61

[3.1] INSTRUMENTS AND EXPERIMENTAL PARAMETERS:

INSTRUMENTS:

SPECTROPHOTOMETER:

The absorbance measurements were done on a "Milton Roy"

(Spectronic-20D+) Spectrophotometer and "Abotta make UV-1100, UV-Visible

Spectrophotometer". The IR spectra were recorded on "Perkin-Elmer" FTIR

Spectrophotometer (RX-1) in KBr pallet. The NMR spectra were recorded on

"Bruker Avance II 400 NMR Spectrometer.

pH METER:

The pH of the solutions were measured on Equip-Tronic pH meter (Model

No. EQ 614) and solutions of required pH were obtained using sodium acetate-

acetic acid, sodium acetate-HCl, NH3-NH4Cl or Borax-HCl buffer of suitable

concentrations.

TEMPERATURE:

All the experiments, including the preparation of the solutions, extraction of

the complex, recording the observation etc. were carried out at room

temperature.

MATERIALS:

All chemicals used throughout this work were of analytical grade.

EFFECT OF TIME ON THE ABSORBANCE OF THE CHELATE:

The colour development due to the formation of metal chelates was found

to attain constancy in absorbance values within five minutes and were found to

be constant for sufficient long period. Details for each chelate is given with the

study of respective chelate.

62

EFFECT OF ORDER OF ADDITION OF THE REAGENT:

The effect of order of addition of the reagent was observed in all

experiments. It is found that the order of addition of the reagent had no effect.

However in alkaline conditions, it was necessary to add reagent first and buffer

afterwards, to prevent precipitation of metal hydroxides.

NUMBER OF COMPLEX SPECIES FORMED:

In order to ascertain the number of complexes formed in each case, under

the experimental conditions, the method of W.C. Vosburgh and G.R. Cooper

[208] was employed. Several mixtures containing metal ion and the ligand in the

ratio 1:1, 1:2, 1:3 and 1:4 were prepared at selected pH. The absorbances of the

solutions were measured between a selected range of wavelength. In second

experiment, several mixtures containing stoichiometry amount of metal ion and

ligand were prepared at different pH values and the absorbance of the complexes

were measured. By the number of shifts in the region of maximum absorbance of

the mixtures from the max of the reagent itself, the number of complexes formed

was ascertained. During the studies, it was found that only one complex was

formed in all cases under the experimental conditions.

DETERMINATION OF CONDITIONAL STABILITY CONSTANT:

The conditional stability constant for the complexes were determined from

Yoe and Jone's mole ratio method and Job's method of continuous variation. The

Gibb's free energy change Go for the complex formation reactions were also

calculated.

ANALYTICAL APPLICATIONS OF THE METAL CHELATES:

BEER'S LAW:

The obeyance of the Beer law was studied for the metal chelates under

investigation by varying metal ion concentrations and adding the excess reagent

in constant amount and measuring the absorbance at wavelength of maximum

absorbance and at pH where maximum complex formation occurs. The range of

63

concentration for obeyance to the Beer law expressed in ppm for each system

has been determined from the graph.

MOLAR ABSORPTIVITY:

The values of molar absorptivities were calculated for all complexes. The

values of molar absorptivities are expressed in lit.mole-1.cm-1.

[3.2] PREPARATION OF SOLUTIONS AND SYNTHESIS OF

REAGENT:

Preparation of Metal Ion Solutions:

Four metal salts,

(i) FeCl3 (Anhydrous) : (M.Wt. = 162.21)

(ii) PdCl2 : (M.Wt. = 177.21)

(v) CuSO4.5H2O : (M.Wt. = 249.68)

(vi) NiSO4.6H2O : (M.Wt. = 262.71)

were used for the present work.

All the metal salts except PdCl2 are soluble in water. Stock solutions of all

the salts were prepared by dissolving the requisite amount of salts in doubly

distilled water. A little free acid was added to prevent hydrolysis. Solutions of

desired concentrations were obtained by suitable dilution of stock solutions. In

case of PdCl2, requisite quantity was first dissolved in few mL concentrated HCl

and then diluted with water.

* SYNTHESIS OF REAGENTS:

The detailed experimental procedure for the synthesis of the reagents are

given below:

[A] 2'-HYDROXY-4'-BUTOXYCHALCONE OXIME :

(i) RESACETOPHENONE FROM RESORCINOL:

It was prepared from resorcinol, glacial acetic acid and anhydrous zinc

chloride according to the method of R. Robinson and R.C. Shah [165].

Resorcinol Acetic acid Resacetophenone

HO OH OHHO

C=O

CH3

+ CH3COOHAnhy.

