 7 pp 7699ndash7711 2012
[3] H Sigel B P Operschall S S Massoud B Song andR Griesser ldquoEvidence for intramolecular aromatic-ringstacking in the physiological pH range of the mono-deprotonated xanthine residue in mixed-ligand complexescontaining xanthosinate 5prime-monophosphate (XMP)rdquo DaltonTransactions vol 46 no 46 pp 5521ndash5529 2006
[4] S Udhayakumar K G Shankar S Sowndarya S VenkateshC Muralidharan and C Rose ldquol-Arginine intercedes bio-crosslinking of a collagen-chitosan 3D-hybrid scaffold fortissue engineering and regeneration in silico in vitro and invivo studiesrdquo RSC Advances vol 7 no 40 pp 25070ndash250882017
[5] P K Datta M Chandra and A K Dey ldquoTernary complexesof copper(II) nickel(II) and zinc(II) with nitrilotriacetic acidas a primary ligand and some phenolic acids as secondaryligandsrdquo Transition Metal Chemistry vol 5 no 1ndash3 1980
[6] J S Woertink L Tian D Maiti et al ldquoSpectroscopic andcomputational studies of an end-on bound superoxo-Cu(II)complex geometric and electronic factors that determine theground staterdquo Inorganic Chemistry vol 49 no 20pp 9450ndash9459 2010
[7] S Dutta S Ray K Nagarajan et al ldquoGlutamic acid analoguesused as potent anticancer a reviewrdquo Der Pharma Chemicavol 3 no 2 pp 263ndash272 2011
[8] T Sismanoglu S Pura and A Bastug ldquoBinary and ternarymetal complexes of Congo red with amino acidsrdquo Dyes andPigments vol 70 no 2 pp 136ndash142 2006
[9] R N Patel H C Pandey K B Pandeya et al ldquoMixed ligandcomplex formation of nickel(II)copper(II) and zinc(II) withsome amino acids and imidazolesrdquo Indian Journal ofChemistry-Section A Inorganic Physical +eoretical andAnalytical Chemistry vol 38 no 8 pp 850ndash853 1999
[10] L Meng and Z Lin ldquoComplexations of alkalialkaline earthmetal cations with gaseous glutamic acidrdquo Computational and+eoretical Chemistry vol 1039 pp 1ndash10 2014
16 Journal of Chemistry
[11] L D Pinto P A L Puppin V M Behring O C AlvesN A Rey and J Felcman ldquoSolution and solid state study ofcopper(II) ternary complexes containing amino acids of in-terest for brain biochemistry-2 homocysteine with aspartateglutamate or methioninerdquo Inorganica Chimica Acta vol 386pp 60ndash67 2012
[12] A Wojciechowska A Ggor and W Zierkiewicz ldquoChiraloctahedral complexes of Co(III) as catalysts for asymmetricepoxidation of chalcones under phase transfer conditionsrdquoRSC Advances vol 5 no 46 pp 36295ndash36306 2015
[13] B M Weckhuysen A A Verberckmoes L Fu andR A Schoonheydt ldquoZeolite-encapsulated copper(II) aminoacid complexes synthesis spectroscopy and catalysisrdquo Journalof Physical Chemistry vol 100 no 22 pp 9456ndash9461 1996
[14] K Y El-Baradie N A El-Wakiel and H A El-GhamryldquoSynthesis characterization and corrosion inhibition in acidmedium ofl-histidine Schiff base complexesrdquo Applied Or-ganometallic Chemistry vol 29 no 3 pp 117ndash125 2015
[15] S S R Anthony and R Susai ldquoInhibition of corrosion ofcarbon steel in well water by arginine-Zn2+ systemrdquo Journal ofElectrochemical Science and Engineering vol 2 no 2pp 91ndash104 2012
[16] E H Isamil F F AlBlewi N Soliman and M M H Khalilldquo(ermal studies and mass loss inhibition for some newmixed amino acid metal complexes with their applicationsrdquoJournal of +ermal Analysis and Calorimetry vol 125 no 1pp 289ndash300 2016
[17] F Neese ldquo(e ORCA program system 4012rdquo Wiley In-terdisciplinary Reviews Computational Molecular Sciencevol 2 no 1 pp 73ndash78 2012
[18] S Grimme S Ehrlich and L Goerigk ldquoEffect of the dampingfunction in dispersion corrected density functional theoryrdquoJournal of Computational Chemistry vol 32 no 7pp 1456ndash1465 2011
[19] S Grimme J Antony S Ehrlich and H Krieg ldquoA consistentand accurate ab initio parametrization of density functionaldispersion correction (DFT-D) for the 94 elements H-Purdquo+e Journal of Chemical Physics vol 132 no 15 article154104 2010
[20] F Weigend ldquoHartree-Fock exchange fitting basis sets for H toRnrdquo Journal of Computational Chemistry vol 29 no 2pp 167ndash175 2008
[21] F Neese F Wennmohs and A Hansen ldquoEfficient ap-proximate and parallel Hartree-Fock and hybrid DFT cal-culations A lsquochain-of-spheresrsquo algorithm for the Hartree-Fock exchangerdquo Chemical Physics vol 356 no 1ndash3pp 98ndash109 2009
[22] R Izsak and F Neese ldquoAn overlap fitted chain of spheresexchange methodrdquo Journal of Chemical Physics vol 135no 14 article 144105 2011
[23] T Petrenko S Kossmann and F Neese ldquoEfficient time-dependent density functional theory approximations forhybrid density functionals analytical gradients and paralle-lizationrdquo Journal of Chemical Physics vol 134 no 5 article054116 2011
[24] A V Marenich C J Cramer and D G Truhlar ldquoUniversalsolvation model based on solute electron density and on acontinuum model of the solvent defined by the bulk dielectricconstant and atomic surface tensionsrdquo Journal of PhysicalChemistry B vol 113 no 18 pp 6378ndash96 2009
[25] S Donovan C Stiefbold and K Sprague ldquoChapter 3Chemical properties of amino acids and identification ofunknown amino acidsrdquo in Proceedings of the 17 thWorkshopConference of the Association for Biology
Laboratory Education (ABLE) vol 17 pp 35ndash70 Bain-bridge GA USA March 1996
[26] C C Wagner J Enrique and C Claudia ldquoVibrational andmagnetic properties of a CuMg glutamate complexrdquoArgentina Acta Farm Bonaerense vol 22 no 2 pp 137ndash1422003
