Robust Aluminium and Iron Phosphinate Metal-Organic ...

doi.org/10.26434/chemrxiv.11584458.v1

Robust Aluminium and Iron Phosphinate Metal-Organic Frameworks forEfficient Removal of Bisphenol ADaniel Bužek, Soňa Ondrušová, Jan Hynek, Petr Kovář, Kamil Lang, Jan Rohlíček, Jan Demel

Submitted date: 12/01/2020 • Posted date: 13/01/2020Licence: CC BY-NC-ND 4.0Citation information: Bužek, Daniel; Ondrušová, Soňa; Hynek, Jan; Kovář, Petr; Lang, Kamil; Rohlíček, Jan; etal. (2020): Robust Aluminium and Iron Phosphinate Metal-Organic Frameworks for Efficient Removal ofBisphenol A. ChemRxiv. Preprint. https://doi.org/10.26434/chemrxiv.11584458.v1

Herein, we introduce a new series of highly stable MOFs, constructed using Fe3+ and Al3+ metal ions andbisphosphinate linkers. The isoreticular design leads to ICR-2, ICR-4, ICR-6, and ICR-7 MOFs with ahoneycomb arrangement of linear pores, surface areas up to 1360 m2 g-1, and high solvothermal stability. Inmost cases, their sorption capacity is retained even after 24 h reflux in water. The choice of the linkers allowsfine tuning of the pore sizes and the chemical nature of the pores. This feature can be utilized for optimizationof host-guest interactions between molecules and pore walls. Water pollution by various endocrine disruptingchemicals has been considered as a global threat to public health. In this work, we proved that the chemicalstability and the hydrophobic nature of the synthesized series of MOFs result in remarkable sorptionproperties of these materials for neurodisruptor bisphenol A.

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Robust Aluminium and Iron Phosphinate Metal Organic Frameworks for Efficient Removal of Bisphenol A

Daniel Bůžek,a,b Soňa Ondrušová,a Jan Hynek,a Petr Kovář,c Kamil Lang,a Jan Rohlíček,d Jan De-mela*

a Institute of Inorganic Chemistry of the Czech Academy of Sciences, 250 68 Husinec-Řež, Czech Republic; E-mail:

[email protected] b

Faculty of Environment, Jan Evangelista Purkyně University, Králova Výšina 3132/7, 400 96 Ústí nad Labem, Czech Republic c Charles University, Faculty of Mathematics and Physics, Ke Karlovu 3, 121 16, Praha 2, Czech Republic

d Institute of Physics of the Czech Academy of Sciences, 182 21 Praha, Czech Republic

ABSTRACT: Porous metal–organic frameworks (MOFs) have excellent characteristics for the adsorptive removal of envi-ronmental pollutants. Herein, we introduce a new series of highly stable MOFs, constructed using Fe3+ and Al3+ metal ions and bisphosphinate linkers. The isoreticular design leads to ICR-2, ICR-4, ICR-6, and ICR-7 MOFs with a honeycomb arrangement of linear pores, surface areas up to 1360 m2 g-1, and high solvothermal stability. In most cases, their sorption capacity is retained even after 24 h reflux in water. The choice of the linkers allows fine tuning of the pore sizes and the chemical nature of the pores. This feature can be utilized for optimization of host-guest interactions between molecules and pore walls. Water pollution by various endocrine disrupting chemicals has been considered as a global threat to pub-lic health. In this work, we proved that the chemical stability and the hydrophobic nature of the synthesized series of MOFs result in remarkable sorption properties of these materials for neurodisruptor bisphenol A.

INTRODUCTION

Endocrine disrupting chemicals are gaining increased attention among emerging pollutants due to their influ-ence on endocrine system by mimicking or blocking natu-ral hormones, or over/under production of specific hor-mones.1 This diverse group of pollutants is utilized in broad spectrum of human products such as herbicides (DDT, Propanil), antimicrobial agents (Triclosan), deter-gents, toiletries, cosmetics (parabens, phenols), pharma-ceutics (diethystilbestrol), and plastics (phthalates, bi-sphenol A, brominated flame retardants).1,2 The most studied endocrine disruptor is bisphenol A (2,2-bis(4-hydroxyphenyl)propane; BPA). Over a million tons per year of BPA is produced mainly for the production of plastics such as polycarbonate and epoxy resins. It was found that BPA can leach from the products (e.g., bever-age containers and packages, baby bottles, dental seal-ants), migrate into the environment, and enter the food chain.2-4 Therefore, methods for fast and effective removal of BPA from waste water or landfill leachate are of great importance. Commonly used sorbents, such as activated charcoal, zeolites, or clays have low affinity toward BPA or low sorption capacity.5,6 For these reasons, new materi-als have to be developed in order to stop spreading endo-crine disruptors in the environment.

Metal-organic frameworks (MOFs) belong to the fast growing area of organic-inorganic hybrids. MOFs are

combining metal nodes (secondary building units - SBUs) and polytopic organic ligands (linkers).7 The number of possible SBUs and organic linkers gives rise to thousands of new structures with varying topologies, pore sizes, and chemical compositions.8-10 The high surface area of MOFs,11,12 along with the possibility of introducing func-tional groups,13,14 make them highly promising materials for many applications,15 including sorbents of pollu-tants.16-18 Unfortunately even after decades of extensive research, water stability of MOFs still remains an issue,19 thus limiting their applicability for waste water treatment.