ZnCl2

64

(ii) 2-HYDROXY-4-BUTOXYACETOPHENONE:

Resacetophenone (15.2 g, 0.1 mole), n-butyl bromide (13.7 g, 0.1 mole),

and anhydrous potassium carbonate (13.81 g, 0.1 mole) in acetone was refluxed

on a water bath at 65-700C for six hours. The mixture was then poured over

crushed ice and acidified with diluted HCl. The solid separated was filtered out,

washed with water, dried and crystallized from ethanol. Light yellow crystals

obtained, m.p. 65oC.

OHOH

C = O

CH3

OHC4H

9O

C = O

CH3

n-butyl bromide

Resacetophenone 2-Hydroxy-4-butoxy-

acetophenone

(iii) 2'-HYDROXY-4'-BUTOXYCHALCONE:

To a solution of 2-hydroxy-4-butoxyacetophenone (10.4 g, 0.05 mole) and

benzaldehyde (5.3 g, 0.05 mole) in ethanol (20 ml), aqueous solution of KOH (20

ml, 40%) was added dropwise with vigorous stirring and the flask was cooled

under the cold water tap so as to keep the reaction temperature 20-25oC. The

colour of the reaction mixture changed. The flask was tightly corked and was kept

at room temperature for 18 hours. The content was then poured over crushed ice

and acidified with dilute HCl. The solid separated was filtered out, washed with

water, dried and crystallised from benzene. Light orange crystals obtained,

m.p.135oC. Yield is 70 %.

OH

C = O

C4H

9O OH

C = O

C4H

9O

CHO

CH3

CH = CH

+Alcoholic

KOH

2-Hydroxy-4- Benzaldehyde 2'-Hydroxy-4'-butoxy

butoxyacetophenone chalcone

65

(iv) 2'-HYDROXY-4'-BUTOXYCHALCONE OXIME (HBCO):

The oxime was prepared by sodium acetate method. 2'-Hydroxy-4'-

butoxychalcone (2.0 gm) was dissolved in minimum quantity of ethanol. Aqueous

solutions of hydroxylamine hydrochloride (4.0 gm) and sodium acetate (6.0 gm)

were added to it. A little more alcohol was added to get clear solution. The

solution was refluxed on a water-bath at 75-80oC for four hours. The mixture was

poured on crushed ice with stirring, when light yellow oxime separated. It was

crystallised from ethanol (yield 1.5 gm), light yellow coloured crystals were

obtained, m.p. 178oC.

OH

C = O

C4H

9O

CH = CH

OH

C - CH = CH

C4H

9O

NH2OH.HCl

[CH3COONa]

N - OH

2'-Hydroxy-4'-butoxychalcone 2'-Hydroxy-4'-butoxychalcone

oxime (HBCO)

[B] 2'-HYDROXY-4'-METHOXYCHALCONE OXIME:

(i) RESACETOPHENONE FROM RESORCINOL :

It was prepared as described earlier.

(ii) 2-HYDROXY-4-METHOXYACETOPHENONE:

Resacetophenone (15.2 g, 0.1 mole), methyl iodide (14.19 g, 0.1 mole),

and anhydrous potassium carbonate (13.81 g, 0.1 mole) in acetone was refluxed

on a water bath at 65-700C for six hours. The mixture was then poured over

crushed ice and acidified with diluted HCl. The solid separated was filtered out,

washed with water, dried and crystallized from ethanol. Light yellow crystals

obtained, m.p. 45oC.

OHOH

C = O

CH3

OHCH3O

C = O

CH3

methyl iodide

Resacetophenone 2-Hydroxy-4-methoxy acetophenone

66

(iii) 2'-HYDROXY-4'-METHOXYCHALCONE:

To a solution of 2-hydroxy-4-methoxyacetophenone (8.3 g, 0.05 mole) and

benzaldehyde (5.3 g, 0.05 mole) in ethanol (20 ml), aqueous solution of KOH (20

ml, 40%) was added dropwise with vigorous stirring and the flask was cooled

under the cold water tap so as to keep the reaction temperature 20-25oC. The

colour of the reaction mixture changed. The flask was tightly corked and was kept

at room temperature for 18 hours. The content was then poured over crushed ice

and acidified with dilute HCl. The solid separated was filtered out, washed with

water, dried and crystallised from benzene. Light orange crystals obtained,

m.p.85oC. Yield is 70 %.