[27] M Arif R Sur and M Arshad ldquoStudies on the thermaldecomposition of copper (II) flouride complexes with variousamino acids in nitrogen atmosphererdquo Turkish Journal ofChemistry vol 25 pp 73ndash79 2001
[28] A Ghosh M J Tucker and R M Hochstrasser ldquoIdentifi-cation of arginine residues in peptides by 2d-IR echo spec-troscopyrdquo Journal of Physical Chemistry A vol 115 no 34pp 9731ndash9738 2011
[29] K Nakamoto Infrared Spectra of Inorganic and CoordinationCompounds Part B Wiley-Interscience New York NY USA5th edition 1997
[30] E Santi M H Torre E Kremer S B Etcheverry andE J Baran ldquoVibrational spectra of the copper(II) and nick-el(II) complexes of piroxicamrdquo Vibrational Spectroscopyvol 5 no 3 pp 285ndash293 1993
[31] H N Aliyu and A S Mohammed ldquoSynthesis spectropho-tometric and biological activity of nickel (II) and copper (II)complexes with schiff base derived from acetylacetone andhistidinerdquo Global Advanced Research Journal of Microbiologyvol 1 no 5 pp 67ndash71 2012
[32] J S Murray and P Politzer ldquo(e electrostatic potential anoverviewrdquo Wiley Interdisciplinary Reviews ComputationalMolecular Science vol 1 no 2 pp 153ndash163 2011
[33] E R Souaya M M H Khalil and E H Ismail ldquoSynthesis andcharacterization of ternary complexes of certain hydroxylacids and their biological applicationsrdquo Research Journal ofPharmaceutical Biological and Chemical Sciences vol 5 no 4pp 18ndash30 2014
[34] N N Greenwood and A Earnshaw A Review of Chemistry ofthe Elements Pergamon Press Oxford UK 1984
[35] V Reddy N Patil and S D Angadi ldquoSynthesis character-ization and antimicrobial activity of Cu(II) Co(II) and Ni(II)complexes with ON and S Donor ligandsrdquo E-Journal ofChemistry vol 5 no 3 pp 577ndash583 2008
[36] F A Cotton G Wilkinson C A Murillo et al Advances inSchiff Base Chemistry Wiley New York NY USA 6th edi-tion 1999
[37] M M H Khalil E H Ismail S A Azim and E R SouayaldquoSynthesis characterization and thermal analysis of ternarycomplexes of nitrilotriacetic acid and alanine or phenylala-nine with some transition metalsrdquo Journal of +ermalAnalysis and Calorimetry vol 101 no 1 pp 129ndash135 2010
[38] F Mabbs and D Colisson Electron Paramagnetic Resonanceof D Transition Metal Compounds Vol 102 ElsevierAmsterdam Netherlands 1992
[39] M M H Khalil E R Souaya E H Ismail et al ldquoTernarytransition metal complexes of nitrilotriacetic acid and valineor leucine synthesis and biological applicationsrdquo ChineseJournal of Inorganic Chemistry vol 29 no 9 pp 1969ndash19782013
[40] I M Weiss C Muth R Drumm and H O K Kirchnerldquo(ermal decomposition of the amino acids glycine cysteineaspartic acid asparagine glutamic acid glutamine arginineand histidinerdquo BMC Biophysics vol 11 no 1 2018
[41] A M Petrosyan V V Ghazaryan G Giester and M FleckldquoSulfamates and methanesulfonates of L-arginine and L-his-tidinerdquo Journal of Molecular Structure vol 1163 pp 114ndash1272018
Journal of Chemistry 17
[42] T Kavitha S Haider T Kamal and M Ul-Islam ldquo(ermaldecomposition of metal complex precursor as route to thesynthesis of Co3O4 nanoparticles antibacterial activity andmechanismrdquo Journal of Alloys and Compounds vol 704pp 296ndash302 2017
[43] E M M Ibrahim L H Abdel-Rahman A M Abu-DiefA Elshafaie S K Hamdan and A M Ahmed ldquo(e synthesisof CuO andNiO nanoparticles by facile thermal decompositionof metal-Schiff base complexes and an examination of theirelectric thermoelectric and magnetic Propertiesrdquo MaterialsResearch Bulletin vol 107 pp 492ndash497 2018
[44] S Farhadi M Javanmard and G Nadri ldquoCharacterization ofcobalt oxide nanoparticles prepared by the thermal de-compositionrdquo Acta Chimica Slovenica vol 63 pp 335ndash3432016
[45] E M Zayed E H Ismail G G Mohamed M M H Khaliland A B Kamel ldquoSynthesis spectroscopic and structuralcharacterization and antimicrobial studies of metal com-plexes of a new hexadentate Schiff base ligand Spectropho-tometric determination of Fe(III) in water samples using arecovery testrdquo Monatshefte fur Chemie-Chemical Monthlyvol 145 no 5 pp 755ndash765 2014
[46] V Milacic D Chen L Ronconi K R Landis-PiwowarD Fregona and Q P Dou ldquoA novel anticancer gold(III)dithiocarbamate compound inhibits the activity of a purified20S proteasome and 26S proteasome in human breast cancercell cultures and xenograftsrdquo Cancer Research vol 66 no 21pp 10478ndash10486 2006
[47] T Mosmann ldquoRapid colorimetric assay for cellular growthand survival application to proliferation and cytotoxicityassaysrdquo Journal of Immunological Methods vol 65 no 1-2pp 55ndash63 1983
[48] R L Siegel K D Miller and A Jemal ldquoCancer statistics2018rdquo CA A Cancer Journal for Clinicians vol 68 no 1pp 7ndash30 2018
[49] S Chattopadhyay S P Chakraborty D Laha et al ldquoSurface-modified cobalt oxide nanoparticles new opportunities foranti-cancer drug developmentrdquo Cancer Nanotechnol vol 3no 1-6 pp 13ndash23 2012
[50] F Zielinski V Tognetti and L Joubert ldquoCondensed de-scriptors for reactivity a methodological studyrdquo ChemicalPhysics Letters vol 527 pp 67ndash72 2012
[51] H Wang Y He Q Yan et al ldquoCorrelation between thedielectric properties and biological activities of human ex vivohepatic tissuerdquo Physics in Medicine and Biology vol 60 no 6pp 2603ndash2617 2015