Recently, we have demonstrated that the combination of Fe3+ ions with bisphosphinate linker H2PBP(Me) (Fig-ure 1) leads to a new MOF, named Fe-ICR-2 (ICR stands for Inorganic Chemistry Řež), with a honeycomb struc-ture.20 Importantly, Fe-ICR-2 is endowed with higher hydrothermal stability in comparison with a carboxylate-based analogue Fe-MIL-53.21 The stability is related to the stronger coordination bond of phosphinates to hard met-als, such as Fe3+, in comparison with carboxylate groups. Notably, the methyl group bound at phosphorus atom is pointing into the volume of the Fe-ICR-2 pore. Substitu-tion with bulkier phenyl group leads to decrease in the pore size (Fe-ICR-4),20 suggesting that this strategy can allow for fine-tuning of pore hydrophobicity.

In this work, we applied the reticular design and ex-tended the bisphosphinate linkers. We synthesized and

delineated the properties of a series of phosphinate MOFs denoted ICR-2, ICR-4, ICR-6, and ICR-7 in both Fe3+ and Al3+ versions (Figure 1). All prepared MOFs possess the honeycomb arrangement of linear pores with sizes vary-ing from 3 Å to 24 Å. The hydrophobic nature of the pores leads to the high sorption capacity for BPA.

RESULTS AND DISCUSSION

The solvothermal reaction of bisphosphinate linkers (Figure 1, bottom-left) with FeCl3·6 H2O or AlCl3·6 H2O in EtOH at 250 °C yielded crystalline ICR MOFs. The only exception was the reaction of H2BBP(Me) with FeCl3·6 H2O which led to a nonporous layered material Fe-ICR-5. In this case, the synthetic conditions were optimized and porous Fe-ICR-6 was obtained in DMF at 120 °C after three-day reaction. However, Fe-ICR-6 is of inferior crys-tallinity due to lower temperature used when compared with other ICR MOFs (see below). The composition of all synthesised MOFs is given in Table 1 and is confirmed by elemental analyses and FTIR spectra (Table S1, Figures S1-S7).

The thermal stability of ICR MOFs in air was investigat-ed by thermogravimetric analyses in conjunction with differential thermal analyses and mass spectroscopy (TGA/DTA/MS) (Figures S8-S14). The TGA curves indi-cate that all prepared ICR MOFs are endowed with high thermal stability and contain negligible amount of solvent or water molecules inside the pores. The least stable is Al-ICR-4 which starts to decompose at 350 °C, whereas Al-ICR-7 is the most thermally stable ICR MOF with decom-position temperature of 550 °C.

The crystal structure of Fe-ICR-7 was obtained from powder X-ray diffraction (PXRD) data (Table S2). The indexing was performed in the DICVOL06 program22 and the crystal structure models were found ab initio using the FOX software (detailed description is in the Support-ing Information.23 The final Rietveld fit confirms the pro-posed structure (Table S2, Figure S16). The low crystallini-ty of Fe-ICR-6 did not allow indexing of the PXRD pat-tern. Nevertheless, the isoreticular design of ICR MOFs and solved structures of Fe-ICR-2 and Fe-ICR-420 enabled

creation of a structural model followed by geometry op-timization using the PCFF force field and the Rietveld refinement in the Materials Studio software (Figure S18).24 The PXRD patterns of all Fe-ICR MOFs are compared in Figure 1, bottom-middle.

Motivated by successful syntheses of Fe-ICR MOFs, we investigated the structural arrangements of aluminium-based ICR MOFs (Al-ICR MOFs). In the case of Al-ICR-4, the quality of the PXRD pattern allowed solving the crys-tal structure ab initio using the Superflip package25 with the histogram matching option (Figure S17). The detailed analysis of the corresponding PXRD pattern confirms nearly identical crystal structure of Al-ICR-4 with that of Fe-ICR-420 (Table S2). In general, the analyses of PXRD patterns of Al-ICR MOFs revealed that they form identical structural motifs for each linker with those of Fe-ICR MOFs (Figure S20).

As illustrated for Fe-ICR MOFs (Figure 1, middle),20 the secondary building units (SBUs) of Fe-ICR MOFs and Al-ICR MOFs (not applicable for Fe-ICR-5, see below for details) are composed of octahedrally coordinated metal atoms bound together through O-P-O bridges forming one-dimensional (1D) infinity columns. The columns are connected via phenylene or biphenylene bridges forming the three-dimensional (3D) honeycomb framework. Fe- and Al- versions of ICR-6 and ICR-7 are isoreticular struc-tures to Fe-ICR-2 with increased pore sizes due to the incorporated biphenylene spacer. The crystal structures of Fe-ICR-4 and Al-ICR-4 are constructed similarly to the structure of Fe-ICR-2, i.e., the honeycomb arrangement is composed of 1D infinity columns tied together by O-P-O bridges. However, the phenylene groups connecting the 1D columns are not parallel to each other, but they are crossed and rotated in neighbouring layers (Figure 1 left).

Figure 1. Honeycomb patterns of 1D pores of Fe-ICR MOFs running along the c-axis (top), the pore limiting diameter (nm) cal-culated by Poreblazer is indicated in the middle of the pore; 1D columns of octahedrally coordinated iron atoms bridged by phosphinate acid groups (middle), ICR MOFs coding (bottom-left), PXRD of Fe-ICR MOFs (bottom-middle), and adsorption isotherms of nitrogen for Fe-ICR MOFs (bottom-right). Colour coding: octahedrally coordinated iron atoms (blue), phosphinate tetrahedra (magenta), O (red), C (grey), and H (white).

The crystal structure of Fe-ICR-5 was also solved from PXRD data in this work (Table S2, Figure S15). Its struc-ture is layered, composed of 1D infinity columns of iron atoms coordinated by O-P-O bridges (Figure S19). In this case, oxygen atoms are coordinated to Fe3+ centres in a trigonal bipyramid formation and every two neighbouring bipyramids are edge-sharing. In the chain, the pairs of edge-shared bipyramids are connected through vertices by four phosphinate tetrahedrons. The chains form bi-layers that are held together only by weak nonbonding interactions. This structural arrangement is isoreticular to Fe-ICR-3.20 Comparison of both structures is given in Figure S19. Since Fe-ICR-5 is nonporous this material was not further investigated.