OH

C = O

CH3O OH

C = O

CH3O

CHO

CH3

CH = CH

+Alcoholic

KOH

2-Hydroxy-4- Benzaldehyde 2'-Hydroxy-4'-methoxy methoxyacetophenone chalcone (iv) 2'-HYDROXY-4'-METHOXYCHALCONE OXIME (HMCO):

The oxime was prepared by sodium acetate method. 2'-Hydroxy-4'-

methoxychalcone (2.0 gm) was dissolved in minimum quantity of ethanol.

Aqueous solutions of hydroxylamine hydrochloride (4.0 gm) and sodium acetate

(6.0 gm) were added to it. A little more alcohol was added to get clear solution.

The solution was refluxed on a water-bath at 75-80oC for four hours. The mixture

was poured on crushed ice with stirring, when light yellow oxime separated. It

was crystallised from ethanol (yield 1.5 gm), light yellow coloured crystals were

obtained, m.p. 142oC.

OH

C = O

CH3O

CH = CH

OH

C - CH = CH

CH3O

NH2OH.HCl

[CH3COONa]

N - OH

2'-Hydroxy-4'-methoxychalcone 2'-Hydroxy-4'-methoxychalcone

oxime (HMCO)

67

[C] 2-HYDROXY-4-METHOXYACETOPHENONE THIOSEMICARBAZONE:

(i) RESACETOPHENONE FROM RESORCINOL :

It was prepared as described earlier.

(ii) 2-HYDROXY-4-METHOXYACETOPHENONE:

It was prepared as described earlier.

(iii) 2-HYDROXY-4-METHOXYACETOPHENONE THIOSEMICARBAZONE:

A mixture of 2-hydroxy-4-methoxyacetophenone (2.0g), thiosemicarbazide

(2.0 g) in ethanol (30.0 ml) and glacial acetic acid (6.0ml) was refluxed on a

waterbath for four hours. The mixture was then poured in ice-cold water when

pale yellow coloured 2-hydroxy-4-methoxyacetophenone thiosemicarbazone was

separated. It was filtered, washed and crystallized from alcohol,pale yellow

crystals, insoluble in water, soluble in ethanol, m.p. 1660C.

OHCH3O

C = O

CH3

OHCH3O

C = N - N - C - NH2

CH3

H SS

NH2NH-C-NH

2

CH3COOH

2-Hydroxy-4-methoxy 2-Hydroxy-4-methoxyacetophenone thio-

acetophenone semicarbazone (HMAT)

PREPARATION OF REAGENT SOLUTION:

The reagents HBCO, HMCO & HMAT are soluble in 70% aqueous ethanol.

Reagent solutions were prepared by dissolving requisite amount in ethanol and

diluted to final volume so as to keep final concentration of ethanol 70%. The

reagent solutions were found to be stable for long time and could be kept for

months after preparation.

REACTIVITY OF LIGAND:

A 0.02 M solution of reagents were employed for checking its reactivity with

aqueous solution of metal ions at different pH values.

68

ANALYSIS OF REAGENT:

These reagents were analysed for its carbon, hydrogen and nitrogen

content. The percentage of these elements found are in agreement with their

molecular formula. The results are given in the following table:

Reagent Molecular formula

% Found (Calculated)

Carbon Hydrogen Nitrogen Sulphur

2'-Hydroxy-4'-butoxychalcone oxime (HBCO)

C19H21O3N 73.51 (73.31)

6.63 (6.75)

4.68 (4.50)

-

2'-Hydroxy-4'-methoxychalcone oxime (HMCO)

C16H16O3N 69.35 (71.11)

5.44 (5.92)

5.17 (5.19)

-

2-Hydroxy-4-methoxyacetophenone thio-

semicarbazone (HMAT)

C10H13O2N3S 44.86 (50.20)

4.83 (5.43)

14.35 (17.57)

23.40 (13.38)

UV-VISIBLE SPECTRA OF REAGENTS:

The UV-Visible spectra of reagents HBCO, HMCO and HMAT in ethanol

were recorded on "Systronics make, UV-Visible Spectrophotometer". The graph

is shown in figure-3.1(I), 3.1(II) and 3.1(III) respectively.

Reagent Molecular formula

max

2'-Hydroxy-4'-butoxychalcone oxime (HBCO)

C19H21O3N 250 nm

2'-Hydroxy-4'-methoxychalcone oxime (HMCO)

C16H15O3N 330 nm

2-Hydroxy-4-methoxyacetophenone thio semicarbazone (HMAT)

C10H13O2N3S 350 nm

69

ABSORPTION SPECTRA OF LIGAND HBCO

Fig. 3.1 (I)

ABSORPTION SPECTRA OF LIGAND HMCO

Fig. 3.1 (II)

70

ABSORPTION SPECTRA OF LIGAND HMAT

Fig. 3.1 (III)

71

IR SPECTRA OF LIGAND HBCO :

The important absorption bands are assigned. The spectra are given along

with the IR spectra of complexes.