[52] F Tao F Fu F You et al ldquo(e correlation between dielectricproperties and microstructure of femoral bone in rats withdifferent bone qualitiesrdquo Annals of Biomedical Engineeringvol 42 no 6 pp 1238ndash1249 2014
[53] L Gun D Ning and Z Liang ldquoEffective permittivity ofbiological tissue comparison of theoretical model and ex-perimentrdquo Mathematical Problems in Engineering vol 2017Article ID 7249672 2017
[54] E I Ating S A Umoren I I Udousoro E E Ebenso andA P Udoh ldquoLeaves extract of Ananas sativumas greencorrosion inhibitor for aluminium in hydrochloric acid so-lutionsrdquo Green Chemistry Letters and Reviews vol 3 no 2pp 61ndash68 2010
[55] E Hamed ldquoStudies of the corrosion inhibition of copper inNa2SO4 solution using polarization and electrochemicalimpedance spectroscopyrdquo Materials Chemistry and Physicsvol 121 no 1-2 pp 70ndash76 2010
[56] H Zarrok H Oudda A Zarrouk et al ldquoWeight loss mea-surement and theoretical study of new pyridazine compoundas corrosion inhibitor for C38 steel in hydrochloric acidsolutionrdquo Der Pharma Chemica vol 3 no 6 pp 576ndash5902011
18 Journal of Chemistry
TribologyAdvances in
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
International Journal ofInternational Journal ofPhotoenergy
Hindawiwwwhindawicom Volume 2018
Journal of
Chemistry
Hindawiwwwhindawicom Volume 2018
Advances inPhysical Chemistry
Hindawiwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2018
Bioinorganic Chemistry and ApplicationsHindawiwwwhindawicom Volume 2018
SpectroscopyAnalytical ChemistryInternational Journal of
Hindawiwwwhindawicom Volume 2018
MaterialsJournal of
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
BioMed Research International Electrochemistry
International Journal of
Hindawiwwwhindawicom Volume 2018
Na
nom
ate
ria
ls
Hindawiwwwhindawicom Volume 2018
Journal ofNanomaterials
Submit your manuscripts atwwwhindawicom
and the slope for the straight line of the relation betweenln(RcorrT) vs (1T) respectively N is Avogadrorsquos numberand h is Planckrsquos constant (e Gibbs free energy of acti-vation ∆Glowast can be detected by equation (9)
ΔGlowast ΔHlowast minusTΔSlowast (9)
Table 9 shows the thermodynamic parameters for theadsorption of mixed ligands and their metal complexes (epositive value of ∆Hlowast indicated the endothermic property ofdissolution process nature for aluminum in the acidicmedium [54]
However the blank ΔHlowast value is higher than the in-hibitor metal complexes which indicated that the inhibitionefficiency generally increases with increasing temperature(e association step is the rate-determining step rather thana dissociation process in presence of the metal complexesinhibitors due to the negative values of ΔSlowast It is known thatthe values of ΔGlowast above 40 kJmiddotmolminus1 are referred to chargetransfer from the inhibitor molecules into aluminum surfaceto form coordinated compound on the Al surface whichblocks it against corrosion process by different degrees Alsothe chemical adsorption process mechanism is confirmed bythe values of ΔGlowast above 40 kJmiddotmolminus1 [16 54ndash56]
4 Conclusions
Novel coordination materials of ternary divalent metalions (Cu(II) Ni(II) Co(II) and Zn(II)) chelated by thebidentate glutamic acid (Glu) and L-arginine (Arg) aminoacids are synthesized and characterized (e metal ionscomplexes are modelled using density DFT and TD-DFTtheory Computed molecular and spectroscopic (IR UV-Vis and EPR) properties validated the experimental re-sults (e used computational methods are capable ofproviding good structural descriptions for the TM com-plexes Consistent with the experimental properties theoptimized structures of the complexes [Cu(II) Glu-Arg]and [Co(II) Glu-Arg (H2O)2] reveal that symmetry en-vironment of Cu(II) exhibits slightly distorted squareplanar shape whereas Co(II)-complex has a distortedoctahedral (where Co(II) central ion is of C4v-localsymmetry) Spectral properties of [Ni(II) Glu-Arg(H2O)2] and [ZnmiddotGlumiddotArgmiddot(H2O)2] complexes indicatethat they have similar structure as Co(II) complex All thestudied ternary metal complexes are of different anti-fungal activities ranging from moderate to weak withoutpractically noticed inhibitory effects whereas antibacte-rial activities of all studied metal complexes show sig-nificant effects
Cytotoxicity studies against (HePG2) reveal the prom-ising potentiality of Cu(II) complex as inhibitor of cancercells(e results are correlated with the computed moleculardescriptors including dipole moment polarizability ther-modynamics and reactivity properties as well as the PESmaps
(e corrosion inhibition of aluminum metal specimensin 1M HCl is efficiently achieved by mixed ligands and theirmetal complexes studied
Data Availability
(e data used to support the findings of this study areavailable from the corresponding author upon request
Conflicts of Interest
(e authors declare that they have no conflicts of interest
Supplementary Materials
(e supplementary materials consist of six figures and twotables to further clarify the structures and trends of the newlyprepared metal ternary complexes (SupplementaryMaterials)
References
[1] Z Ozturk D A Kose A Asan et al ldquoPorous metal-organicCu(II) complex of L-Arginine 2synthesis characterizationhydrogen storage properties and molecular simulation cal-culationsrdquo Hittite Journal of Science and Engineering vol 1no 1 pp 1ndash5 2014