The permanent porosity of activated ICR MOFs was probed by measurement of N2 adsorption isotherms at 77 K (Figure 1, bottom-right and Figure S43). All adsorption isotherms display a steep N2 uptake at low P/P0 ratios which is typical for microporous materials. More specifi-cally, ICR-4 contains ultramicropores, whereas the pore diameters of ICR-6 and ICR-7 are at the borderline be-tween micropores and mesopores (Table 1 and Figures S21-24).

To better understand the porous structure of ICR MOFs, these MOFs were computationally analysed using the Poreblazer software26,27 for N2 molecule with 3.314 Å in diameter (Table 1). The obtained parameters for Fe-ICR-2 and Al-ICR-2 are in agreement with the experimental values. The calculated pore limiting diameters (PLD) of Fe-ICR-4 and Al-ICR-4 are of 2.9 Å; therefore, the accessi-ble surface area cannot be calculated. Nevertheless, the pores are still accessible to N2 as evidenced by the corre-sponding adsorption isotherms (Figure 1, bottom-right and Figure S43). The BET specific surface areas of Fe-ICR-7 and Al-ICR-7 fit well the calculated values, whereas in the case of Fe-ICR-6 and Al-ICR-6 the BET specific sur-face areas are considerably lower, probably due to lower crystallinity and/or pore blocking. The PLDs of Fe-ICR-6 and Al-ICR-6 and Fe-ICR-7 and Al-ICR-7 are considerably smaller than pore diameters obtained by the NLDFT method from adsorption isotherms. This difference can be caused by roughness of pore walls decreasing the smallest opening of the pores, and/or by the hydrophobic nature of the pores significantly differing from the chemi-cal nature used by the kernel in the NLDFT method.

0.0 0.5 1.0

0

200

400

600

800

1000

Vc

m3 (

ST

P)

g-1

p / p0

Fe-ICR-2

Fe-ICR-4

Fe-ICR-6

Fe-ICR-7

4 8 12 16 20 24 28 32 36 40

10 20 30Fe-ICR-7

Fe-ICR-6

Inte

nsit

y /

a.u

.

2 Theta / °

Fe-ICR-2

Fe-ICR-4

Table 1. Specific surface area, pore diameter, calculated pore limiting diameter, and accessible surface area for all synthetized MOFs

Sample Linker

Specific Surface area

Area

[m2 g-

1]

Pore Diameter

[nm]a

Pore Volume [cm

3 g

-1]

b

Pore Limiting Diameter

[nm]c

Accessible Surface Area

[m2 g

-1]

d

Pore Accessible Volume [cm

3 g

-1]

e

Fe-ICR-2 H2PBP(Me) 906 f 0.71 0.39 0.90 850 0.48

Fe-ICR-4 H2PBP(Ph) 165 f n.a. 0.044 0.29 0 n.a.

Fe-ICR-6 H2BBP(Me) 1134 g

2.39 1.32 1.75 1562 1.00

Fe-ICR-7 H2BBP(Ph) 1125 g

2.16 0.79 1.32 1097 0.64

Al-ICR-2 H2PBP(Me) 933 f 0.74 0.44 0.90 876 0.48

Al-ICR-4 H2PBP(Ph) 190 f n.a. 0.055 0.29 0 n.a.

Al-ICR-6 H2BBP(Me) 1362 g

2.34 1.59 1.75 1660 1.06

Al-ICR-7 H2BBP(Ph) 1030 g

2.07 1.52 1.31 1088 0.63

a Pore diameter obtained by the MP plot for ICR-2 and ICR-4, otherwise by the NLDFT method;

b Total pore volume;

c Pore

limiting diameter calculated by the Poreblazer software; d Accessible surface area calculated by the Poreblazer software;

e Acces-

sible pore volume calculated by the Poreblazer software; f Specific surface area calculated by the t-plot;

g BET specific surface

area.

Synthesized ICR MOFs are expected to be chemically stable under harsh conditions as described previously for Fe-ICR-2.20 After treatment of ICR MOFs in water, EtOH, and toluene at RT or under reflux, the PXRD patterns of most of ICR MOFs remained unchanged, suggesting preservation of the crystallinity and original structure (Figures S25-S42). Only Fe-ICR-6, Al-ICR-6, and Al-ICR-7 recrystallized or lost crystallinity in boiling water. Gener-ally, the longer the linker, the lower is the stability of MOFs. For example, UiO-66 built of the terephthalate linker is stable in water and under humid atmosphere, however, both UiO-67 and UiO-68 made of biphenyl-4,4′-dicarboxylate and p-terphenyl-4,4″-dicarboxylate linkers, respectively, decompose when exposed to humid air.28 This behaviour is not the case of presented ICR MOFs.