Band Assignment

3200 to 3700 with peak

at 3400 cm-1

phenolic -OH

oximino -OH obscured by phenolic -OH

3000 cm-1 aromatic C-H stretching

2925 cm-1 aliphatic C-H stretching

1596 cm-1 C=N stretching

1525 cm-1 CH=CH stretching

NMR SPECTRA OF LIGAND HBCO :

It was taken on "BRUKER" NMR Spectrometer. Different signals are

assigned as follows.

OH

C - CH = CH

C4H

9O

N - OH

2'-Hydroxy-4'-butoxychalcone oxime (HBCO)

Chemical shift Assignment

1.004

1.284

1.520

1.779

protons of n-butoxy group

4.00 proton of oximino -OH

6.56 & 6.61 -CH=CH- protons

6.84 to 7.66 aromatic protons

7.87 phenolic -OH proton

72

IR SPECTRA OF LIGAND HBCO

Fig. 3.1 (IV)

NMR SPECTRA OF LIGAND HBCO

Fig. 3.1 (V)

73

IR SPECTRA OF LIGAND HMCO :

The important absorption bands are assigned. The spectra are given along

with the IR spectra of complexes.

Band Assignment

3429 cm-1

3200 cm-1

oximino -OH obscured by phenolic -OH

phenolic -OH broad band

3066 cm-1 aromatic C-H stretching

2924 cm-1 aliphatic C-H stretching

1510 cm-1 C=N stretching

1621 cm-1

1282 cm-1

CH=CH stretching

C=O stretching in phenol

961 cm-1 N-OH stretching

1165 cm-1 C-O stretching in ether

1521 cm-1 C=C stretching

NMR SPECTRA OF LIGAND HMCO :

It was taken on "BRUKER" NMR Spectrometer. Different signals are

assigned as follows.

OH

C - CH = CH

CH3O

N - OH

2'-Hydroxy-4'-methoxychalcone oxime (HMCO)

Chemical shift Assignment

3.769

3.794

3.802

protons of n-methoxy group

10.88 proton of oximino -OH

7.7 & 7.9 -CH=CH- protons

6.00 to 7.5 aromatic protons

10.44 proton of phenolic -OH

74

IR SPECTRA OF LIGAND HMCO

Fig. 3.1 (VI)

12 11 10 9 8 7 6 5 4 3 2 1 0 ppm

0.0000

1.2460

2.1182

2.2428

2.5441

2.5482

2.5519

2.6032

2.6330

2.6459

2.6755

3.3549

3.3766

3.3849

3.4197

3.4276

3.7177

3.7349

3.7375

3.7606

3.7694

3.7811

3.7940

3.8029

5.1039

6.3574

6.3637

6.4822

6.4881

6.5154

6.5226

6.5283

6.5446

6.5501

6.6087

6.6146

7.1073

7.1995

7.2462

7.2646

7.2849

7.3184

7.3322

7.3429

7.3627

7.3836

7.3974

7.4029

7.4204

7.4618

7.4763

7.4949

7.5093

7.5166

7.7257

7.7345

7.7477

7.7563

7.8590

7.8621

7.8775

7.8817

8.0818

9.8900

10.4482

10.8848

0.25

1.61

2.00

0.48

1.22

0.60

1.00

2.68

2.36

0.85

1.18

0.55

0.25

Current Data Parameters

NAME May03-2013

EXPNO 530

PROCNO 1

F2 - Acquisition Parameters

Date_ 20130504

Time 10.57

INSTRUM spect

PROBHD 5 mm PABBO BB-

PULPROG zg30

TD 65536

SOLVENT DMSO

NS 8

DS 2

SWH 12019.230 Hz

FIDRES 0.183399 Hz

AQ 2.7263477 sec

RG 362

DW 41.600 usec

DE 6.00 usec

TE 292.8 K

D1 1.00000000 sec

TD0 1

======== CHANNEL f1 ========

NUC1 1H

P1 10.90 usec

PL1 -3.00 dB

SFO1 400.1324710 MHz

F2 - Processing parameters

SI 32768

SF 400.1299845 MHz

WDW EM

SSB 0

LB 0.30 Hz

GB 0

PC 1.00

ABRUKER

AVANCE II 400 NMR

Spectrometer

SAIFPanjab University

Chandigarh

avtar_saifpu@yahoo.co.in

NMR SPECTRA OF LIGAND HMCO

Fig. 3.1 (VII)