[2] S A Lahsasni R A Ammar M F Amin et al ldquoMixed-ligandcomplex formation of Cu(II) with 12- diphenylethylenedi-amine as primary ligand and amino acids as secondary li-gandsrdquo International Journal of Electrochemical Sciencevol 7 pp 7699ndash7711 2012
[3] H Sigel B P Operschall S S Massoud B Song andR Griesser ldquoEvidence for intramolecular aromatic-ringstacking in the physiological pH range of the mono-deprotonated xanthine residue in mixed-ligand complexescontaining xanthosinate 5prime-monophosphate (XMP)rdquo DaltonTransactions vol 46 no 46 pp 5521ndash5529 2006
[4] S Udhayakumar K G Shankar S Sowndarya S VenkateshC Muralidharan and C Rose ldquol-Arginine intercedes bio-crosslinking of a collagen-chitosan 3D-hybrid scaffold fortissue engineering and regeneration in silico in vitro and invivo studiesrdquo RSC Advances vol 7 no 40 pp 25070ndash250882017
[5] P K Datta M Chandra and A K Dey ldquoTernary complexesof copper(II) nickel(II) and zinc(II) with nitrilotriacetic acidas a primary ligand and some phenolic acids as secondaryligandsrdquo Transition Metal Chemistry vol 5 no 1ndash3 1980
[6] J S Woertink L Tian D Maiti et al ldquoSpectroscopic andcomputational studies of an end-on bound superoxo-Cu(II)complex geometric and electronic factors that determine theground staterdquo Inorganic Chemistry vol 49 no 20pp 9450ndash9459 2010
[7] S Dutta S Ray K Nagarajan et al ldquoGlutamic acid analoguesused as potent anticancer a reviewrdquo Der Pharma Chemicavol 3 no 2 pp 263ndash272 2011
[8] T Sismanoglu S Pura and A Bastug ldquoBinary and ternarymetal complexes of Congo red with amino acidsrdquo Dyes andPigments vol 70 no 2 pp 136ndash142 2006
[9] R N Patel H C Pandey K B Pandeya et al ldquoMixed ligandcomplex formation of nickel(II)copper(II) and zinc(II) withsome amino acids and imidazolesrdquo Indian Journal ofChemistry-Section A Inorganic Physical +eoretical andAnalytical Chemistry vol 38 no 8 pp 850ndash853 1999
[10] L Meng and Z Lin ldquoComplexations of alkalialkaline earthmetal cations with gaseous glutamic acidrdquo Computational and+eoretical Chemistry vol 1039 pp 1ndash10 2014
16 Journal of Chemistry
[11] L D Pinto P A L Puppin V M Behring O C AlvesN A Rey and J Felcman ldquoSolution and solid state study ofcopper(II) ternary complexes containing amino acids of in-terest for brain biochemistry-2 homocysteine with aspartateglutamate or methioninerdquo Inorganica Chimica Acta vol 386pp 60ndash67 2012
[12] A Wojciechowska A Ggor and W Zierkiewicz ldquoChiraloctahedral complexes of Co(III) as catalysts for asymmetricepoxidation of chalcones under phase transfer conditionsrdquoRSC Advances vol 5 no 46 pp 36295ndash36306 2015
[13] B M Weckhuysen A A Verberckmoes L Fu andR A Schoonheydt ldquoZeolite-encapsulated copper(II) aminoacid complexes synthesis spectroscopy and catalysisrdquo Journalof Physical Chemistry vol 100 no 22 pp 9456ndash9461 1996
[14] K Y El-Baradie N A El-Wakiel and H A El-GhamryldquoSynthesis characterization and corrosion inhibition in acidmedium ofl-histidine Schiff base complexesrdquo Applied Or-ganometallic Chemistry vol 29 no 3 pp 117ndash125 2015
[15] S S R Anthony and R Susai ldquoInhibition of corrosion ofcarbon steel in well water by arginine-Zn2+ systemrdquo Journal ofElectrochemical Science and Engineering vol 2 no 2pp 91ndash104 2012
[16] E H Isamil F F AlBlewi N Soliman and M M H Khalilldquo(ermal studies and mass loss inhibition for some newmixed amino acid metal complexes with their applicationsrdquoJournal of +ermal Analysis and Calorimetry vol 125 no 1pp 289ndash300 2016
[17] F Neese ldquo(e ORCA program system 4012rdquo Wiley In-terdisciplinary Reviews Computational Molecular Sciencevol 2 no 1 pp 73ndash78 2012
[18] S Grimme S Ehrlich and L Goerigk ldquoEffect of the dampingfunction in dispersion corrected density functional theoryrdquoJournal of Computational Chemistry vol 32 no 7pp 1456ndash1465 2011
[19] S Grimme J Antony S Ehrlich and H Krieg ldquoA consistentand accurate ab initio parametrization of density functionaldispersion correction (DFT-D) for the 94 elements H-Purdquo+e Journal of Chemical Physics vol 132 no 15 article154104 2010
[20] F Weigend ldquoHartree-Fock exchange fitting basis sets for H toRnrdquo Journal of Computational Chemistry vol 29 no 2pp 167ndash175 2008
[21] F Neese F Wennmohs and A Hansen ldquoEfficient ap-proximate and parallel Hartree-Fock and hybrid DFT cal-culations A lsquochain-of-spheresrsquo algorithm for the Hartree-Fock exchangerdquo Chemical Physics vol 356 no 1ndash3pp 98ndash109 2009
[22] R Izsak and F Neese ldquoAn overlap fitted chain of spheresexchange methodrdquo Journal of Chemical Physics vol 135no 14 article 144105 2011
[23] T Petrenko S Kossmann and F Neese ldquoEfficient time-dependent density functional theory approximations forhybrid density functionals analytical gradients and paralle-lizationrdquo Journal of Chemical Physics vol 134 no 5 article054116 2011
[24] A V Marenich C J Cramer and D G Truhlar ldquoUniversalsolvation model based on solute electron density and on acontinuum model of the solvent defined by the bulk dielectricconstant and atomic surface tensionsrdquo Journal of PhysicalChemistry B vol 113 no 18 pp 6378ndash96 2009
[25] S Donovan C Stiefbold and K Sprague ldquoChapter 3Chemical properties of amino acids and identification ofunknown amino acidsrdquo in Proceedings of the 17 thWorkshopConference of the Association for Biology
Laboratory Education (ABLE) vol 17 pp 35ndash70 Bain-bridge GA USA March 1996