We also analysed the effects of these treatments on specific surface area (Table 2, Figures S44-S61), except for Fe-ICR-4 and Al-ICR-4. In these two cases, small mole-cules, such as water, block the pores and are not removed even during activation (150°C, vacuum, 24h), while keep-ing the PXRD patterns intact. Fe-ICR-2, Al-ICR-2, Fe-ICR-6, Fe-ICR-7, and Al-ICR-7 retained their porosity in the tested solvents at RT, in boiling toluene, and with the exception of Fe-ICR-2 in boiling EtOH. Interestingly, Al-

ICR-6 behaves differently. The specific surface area de-creased after the solvent treatments at RT, whereas the treatment in boiling EtOH or toluene resulted in an in-crease of the specific surface area, probably due to the formation of structural defects. In general, boiling water represents one of the most challenging condition for MOFs. In this respect, Fe-ICR-2, Al-ICR-2, and Fe-ICR-7 preserve the majority of their porosity. Clearly, both Fe-ICR-7 and Al-ICR-7 are more solvothermally stable than corresponding ICR-6 MOFs. This behaviour can be ra-tionalized by hydrophobicity of the phenyl groups point-ing into the pore accessible volume, effectively shielding the coordination bonds of the linkers.29,30

We also investigated the stability of ICR MOFs towards activation from water, i.e., under conditions when wet MOFs are dried on air without the exchange of water for other solvent before drying. Some water-stable Zr-MOFs, such as PCN-222 or NU-1000, loose porosity during the activation process from water.31 In contrast, phosphinate ICR MOFs, except for Al-ICR-6, display low variability in surface areas, indicating exceptional stability of the po-rous structure. The presented experimental results con-firm that the ICR family of MOFs represents robust mate-rials, well-suited for applications in aqueous environment.

Table 2. Specific surface areas of as-prepared and treated ICR MOFs.a

Sample As prepared

Reflux RT Activatedb

H2O EtOH Toluene H2O EtOH Toluene H2O

Fe-ICR-2 906 738 360 790 917 952 921 969

Fe-ICR-6 1134 172 1077 1081 1195 945 1174 1092

Fe-ICR-7 1125 896 1012 1061 1065 1122 1056 1077

Al-ICR-2 933 851 806 878 887 915 908 836

Al-ICR-6 1362 171 1444 1654 1087 1126 1212 747

Al-ICR-7 1030 701 1210 1076 1099 1164 1121 908

a Specific surface areas are in m

2 g

-1. The t-plot method was used for Fe-ICR-2 and Al-ICR-2, otherwise BET specific surface ar-

eas are given. b Activation from water.

Adsorption of bisphenol A. The robustness, pore size variability, and hydrophobic nature of the pores prompt-ed us to investigate the sorption properties of ICR MOFs towards hydrophobic pollutants. For these experiments, we selected Al-ICR MOFs as the porosity of Al-ICRs is greater than that of the Fe analogues and bisphenol A (BPA), a pollutant from the family of endocrine disruptors that represents significant threat in the food chain. The adsorption properties of Al-ICR MOFs were analyzed using high-performance liquid chromatography (HPLC). With the exception of Al-ICR-4 (PLD 2.9 Å), all other Al-ICR MOFs possess pores large enough to accommodate BPA molecules. The kinetic curves and adsorption iso-therms of Al-ICR MOFs were compared with those of conventional activated charcoal (abbreviated as AC, Sig-ma-Aldrich), measured under identical conditions. Prior to all measurements the adsorbents were activated under vacuum at 80 °C overnight.

The adsorption rate is an important factor for practical applications in environmental remediation. Figure 2 de-picts the recorded kinetic curves. The kinetic parameters, including the correlation factors obtained by non-linear fitting to the pseudo-second order kinetic model, are summarized in Table 3 and Table S3, and the correspond-ing fits are presented in Figure S62. Interestingly, the sorption equilibrium for AC, Al-ICR-2, and Al-ICR-7 was nearly completed within 15 min. In contrast, Al-ICR-6 behaved differently. The sorption kinetics indicates two consecutive processes, where a fast initial step is followed by a slow process, so that the equilibrium is not reached with the time frame of the sorption experiment (i.e., 360 min). This behaviour can be attributed to a slow rear-rangement of BPA molecules inside the pores indicated by molecular modelling. These results show that BPA can be arranged in two positions in the pores of Al-ICR-6 (for details see below).

0 60 120 180 240 300 360100

125

150

175

200

225

250

qe / m

g g

-1

Time / min

AC

Al-ICR-2

Al-ICR-6

Al-ICR-7

Figure 2. Kinetics of BPA adsorption by Al-ICR MOFs com-pared with that of AC. Conditions: initial BPA concentration 50 mg L

-1, 10 mg of the adsorbent dispersed in 50 mL BPA

solution, 25±1 °C. The experimental points are obtained from triplicate experiments (see Figure S62 for error bars).

Adsorption isotherms of BPA for Al-ICR MOFs and AC (Figure 3) were obtained using initial BPA concentrations from 10 to 120 mg L-1 after 24 h stirring at constant tem-perature (25±1 °C). The experimental data were fitted using the Langmuir, Freundlich, and Langmuir-Freundlich adsorption isotherm models (see the Support-ing Information for details). Best fits were obtained using the Langmuir model providing parameters summarized in Table 3. The results indicate that the sorption capacity for BPA increases in the order Al-ICR-4 < AC ≈ Al-ICR-2 < Al-ICR-7 < Al-ICR-6. The highest adsorption capacity (Qm) was found for Al-ICR-6 (326 mg g-1), which is approxi-mately by 50 % greater value than the Qm of AC (221 mg g-

1). On the other hand, the adsorption capacity of Al-ICR-2 is comparable to that of AC and Al-ICR-4 adsorbs very little at the external surface due to the narrow pores (PLD of 2.9 Å).

0 10 20 30 40 50 60 700

50

100

150

200

250

300

350

AC

Al-ICR-2

Al-ICR-4

Al-ICR-6

Al-ICR-7

qe / m

g g

-1

Ce / mg L

-1

Figure 3. Adsorption isotherms of BPA expressed as the dependence of the adsorbed amount of BPA (qe) on the BPA equilibrium concentration (Ce). The experimental points were obtained from triplicate experiments and the solid lines are the corresponding non-linear fits to the Langmuir ad-sorption model. For detail see the Supporting Information. Conditions: initial BPA concentration between 10 and 120 mg L

-1, 10 mg of the adsorbent dispersed in 50 mL BPA solu-

tion, 25±1 °C.