RC SAIF PU, Chandigarh

Spectrum Name: Limbachiya-1.sp Description: A

Date Created: thu may 16 13:03:15 2013 India Standard Time (GMT+5:30)

4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600 450.0

33.0

34

36

38

40

42

44

46

48

50

52

54

56

58

60

62.4

cm-1

%T

3429

3066

2964

2924

2841

1881

1621

1574

1521

1510

1470

1448

1422

1405

1333

1282

1260

1246

1209

1165

1124

1059

1045

1030

1003

961

918

863

844

830

796

765

736

698

684

631

576

536

459

75

IR SPECTRA OF LIGAND HMAT :

The important absorption bands are assigned. The spectra are given along

with the IR spectra of complexes.

Band Assignment

3380 cm-1 phenolic -OH

1593 cm-1, 1621 cm-1 aromatic ring skeleton

2841 cm-1 aliphatic C-H stretching

1509 cm-1 C=N stretching

1484 cm-1 C=S stretching

3148 - 3265 cm-1 Symm. and asymm. stretching of -NH2 & N-H

str. (doublet)

1252 cm-1 C-O stretching of phenol

1000 - 1100 cm-1 C-O-C stretching of ether

2998 cm-1 aromatic C-H str.

NMR SPECTRA OF LIGAND HMAT :

It was taken on "BRUKER" NMR Spectrometer. Different signals are

assigned as follows.

OHCH3O

C = N - N - C - NH2

CH3

H S

2-Hydroxy-4-methoxyacetophenone thiosemicarbazone (HMAT)

Chemical shift Assignment

3.779 protons of n-methoxy group

12.60 proton of phenolic -OH

3.4065 protons of NH2 & NH

6.5 to 8.00 aromatic protons

9.720 proton of phenolic -OH

11.5676 -NH group

1.96 - 2.55 protons of -CH3 group

76

IR SPECTRA OF LIGAND HMAT

Fig. 3.1 (VIII)

14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 ppm

0.0000

1.2471

1.8924

1.9433

1.9632

2.1208

2.2213

2.3155

2.5149

2.5578

3.4065

3.7793

3.8279

3.8331

6.3995

6.4049

6.4158

6.4214

6.4377

6.4435

6.4592

6.4654

6.4821

6.4878

6.5475

6.5527

6.9970

7.0161

7.0373

7.1250

7.2537

7.3506

7.3977

7.4193

7.5203

7.7295

7.7516

7.9331

8.0291

8.0634

9.7201

9.7846

10.6347

11.5676

12.6709

12.9855

0.61

2.55

0.20

0.21

2.84

3.00

2.07

0.12

0.15

0.20

0.68

1.43

0.58

0.68

0.38

0.19

0.08

0.75

0.49

0.28

0.65

Current Data Parameters

NAME May03-2013

EXPNO 540

PROCNO 1

F2 - Acquisition Parameters

Date_ 20130504

Time 11.03

INSTRUM spect

PROBHD 5 mm PABBO BB-

PULPROG zg30

TD 65536

SOLVENT DMSO

NS 8

DS 2

SWH 12019.230 Hz

FIDRES 0.183399 Hz

AQ 2.7263477 sec

RG 512

DW 41.600 usec

DE 6.00 usec

TE 292.9 K

D1 1.00000000 sec

TD0 1

======== CHANNEL f1 ========

NUC1 1H

P1 10.90 usec

PL1 -3.00 dB

SFO1 400.1324710 MHz

F2 - Processing parameters

SI 32768

SF 400.1299796 MHz

WDW EM

SSB 0

LB 0.30 Hz

GB 0

PC 1.00

BBRUKER

AVANCE II 400 NMR

Spectrometer

SAIFPanjab University

Chandigarh

avtar_saifpu@yahoo.co.in

NMR SPECTRA OF LIGAND HMAT

Fig. 3.1 (IX)

RC SAIF PU, Chandigarh

Spectrum Name: Limbachiya-2.sp Description: B

Date Created: thu may 16 13:04:29 2013 India Standard Time (GMT+5:30)

4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600 450.0

12.0

14

16

18

20

22

24

26

28

30

32

34

36

38

40

42

44

46

48.5

cm-1

%T

3380

3265

3148

2998

2960

2841

2061

1874

1621

1593 1509

1484

1469

1440

1374

1342

1252

1234

1200

1170

1152

1135

1088

1043

1022

973

947

866

839

792

753

721

593

528

494

470

457