[26] C C Wagner J Enrique and C Claudia ldquoVibrational andmagnetic properties of a CuMg glutamate complexrdquoArgentina Acta Farm Bonaerense vol 22 no 2 pp 137ndash1422003
[27] M Arif R Sur and M Arshad ldquoStudies on the thermaldecomposition of copper (II) flouride complexes with variousamino acids in nitrogen atmosphererdquo Turkish Journal ofChemistry vol 25 pp 73ndash79 2001
[28] A Ghosh M J Tucker and R M Hochstrasser ldquoIdentifi-cation of arginine residues in peptides by 2d-IR echo spec-troscopyrdquo Journal of Physical Chemistry A vol 115 no 34pp 9731ndash9738 2011
[29] K Nakamoto Infrared Spectra of Inorganic and CoordinationCompounds Part B Wiley-Interscience New York NY USA5th edition 1997
[30] E Santi M H Torre E Kremer S B Etcheverry andE J Baran ldquoVibrational spectra of the copper(II) and nick-el(II) complexes of piroxicamrdquo Vibrational Spectroscopyvol 5 no 3 pp 285ndash293 1993
[31] H N Aliyu and A S Mohammed ldquoSynthesis spectropho-tometric and biological activity of nickel (II) and copper (II)complexes with schiff base derived from acetylacetone andhistidinerdquo Global Advanced Research Journal of Microbiologyvol 1 no 5 pp 67ndash71 2012
[32] J S Murray and P Politzer ldquo(e electrostatic potential anoverviewrdquo Wiley Interdisciplinary Reviews ComputationalMolecular Science vol 1 no 2 pp 153ndash163 2011
[33] E R Souaya M M H Khalil and E H Ismail ldquoSynthesis andcharacterization of ternary complexes of certain hydroxylacids and their biological applicationsrdquo Research Journal ofPharmaceutical Biological and Chemical Sciences vol 5 no 4pp 18ndash30 2014
[34] N N Greenwood and A Earnshaw A Review of Chemistry ofthe Elements Pergamon Press Oxford UK 1984
[35] V Reddy N Patil and S D Angadi ldquoSynthesis character-ization and antimicrobial activity of Cu(II) Co(II) and Ni(II)complexes with ON and S Donor ligandsrdquo E-Journal ofChemistry vol 5 no 3 pp 577ndash583 2008
[36] F A Cotton G Wilkinson C A Murillo et al Advances inSchiff Base Chemistry Wiley New York NY USA 6th edi-tion 1999
[37] M M H Khalil E H Ismail S A Azim and E R SouayaldquoSynthesis characterization and thermal analysis of ternarycomplexes of nitrilotriacetic acid and alanine or phenylala-nine with some transition metalsrdquo Journal of +ermalAnalysis and Calorimetry vol 101 no 1 pp 129ndash135 2010
[38] F Mabbs and D Colisson Electron Paramagnetic Resonanceof D Transition Metal Compounds Vol 102 ElsevierAmsterdam Netherlands 1992
[39] M M H Khalil E R Souaya E H Ismail et al ldquoTernarytransition metal complexes of nitrilotriacetic acid and valineor leucine synthesis and biological applicationsrdquo ChineseJournal of Inorganic Chemistry vol 29 no 9 pp 1969ndash19782013
[40] I M Weiss C Muth R Drumm and H O K Kirchnerldquo(ermal decomposition of the amino acids glycine cysteineaspartic acid asparagine glutamic acid glutamine arginineand histidinerdquo BMC Biophysics vol 11 no 1 2018
[41] A M Petrosyan V V Ghazaryan G Giester and M FleckldquoSulfamates and methanesulfonates of L-arginine and L-his-tidinerdquo Journal of Molecular Structure vol 1163 pp 114ndash1272018
Journal of Chemistry 17
[42] T Kavitha S Haider T Kamal and M Ul-Islam ldquo(ermaldecomposition of metal complex precursor as route to thesynthesis of Co3O4 nanoparticles antibacterial activity andmechanismrdquo Journal of Alloys and Compounds vol 704pp 296ndash302 2017
[43] E M M Ibrahim L H Abdel-Rahman A M Abu-DiefA Elshafaie S K Hamdan and A M Ahmed ldquo(e synthesisof CuO andNiO nanoparticles by facile thermal decompositionof metal-Schiff base complexes and an examination of theirelectric thermoelectric and magnetic Propertiesrdquo MaterialsResearch Bulletin vol 107 pp 492ndash497 2018
[44] S Farhadi M Javanmard and G Nadri ldquoCharacterization ofcobalt oxide nanoparticles prepared by the thermal de-compositionrdquo Acta Chimica Slovenica vol 63 pp 335ndash3432016
[45] E M Zayed E H Ismail G G Mohamed M M H Khaliland A B Kamel ldquoSynthesis spectroscopic and structuralcharacterization and antimicrobial studies of metal com-plexes of a new hexadentate Schiff base ligand Spectropho-tometric determination of Fe(III) in water samples using arecovery testrdquo Monatshefte fur Chemie-Chemical Monthlyvol 145 no 5 pp 755ndash765 2014
[46] V Milacic D Chen L Ronconi K R Landis-PiwowarD Fregona and Q P Dou ldquoA novel anticancer gold(III)dithiocarbamate compound inhibits the activity of a purified20S proteasome and 26S proteasome in human breast cancercell cultures and xenograftsrdquo Cancer Research vol 66 no 21pp 10478ndash10486 2006
[47] T Mosmann ldquoRapid colorimetric assay for cellular growthand survival application to proliferation and cytotoxicityassaysrdquo Journal of Immunological Methods vol 65 no 1-2pp 55ndash63 1983
[48] R L Siegel K D Miller and A Jemal ldquoCancer statistics2018rdquo CA A Cancer Journal for Clinicians vol 68 no 1pp 7ndash30 2018
[49] S Chattopadhyay S P Chakraborty D Laha et al ldquoSurface-modified cobalt oxide nanoparticles new opportunities foranti-cancer drug developmentrdquo Cancer Nanotechnol vol 3no 1-6 pp 13ndash23 2012
[50] F Zielinski V Tognetti and L Joubert ldquoCondensed de-scriptors for reactivity a methodological studyrdquo ChemicalPhysics Letters vol 527 pp 67ndash72 2012
[51] H Wang Y He Q Yan et al ldquoCorrelation between thedielectric properties and biological activities of human ex vivohepatic tissuerdquo Physics in Medicine and Biology vol 60 no 6pp 2603ndash2617 2015