Table 3. Pseudo-second order kinetic constants and Langmuir isotherm constants obtained by non-linear fitting to the experimental data.a

Sample Kinetic constants Langmuir constants

qm

(mg g-1)

k2

(g mg-1

min-1)

Qm

(mg g-1)

KL

(L mg-1)

AC 183±2 0.022±0.001 221±4 0.81±0.04

Al-ICR-2 220±7 0.052±0.002 222±3 9.61±0.51

Al-ICR-4 n. a. n. a. 22±1 0.64±0.58

Al-ICR-6 194±4 0.010±0.002 326±8 0.15±0.01

Al-ICR-7 234±1 0.017±0.002 307±5 0.62±0.07

aAll data points were measured in triplicate experiments:

qm is the amount of BPA adsorbed at the equilibrium; k2 is the pseudo-second order kinetic rate constant; Qm is the Langmuir maximum sorption capacity; KL is the Langmuir constant.

Interestingly, the course of the adsorption isotherm of Al-ICR-2 is different from the isotherms of the other ad-sorbents. BPA was completely adsorbed from the disper-sions with initial concentrations up to 30 mg L-1, and Al-ICR-2 became fully saturated at the initial BPA concentra-tion of 50 mg L-1. On the other hand, Al-ICR-6, Al-ICR-7, and AC only partially removed BPA at low initial concen-trations; however, due to the high pore volumes, the Qm values are greater than that of Al-ICR-2. This observation correlates well with the values of KL constants of the Langmuir isotherms (Table 3), which are the measure of the adsorbent-adsorbate affinity. Thus, the high value for Al-ICR-2 (KL = 9.61) indicates high affinity of BPA towards Al-ICR-2. In contrast, the KL values for Al-ICR-6 and Al-ICR-7 are by more than one order of magnitude lower

(0.15 and 0.62, respectively), indicating that the affinity of BPA to ICR MOFs with larger pores is significantly lower when compared with that of Al-ICR-2.

The stability of MOFs in aqueous media is an important issue affecting their applicability. For this reason, we also characterized Al-ICR MOFs by PXRD and N2 adsorption isotherms after the sorption of BPA and regeneration done by washing with water and acetone (Figure S64 and Table S4). These characteristics are in line with the results presented above on the treatment Al-ICR MOFs with water at RT, confirming that Al-ICR MOFs are stable during the sorption experiments. In addition, the adsorp-tion process is reversible, i.e., BPA can be washed out from the pores of Al-ICR MOFs with acetone (see the Supporting Information for details).

Summing up, Al-ICR MOFs are endowed with greater adsorption capacity than zeolites, graphene, imprinted polymers, montmorillonite, and other materials.5 In re-cent years, several MOFs were successfully tested as ad-sorbents of BPA. The Qm values for typical carboxylate-based MOFs (such as Fe-MIL-100, Cr-MIL-101) do not exceed 260 mg g-1.32 Only Al-MIL-53 displays a similar maximum sorption capacity (325 mg g-1) to Al-ICR-6.33

Molecular modelling. We used molecular modelling in order to analyze the interactions of BPA inside the MOF pores. As described above, the pores are of hexago-nal shape with the phenyl or methyl substituents bonded to P atoms aiming at the centre of the pore. These sub-stituents along with the pore diameter can influence the interactions and arrangement of guest molecules as well as the sorption capacity.

The interaction energies between BPA and Al-ICR MOFs for relevant BPA amounts adsorbed in the pores are summarized in Table 4. At low concentrations of BPA in the framework (one BPA molecule per pore in the supercell, i.e., qe ≈ 10 mg g-1), the interaction energies decrease in the order Al-ICR2 > Al-ICR-6 > Al-ICR-7. The snapshots of BPA arrangements are given in Figure 4a-c. The interaction energies in the Al-ICR-2 pores are nearly flat up to the loading of approximately 200 mg g-1. This behaviour is in good agreement with the observed high affinity of BPA towards Al-ICR-2, indicated by nearly quantitative adsorption of BPA at these concentrations and high KL value.

Interestingly, there are two positions of BPA in the Al-ICR-6 pore (Figure S65) with an interaction energy differ-ence of 2.9 kcal mol-1 (details in the Supporting Infor-mation). The existence of two binding sites and the relo-cation of BPA molecule between these two sites during simulation can be the reasons of the measured slow ad-sorption kinetics (Figure 2). At higher BPA concentrations (up to qe ≈ 300 mg g-1), the interaction energy decreases due to BPA-BPA stacking interactions making the system quite disordered (Figure 4d and Figure S66). The average interaction energies for Al-ICR-6 and Al-ICR-7 decrease with the increasing loading of BPA in agreement with the low KL values found for these materials (Table 3).

Figure 4. BPA molecule in the 1D pores of Al-ICR-2 (a), ICR-6 (b), and ICR-7(c), view along the c axes, qe ≈ 10 mg g

-1.

Arrangement of BPA molecules in the 1D pore of Al-ICR-6, qe ≈ 30 mg g

-1 view perpendicularly to the c axis (d).

Table 4. Interaction energies between BPA and Al-ICR MOFs per one BPA molecule.a

Sample

qe (mg g-1)

10 100 200 300

Al-ICR-2 -22.2±0.4 -21.3±0.3 -21.2±0.3 n.a.

Al-ICR-6

-20.3±0.4b -17.7± 0.2 -17.6±0.2 -16.4±0.2

Al-ICR-7 -18.2±0.4 -16.3 ±0.3 -16.3±0.2 -15.3±0.5

a qe is the adsorbed amount of BPA per gram of Al-ICR

MOF, interaction energies are given in kcal mol-1.

b The in-

teraction energy is the weighted average over two BPA posi-tions shown in Figure. S65.