[52] F Tao F Fu F You et al ldquo(e correlation between dielectricproperties and microstructure of femoral bone in rats withdifferent bone qualitiesrdquo Annals of Biomedical Engineeringvol 42 no 6 pp 1238ndash1249 2014
[53] L Gun D Ning and Z Liang ldquoEffective permittivity ofbiological tissue comparison of theoretical model and ex-perimentrdquo Mathematical Problems in Engineering vol 2017Article ID 7249672 2017
[54] E I Ating S A Umoren I I Udousoro E E Ebenso andA P Udoh ldquoLeaves extract of Ananas sativumas greencorrosion inhibitor for aluminium in hydrochloric acid so-lutionsrdquo Green Chemistry Letters and Reviews vol 3 no 2pp 61ndash68 2010
[55] E Hamed ldquoStudies of the corrosion inhibition of copper inNa2SO4 solution using polarization and electrochemicalimpedance spectroscopyrdquo Materials Chemistry and Physicsvol 121 no 1-2 pp 70ndash76 2010
[56] H Zarrok H Oudda A Zarrouk et al ldquoWeight loss mea-surement and theoretical study of new pyridazine compoundas corrosion inhibitor for C38 steel in hydrochloric acidsolutionrdquo Der Pharma Chemica vol 3 no 6 pp 576ndash5902011
18 Journal of Chemistry
TribologyAdvances in
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
International Journal ofInternational Journal ofPhotoenergy
Hindawiwwwhindawicom Volume 2018
Journal of
Chemistry
Hindawiwwwhindawicom Volume 2018
Advances inPhysical Chemistry
Hindawiwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2018
Bioinorganic Chemistry and ApplicationsHindawiwwwhindawicom Volume 2018
SpectroscopyAnalytical ChemistryInternational Journal of
Hindawiwwwhindawicom Volume 2018
MaterialsJournal of
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
BioMed Research International Electrochemistry
International Journal of
Hindawiwwwhindawicom Volume 2018
Na
nom
ate
ria
ls
Hindawiwwwhindawicom Volume 2018
Journal ofNanomaterials
Submit your manuscripts atwwwhindawicom
[11] L D Pinto P A L Puppin V M Behring O C AlvesN A Rey and J Felcman ldquoSolution and solid state study ofcopper(II) ternary complexes containing amino acids of in-terest for brain biochemistry-2 homocysteine with aspartateglutamate or methioninerdquo Inorganica Chimica Acta vol 386pp 60ndash67 2012
[12] A Wojciechowska A Ggor and W Zierkiewicz ldquoChiraloctahedral complexes of Co(III) as catalysts for asymmetricepoxidation of chalcones under phase transfer conditionsrdquoRSC Advances vol 5 no 46 pp 36295ndash36306 2015
[13] B M Weckhuysen A A Verberckmoes L Fu andR A Schoonheydt ldquoZeolite-encapsulated copper(II) aminoacid complexes synthesis spectroscopy and catalysisrdquo Journalof Physical Chemistry vol 100 no 22 pp 9456ndash9461 1996
[14] K Y El-Baradie N A El-Wakiel and H A El-GhamryldquoSynthesis characterization and corrosion inhibition in acidmedium ofl-histidine Schiff base complexesrdquo Applied Or-ganometallic Chemistry vol 29 no 3 pp 117ndash125 2015
[15] S S R Anthony and R Susai ldquoInhibition of corrosion ofcarbon steel in well water by arginine-Zn2+ systemrdquo Journal ofElectrochemical Science and Engineering vol 2 no 2pp 91ndash104 2012
[16] E H Isamil F F AlBlewi N Soliman and M M H Khalilldquo(ermal studies and mass loss inhibition for some newmixed amino acid metal complexes with their applicationsrdquoJournal of +ermal Analysis and Calorimetry vol 125 no 1pp 289ndash300 2016
[17] F Neese ldquo(e ORCA program system 4012rdquo Wiley In-terdisciplinary Reviews Computational Molecular Sciencevol 2 no 1 pp 73ndash78 2012
[18] S Grimme S Ehrlich and L Goerigk ldquoEffect of the dampingfunction in dispersion corrected density functional theoryrdquoJournal of Computational Chemistry vol 32 no 7pp 1456ndash1465 2011
[19] S Grimme J Antony S Ehrlich and H Krieg ldquoA consistentand accurate ab initio parametrization of density functionaldispersion correction (DFT-D) for the 94 elements H-Purdquo+e Journal of Chemical Physics vol 132 no 15 article154104 2010
[20] F Weigend ldquoHartree-Fock exchange fitting basis sets for H toRnrdquo Journal of Computational Chemistry vol 29 no 2pp 167ndash175 2008
[21] F Neese F Wennmohs and A Hansen ldquoEfficient ap-proximate and parallel Hartree-Fock and hybrid DFT cal-culations A lsquochain-of-spheresrsquo algorithm for the Hartree-Fock exchangerdquo Chemical Physics vol 356 no 1ndash3pp 98ndash109 2009
[22] R Izsak and F Neese ldquoAn overlap fitted chain of spheresexchange methodrdquo Journal of Chemical Physics vol 135no 14 article 144105 2011
[23] T Petrenko S Kossmann and F Neese ldquoEfficient time-dependent density functional theory approximations forhybrid density functionals analytical gradients and paralle-lizationrdquo Journal of Chemical Physics vol 134 no 5 article054116 2011
[24] A V Marenich C J Cramer and D G Truhlar ldquoUniversalsolvation model based on solute electron density and on acontinuum model of the solvent defined by the bulk dielectricconstant and atomic surface tensionsrdquo Journal of PhysicalChemistry B vol 113 no 18 pp 6378ndash96 2009
[25] S Donovan C Stiefbold and K Sprague ldquoChapter 3Chemical properties of amino acids and identification ofunknown amino acidsrdquo in Proceedings of the 17 thWorkshopConference of the Association for Biology
Laboratory Education (ABLE) vol 17 pp 35ndash70 Bain-bridge GA USA March 1996
[26] C C Wagner J Enrique and C Claudia ldquoVibrational andmagnetic properties of a CuMg glutamate complexrdquoArgentina Acta Farm Bonaerense vol 22 no 2 pp 137ndash1422003
[27] M Arif R Sur and M Arshad ldquoStudies on the thermaldecomposition of copper (II) flouride complexes with variousamino acids in nitrogen atmosphererdquo Turkish Journal ofChemistry vol 25 pp 73ndash79 2001
[28] A Ghosh M J Tucker and R M Hochstrasser ldquoIdentifi-cation of arginine residues in peptides by 2d-IR echo spec-troscopyrdquo Journal of Physical Chemistry A vol 115 no 34pp 9731ndash9738 2011
[29] K Nakamoto Infrared Spectra of Inorganic and CoordinationCompounds Part B Wiley-Interscience New York NY USA5th edition 1997
[30] E Santi M H Torre E Kremer S B Etcheverry andE J Baran ldquoVibrational spectra of the copper(II) and nick-el(II) complexes of piroxicamrdquo Vibrational Spectroscopyvol 5 no 3 pp 285ndash293 1993
[31] H N Aliyu and A S Mohammed ldquoSynthesis spectropho-tometric and biological activity of nickel (II) and copper (II)complexes with schiff base derived from acetylacetone andhistidinerdquo Global Advanced Research Journal of Microbiologyvol 1 no 5 pp 67ndash71 2012
[32] J S Murray and P Politzer ldquo(e electrostatic potential anoverviewrdquo Wiley Interdisciplinary Reviews ComputationalMolecular Science vol 1 no 2 pp 153ndash163 2011
[33] E R Souaya M M H Khalil and E H Ismail ldquoSynthesis andcharacterization of ternary complexes of certain hydroxylacids and their biological applicationsrdquo Research Journal ofPharmaceutical Biological and Chemical Sciences vol 5 no 4pp 18ndash30 2014
[34] N N Greenwood and A Earnshaw A Review of Chemistry ofthe Elements Pergamon Press Oxford UK 1984
[35] V Reddy N Patil and S D Angadi ldquoSynthesis character-ization and antimicrobial activity of Cu(II) Co(II) and Ni(II)complexes with ON and S Donor ligandsrdquo E-Journal ofChemistry vol 5 no 3 pp 577ndash583 2008
[36] F A Cotton G Wilkinson C A Murillo et al Advances inSchiff Base Chemistry Wiley New York NY USA 6th edi-tion 1999
[37] M M H Khalil E H Ismail S A Azim and E R SouayaldquoSynthesis characterization and thermal analysis of ternarycomplexes of nitrilotriacetic acid and alanine or phenylala-nine with some transition metalsrdquo Journal of +ermalAnalysis and Calorimetry vol 101 no 1 pp 129ndash135 2010
[38] F Mabbs and D Colisson Electron Paramagnetic Resonanceof D Transition Metal Compounds Vol 102 ElsevierAmsterdam Netherlands 1992
[39] M M H Khalil E R Souaya E H Ismail et al ldquoTernarytransition metal complexes of nitrilotriacetic acid and valineor leucine synthesis and biological applicationsrdquo ChineseJournal of Inorganic Chemistry vol 29 no 9 pp 1969ndash19782013
[40] I M Weiss C Muth R Drumm and H O K Kirchnerldquo(ermal decomposition of the amino acids glycine cysteineaspartic acid asparagine glutamic acid glutamine arginineand histidinerdquo BMC Biophysics vol 11 no 1 2018
[41] A M Petrosyan V V Ghazaryan G Giester and M FleckldquoSulfamates and methanesulfonates of L-arginine and L-his-tidinerdquo Journal of Molecular Structure vol 1163 pp 114ndash1272018
Journal of Chemistry 17
[42] T Kavitha S Haider T Kamal and M Ul-Islam ldquo(ermaldecomposition of metal complex precursor as route to thesynthesis of Co3O4 nanoparticles antibacterial activity andmechanismrdquo Journal of Alloys and Compounds vol 704pp 296ndash302 2017
[43] E M M Ibrahim L H Abdel-Rahman A M Abu-DiefA Elshafaie S K Hamdan and A M Ahmed ldquo(e synthesisof CuO andNiO nanoparticles by facile thermal decompositionof metal-Schiff base complexes and an examination of theirelectric thermoelectric and magnetic Propertiesrdquo MaterialsResearch Bulletin vol 107 pp 492ndash497 2018
[44] S Farhadi M Javanmard and G Nadri ldquoCharacterization ofcobalt oxide nanoparticles prepared by the thermal de-compositionrdquo Acta Chimica Slovenica vol 63 pp 335ndash3432016
[45] E M Zayed E H Ismail G G Mohamed M M H Khaliland A B Kamel ldquoSynthesis spectroscopic and structuralcharacterization and antimicrobial studies of metal com-plexes of a new hexadentate Schiff base ligand Spectropho-tometric determination of Fe(III) in water samples using arecovery testrdquo Monatshefte fur Chemie-Chemical Monthlyvol 145 no 5 pp 755ndash765 2014
[46] V Milacic D Chen L Ronconi K R Landis-PiwowarD Fregona and Q P Dou ldquoA novel anticancer gold(III)dithiocarbamate compound inhibits the activity of a purified20S proteasome and 26S proteasome in human breast cancercell cultures and xenograftsrdquo Cancer Research vol 66 no 21pp 10478ndash10486 2006
[47] T Mosmann ldquoRapid colorimetric assay for cellular growthand survival application to proliferation and cytotoxicityassaysrdquo Journal of Immunological Methods vol 65 no 1-2pp 55ndash63 1983
[48] R L Siegel K D Miller and A Jemal ldquoCancer statistics2018rdquo CA A Cancer Journal for Clinicians vol 68 no 1pp 7ndash30 2018
[49] S Chattopadhyay S P Chakraborty D Laha et al ldquoSurface-modified cobalt oxide nanoparticles new opportunities foranti-cancer drug developmentrdquo Cancer Nanotechnol vol 3no 1-6 pp 13ndash23 2012
[50] F Zielinski V Tognetti and L Joubert ldquoCondensed de-scriptors for reactivity a methodological studyrdquo ChemicalPhysics Letters vol 527 pp 67ndash72 2012
[51] H Wang Y He Q Yan et al ldquoCorrelation between thedielectric properties and biological activities of human ex vivohepatic tissuerdquo Physics in Medicine and Biology vol 60 no 6pp 2603ndash2617 2015