CONCLUSIONS

We synthesized new ICR-6 and ICR-7 MOFs isoreticu-lar with Fe-ICR-2 and Fe-ICR-4 described earlier.20 We also shown that Al3+ cations can be successfully used for the construction of ICR MOFs. ICR MOFs have high thermal and solvothermal stability. Due to the hydropho-bic character of the ICR pore walls, ICR MOFs effectively adsorb BPA with greater sorption capacities than the majority of already investigated adsorbents.

Summing up, this work extends the area of phosphinic acid-based MOFs. The isoreticular design is applicable and the wide variety of water-stable MOFs can be pre-pared using various substituents at phosphorus atom. We envision that the number of phosphinic acid-based MOFs will steeply increase in coming years.34

EXPERIMENTAL SECTION

Preparation of Fe-ICR-2, Fe-ICR-4, Fe-ICR-7, and Al-ICR MOFs

A teflon lined autoclave (Berghof DAB-2) was charged with 0.08 mmol linker and 0.04 mmol of FeCl3·6H2O (10.8 mg) or AlCl3·6H2O (9.7 mg), and overlaid with 5 mL of

absolute EtOH. The sealed autoclave was heated in a preheated heating mantle (Berghof BTC-3000) at 250 °C for 24 h. The resulting white powder was centrifuged (11,000 rpm, 5 min, Hettich, Rotina 380 R), washed five times with EtOH (third time it was left in EtOH for two hours), three times with water (second time it was left in water overnight), twice with acetone (third time it was left in acetone for one and half hours), and activated at 80 °C for five hours under vacuum.

Preparation of Fe-ICR-5

A teflon lined autoclave (Berghof DAB-2) was charged with 0.08 mmol of H2BBP(Me) and 0.04 mmol FeCl3·6H2O (10.8 mg), and overlaid with 5 mL of absolute EtOH. The sealed autoclave was heated in a preheated heating man-tle (Berghof BTC-3000) at 250 °C for 24 h. The resulting white powder was centrifuged (11,000 rpm, 5 min, Het-tich, Rotina 380 R), washed five times with acetone, and dried on air.

Preparation of Fe-ICR-6

A Wheaton vial was charged with 37.2 mg H2BBP(Me) (0.12 mmol) and overlaid with 25 mL of dimethylforma-mide (DMF). After 10 min sonication, 16.2 mg of FeCl3·6H2O (0.06 mmmol) in 5 ml of DMF was added. The vial was heated in a preheated oven (Berghof BTC-3000) at 120 °C for 72 h. The resulting white powder was centri-fuged (11,000 rpm, 5 min, Hettich, Rotina 380 R) and washed as described for Fe-ICR-2.

Stability of ICR MOFs

20 mg of MOF was suspended in 10 mL of H2O, EtOH, or toluene and the suspension was shaken for 24 h at RT or refluxed for 24 h. After that, the solid material was collected by centrifugation, washed twice with water (only in the case of stability tests in water) or EtOH (in the case of stability tests in EtOH and toluene), and twice with acetone. The resulting powders were air-dried at RT.

Adsorption of BPA

The adsorption experiments were performed in sealed 100 mL reagent SIMAX glass bottles in a temperature-controlled room with constant temperature of 25±1 °C and BPA concentrations between 10 and 120 mg L-1. The bot-tles were charged with 10 mg of Al-ICR MOF or activated

charcoal (AC, DARCO®, 100 mesh particle size, powder, Sigma Aldrich) and 10 mL of water followed by 5 min sonication. Then, 40 mL of BPA solution was added. The mixture was stirred for 24 h at 25 °C and then 1 mL of sample was taken, filtered through a PTFE microfilter (0.2 µm, Whatman), and the remaining concentration of BPA was analysed using HPLC-DAD.

ASSOCIATED CONTENT

Supporting Information. Detailed experimental proce-dures, FTIR, PXRD, Rietveld fits, TGA, and details for adsorp-tion of BPA and molecular modelling (PDF). This material is available free of charge via the Internet at http://pubs.acs.org.

AUTHOR INFORMATION

Corresponding Author

* E-mail: [email protected]

ORCID

Daniel Bůžek: 0000-0002-7387-9461 Jan Hynek: 0000-0003-1883-9464 Kamil Lang: 0000-0002-4151-8805 Jan Rohlíček: 0000-0001-6913-2667 Jan Demel: 0000-0001-7796-6338

Notes The authors declare no competing financial interest.

ACKNOWLEDGMENT

This work was supported by the Czech Science Foundation (No. 20-04408S) and partial project DPK/2018/14 from the Technology Agency of the Czech Republic (GAMA COMNID TG02010049). X-ray diffractometers were supported by the Operational Programme Research, Development and Educa-tion financed by the European Structural and Investment Funds and the Ministry of Education, Youth and Sports (No. SOLID21 CZ.02.1.01/0.0/0.0/16_019/0000760). The computa-tional study was supported by the CESNET LM2015042 and the CERIT Scientific Cloud LM2015085, provided under the programme "Projects of Large Research, Development, and Innovations Infrastructures". The authors acknowledge the assistance provided by the Research Infrastructure NanoEn-viCz, supported by the Ministry of Education, Youth and Sports of the Czech Republic under Project No. LM2015073.

ABBREVIATIONS

ICR Inorganic Chemistry Řež; MOF Metal-organic frame-work; SBU Secondary building unit; DMF N,N-dimethylformamide; PXRD Powder X-ray diffraction; PLD Pore limiting diameter; BET Brunauer-Emmett-Teller; NLDFT Non-local density functional theory; AC Activated charcoal; BPA Bisphenol A; HPLC High-performance liquid chromatography.