[52] F Tao F Fu F You et al ldquo(e correlation between dielectricproperties and microstructure of femoral bone in rats withdifferent bone qualitiesrdquo Annals of Biomedical Engineeringvol 42 no 6 pp 1238ndash1249 2014
[53] L Gun D Ning and Z Liang ldquoEffective permittivity ofbiological tissue comparison of theoretical model and ex-perimentrdquo Mathematical Problems in Engineering vol 2017Article ID 7249672 2017
[54] E I Ating S A Umoren I I Udousoro E E Ebenso andA P Udoh ldquoLeaves extract of Ananas sativumas greencorrosion inhibitor for aluminium in hydrochloric acid so-lutionsrdquo Green Chemistry Letters and Reviews vol 3 no 2pp 61ndash68 2010
[55] E Hamed ldquoStudies of the corrosion inhibition of copper inNa2SO4 solution using polarization and electrochemicalimpedance spectroscopyrdquo Materials Chemistry and Physicsvol 121 no 1-2 pp 70ndash76 2010
[56] H Zarrok H Oudda A Zarrouk et al ldquoWeight loss mea-surement and theoretical study of new pyridazine compoundas corrosion inhibitor for C38 steel in hydrochloric acidsolutionrdquo Der Pharma Chemica vol 3 no 6 pp 576ndash5902011
18 Journal of Chemistry
TribologyAdvances in
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
International Journal ofInternational Journal ofPhotoenergy
Hindawiwwwhindawicom Volume 2018
Journal of
Chemistry
Hindawiwwwhindawicom Volume 2018
Advances inPhysical Chemistry
Hindawiwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2018
Bioinorganic Chemistry and ApplicationsHindawiwwwhindawicom Volume 2018
SpectroscopyAnalytical ChemistryInternational Journal of
Hindawiwwwhindawicom Volume 2018
MaterialsJournal of
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
BioMed Research International Electrochemistry
International Journal of
Hindawiwwwhindawicom Volume 2018
Na
nom
ate
ria
ls
Hindawiwwwhindawicom Volume 2018
Journal ofNanomaterials
Submit your manuscripts atwwwhindawicom
[42] T Kavitha S Haider T Kamal and M Ul-Islam ldquo(ermaldecomposition of metal complex precursor as route to thesynthesis of Co3O4 nanoparticles antibacterial activity andmechanismrdquo Journal of Alloys and Compounds vol 704pp 296ndash302 2017
[43] E M M Ibrahim L H Abdel-Rahman A M Abu-DiefA Elshafaie S K Hamdan and A M Ahmed ldquo(e synthesisof CuO andNiO nanoparticles by facile thermal decompositionof metal-Schiff base complexes and an examination of theirelectric thermoelectric and magnetic Propertiesrdquo MaterialsResearch Bulletin vol 107 pp 492ndash497 2018
[44] S Farhadi M Javanmard and G Nadri ldquoCharacterization ofcobalt oxide nanoparticles prepared by the thermal de-compositionrdquo Acta Chimica Slovenica vol 63 pp 335ndash3432016
[45] E M Zayed E H Ismail G G Mohamed M M H Khaliland A B Kamel ldquoSynthesis spectroscopic and structuralcharacterization and antimicrobial studies of metal com-plexes of a new hexadentate Schiff base ligand Spectropho-tometric determination of Fe(III) in water samples using arecovery testrdquo Monatshefte fur Chemie-Chemical Monthlyvol 145 no 5 pp 755ndash765 2014
[46] V Milacic D Chen L Ronconi K R Landis-PiwowarD Fregona and Q P Dou ldquoA novel anticancer gold(III)dithiocarbamate compound inhibits the activity of a purified20S proteasome and 26S proteasome in human breast cancercell cultures and xenograftsrdquo Cancer Research vol 66 no 21pp 10478ndash10486 2006
[47] T Mosmann ldquoRapid colorimetric assay for cellular growthand survival application to proliferation and cytotoxicityassaysrdquo Journal of Immunological Methods vol 65 no 1-2pp 55ndash63 1983
[48] R L Siegel K D Miller and A Jemal ldquoCancer statistics2018rdquo CA A Cancer Journal for Clinicians vol 68 no 1pp 7ndash30 2018
[49] S Chattopadhyay S P Chakraborty D Laha et al ldquoSurface-modified cobalt oxide nanoparticles new opportunities foranti-cancer drug developmentrdquo Cancer Nanotechnol vol 3no 1-6 pp 13ndash23 2012
[50] F Zielinski V Tognetti and L Joubert ldquoCondensed de-scriptors for reactivity a methodological studyrdquo ChemicalPhysics Letters vol 527 pp 67ndash72 2012
[51] H Wang Y He Q Yan et al ldquoCorrelation between thedielectric properties and biological activities of human ex vivohepatic tissuerdquo Physics in Medicine and Biology vol 60 no 6pp 2603ndash2617 2015
[52] F Tao F Fu F You et al ldquo(e correlation between dielectricproperties and microstructure of femoral bone in rats withdifferent bone qualitiesrdquo Annals of Biomedical Engineeringvol 42 no 6 pp 1238ndash1249 2014
[53] L Gun D Ning and Z Liang ldquoEffective permittivity ofbiological tissue comparison of theoretical model and ex-perimentrdquo Mathematical Problems in Engineering vol 2017Article ID 7249672 2017
[54] E I Ating S A Umoren I I Udousoro E E Ebenso andA P Udoh ldquoLeaves extract of Ananas sativumas greencorrosion inhibitor for aluminium in hydrochloric acid so-lutionsrdquo Green Chemistry Letters and Reviews vol 3 no 2pp 61ndash68 2010
[55] E Hamed ldquoStudies of the corrosion inhibition of copper inNa2SO4 solution using polarization and electrochemicalimpedance spectroscopyrdquo Materials Chemistry and Physicsvol 121 no 1-2 pp 70ndash76 2010
[56] H Zarrok H Oudda A Zarrouk et al ldquoWeight loss mea-surement and theoretical study of new pyridazine compoundas corrosion inhibitor for C38 steel in hydrochloric acidsolutionrdquo Der Pharma Chemica vol 3 no 6 pp 576ndash5902011
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