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Bisphenol A adsorption

Isoreticular design of phosphinic acid-based ICR MOFs

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1

Supporting Information

Robust Aluminium and Iron Phosphinate Metal Organic Frameworks for Efficient

Removal of Bisphenol A

Daniel Bůžek,a,b

Soňa Ondrušová,a Jan Hynek,

a Petr Kovář,

c Kamil Lang,

a Jan Rohlíček,

d Jan

Demela*

a Institute of Inorganic Chemistry of the Czech Academy of Sciences, 250 68 Řež, Czech

Republic; E-mail: [email protected]

b Faculty of the Environment, Jan Evangelista Purkyně University, Králova Výšina 3132/7,

400 96 Ústí nad Labem, Czech Republic

c Charles University, Faculty of Mathematics and Physics, Ke Karlovu 3, 121 16,

Praha 2, Czech Republic

d Institute of Physics of the Czech Academy of Sciences, 182 21 Praha, Czech Republic

2

Table of content

Experimental procedures

Table S1 Elemental analysis of ICR MOFs.

Figures S1-S7 FTIR spectra of ICR MOFs.

Figures S8-S14 TGA/DTA curves and the evolution of gases for ICR MOFs.

Table S2 Crystallographic data.

Figures S15-S18 Rietveld fits of Fe-ICR-5, Fe-ICR-6, Fe-ICR-7, and Al-ICR-4.

Figure S19 Comparison of crystal structure of Fe-ICR-3 and Fe-ICR-5.

Figure S20 Comparison of PXRD patterns of Al- and Fe-ICR MOFs.

Figures S21-24 Pore size distributions of all ICR MOFs.

Figures S25-S42 PXRD of ICR MOFs after treatment in H2O, EtOH, toluene, and

activation from water.

Figure S43 Nitrogen adsorption isotherms of as-prepared Al-ICR-2, Al-ICR-4, Al-

ICR-6, and Al-ICR-7.

Figures S44-S61 Nitrogen adsorption isotherms of ICR MOFs after treatment in H2O,

EtOH, toluene, and activation from water.

Equations used for the analysis of adsorption properties of ICR MOFs.

Figure S62 Kinetic curves of BPA adsorption.

Figure S63 Non-linear fitting of BPA adsorption isotherms.

Table S3 Langmuir, Freundlich, and Langmuir-Freundlich parameters.

Figure S64 PXRD patterns of Al-ICR MOFs before and after adsorption of BPA.

Table S4 BET surface area of Al-ICR MOFs before and after adsorption of BPA.

Details of molecular modelling.

Figure S65 Arrangement of BPA inside the Al-ICR-6 pores.

Figure S66 Arrangement of BPA molecules with a loading of 300 mg g-1

in the

pores of Al-ICR-6 and Al-ICR-7.

3

Experimental Procedures

Materials. MePCl2 (Acros Organics), AlCl3·6H2O, N,N-dimethylformamide (DMF) (both

Penta, Czech Republic), benzene (anhydrous), PhPCl2, 1,4-dibromobenzene, 4,4′-

dibromobiphenyl, activated charcoal (AC), Pd(PPh3)4, FeCl3·6H2O (all Sigma-Aldrich),

ethanol (absolute, Fischer Chemical), were used as purchased. 1,4-dioxane (water-free, VWR

Chemicals), dichloromethane (HPLC grade, Fisher Scientific), and methanol (anhydrous,

VWR Chemicals) were dried using a solvent purifier SP-1 (LC Technology Solutions).

Triethylamine (Sigma-Aldrich) was freshly distilled from Na under Ar. Acetonitrile (Lach-

Ner, Czech Republic) was dried using molecular sieves (3 Å, Sigma Aldrich). The synthesis

of linkers was performed under Ar using standard Schlenk technique. Column

chromatography was performed on Sigma-Aldrich 60 (70-230 mesh, 60 Å) silica gel.

Preparation of linker molecules

General procedure for preparation of methyl R-phosphinates. A Schlenk tube was

charged with RPCl2, three times evacuated and flushed with Ar, and diluted with dry benzene

(8 mL per 1 g of RPCl2). In a second Schlenk tube, 2.4 molar equivalents of dry MeOH were

mixed with 1 molar equivalent of dry triethylamine under Ar atmosphere. The mixture was

cooled by an ice bath and the solution of RPCl2 was slowly added. The formed precipitate was

filtered off and the filtrate was evaporated yielding an oily product which was directly used

without any purification for further synthesis.

Methyl methylphospinate.

Yield: 5.17 g (64 %).

1H NMR (CDCl3): δ 1.55 (d,

2JPH = 15.6 Hz, 3H); 3.78 (d,

3JPH = 12.0 Hz, 3H); 7.19 (d,

1JPH =

540 Hz, 1H). 31

P{1H} NMR (CDCl3): δ 37.51.

Methyl phenylphospinate.

Yield: 10.7 g (80 %).

1H NMR (CDCl3): δ 3.78 (d,

3JPH = 12.3 Hz, 3H); 7.49 – 7.53 (m, 2H); 7.55 (d,

1JPH = 566

Hz, 1H); 7.58 – 7.62 (m, 1H); 7.75 – 7.80 (m, 2H). 31

P{1H} NMR (CDCl3): δ 27.75.

General procedure for preparation of dimethyl arylene bis(R-phosphinates). A flask was

charged with dibromoarene and 0.16 molar equivalents of Pd(PPh3)4, three times evacuated

and flushed with Ar, and sealed with a septum. Then, 2.4 molar equivalents of dry

4

triethylamine and 3 molar equivalents of methyl or phenyl phosphinate were dissolved in dry

1,4-dioxane under Ar atmosphere, and added to the dibromoarene mixture. The resulting

yellow solution was stirred at 60 °C for 96 h. After cooling down, the formed precipitate was

filtered off and the filtrate was evaporated to dryness. The solid residue was dissolved in

dichloromethane and washed three times with water. The purification process was individual

for each product, see below.

Dimethyl phenylene-1,4-bis(methylphosphinate). The mixed water fractions were

evaporated to dryness. The obtained mixture of the desired product with residual

triethylamine hydrobromide was used for the following synthetic step without any further

purification. Yield 5.12 g (82 %).

1H NMR (CDCl3): δ 1.55 (d,

2JPH = 14.4 Hz, 6H); 3.64 (d,

3JPH = 11.2 Hz, 6H); 7.87 – 7.97

(m, 4H). 31

P{1H} NMR (CDCl3): δ 43.4.

Dimethyl phenylene-1,4-bis(phenylphosphinate). The organic phase was dried over

MgSO4. The solution was evaporated and the product was precipitated by addition of diethyl

ether, filtered off, and washed until the filtrate was colourless. Yield: 5.6 g (61 %).

1H NMR (CDCl3): δ 3.75 (d,

3JPH = 11.4 Hz, 6H); 7.43 – 7.47 (m, 4H); 7.51 – 7.54 (m, 2H);

7.78 (dd, 3JPH = 12.0 Hz,

3JHH = 7.8 Hz, 4H); 7.87 (dd,

3JPH = 9.0 Hz,

3JHH = 6.0 Hz, 4H).

31P{

1H} NMR (CDCl3): δ 32.4.

Dimethyl biphenylene-4,4’-bis(methylphosphinate). The organic phase was dried over

MgSO4. The solution was evaporated and the product was precipitated by the addition of

diethyl ether, filtered off, and washed with diethyl ether and DMF until the filtrate was

colourless. Yield: 7.6 g (70 %).

1H NMR (CDCl3): δ 1.55 (d,

2JPH = 14.4 Hz, 6H); 3.75 (d,

3JPH = 11.6 Hz, 6H); 7.73 (dd,

3JPH

= 14.8 Hz, 3JHH = 7.8 Hz, 4H); 7.84 (dd,

4JPH = 10.2 Hz

3JHH = 7.8 Hz, 4H).

31P{

1H} NMR

(CDCl3): δ 44.3.

Dimethyl biphenylene-4,4’-bis(phenylphosphinate). The organic phase was dried over

MgSO4. The solution was evaporated and the product was precipitated by the addition of

acetonitrile, filtered off, and washed until the filtrate was colourless. Yield: 3.52 g (54 %).

1H NMR (CDCl3): δ 3.79 (d,

3JPH = 10.8 Hz, 6H); 7.47 (td,

3JHH = 7.8 Hz,

4JPH = 3.6 Hz, 4H);

7.54 (t, 3JHH = 7.8 Hz, 2H); 7.65 (dd,

3JHH = 7.8 Hz,

4JPH = 3.0 Hz, 4H); 7.83 (dd,

3JPH = 12.6

5

Hz, 3JHH = 7.8 Hz, 4H); 7.88 (dd,

3JPH = 12.0 Hz,

3JHH = 7.8 Hz, 4H).

31P{

1H} NMR (CDCl3):

δ 33.5.

General procedure for preparation of arylene bis(R-phosphinic acids). A Schlenk tube

was charged with dimethyl arylene bis(R-phosphinate), evacuated and flushed with argon

three times, and then acetonitrile (approx. 40 mL g-1

) was added followed by a dropwise

addition of 3 molar equivalents of trimethylsilyl bromide. In the case of dimethyl

biphenylene-4,4’-bis(phenylphosphinate), dichloromethane was used instead of acetonitrile

due to poor solubility of the ester in acetonitrile. The resulting mixture was stirred at 40 °C for

16 h. The purification process was individual for each product, see below.

Phenylene-1,4-bis(methylphosphinic acid) (H2PBP(Me)). After cooling down the solution

was evaporated to dryness. The solid residue was dissolved in water and the water solution

was washed with diethyl ether three times. The water fraction was evaporated and the crude

product was purified by trituration with acetone. Yield: 10.1 g (66 %).

1H NMR (CD3OD): δ 1.69 (d,

2JPH = 14.4 Hz, 6H); 7.93 – 8.03 (m, 4H).

31P{

1H} NMR

(CD3OD): δ 39.3. 13

C{1H} NMR (CD3OD): δ 15.1 (d,

1JPC = 101 Hz); 130.6 (t, JPC = 12 Hz);

137.7 (d, 1JPC = 129 Hz).

Phenylene-1,4-bis(phenylphosphinic acid) (H2PBP(Ph)). After cooling down, the solution

was precipitated by addition of water. The solid product was filtered off and washed with

acetonitrile, water, and acetone. Yield: 5.0 g (96 %).

1H NMR ((CD3)2SO): δ 7.43 (dt,

3JHH = 7.2 Hz,

4JPH = 3.0 Hz, 4H); 7.50 (t,

3JPH = 7.2 Hz,

2H); 7.68 (dd, 3JPH = 12.0 Hz,

3JHH = 7.2 Hz, 4H); 7.77 (dd,

3JPH = 8.4 Hz,

3JHH = 6.0 Hz, 4H).

31P{

1H} NMR (CD3OD): δ 23.1.

13C{

1H} NMR (CD3OD): δ 129.1 (d, JPC = 13 Hz); 131.4 (t,

JPC = 12 Hz); 131.5 (d, JPC = 11 Hz); 132.2 (s); 134.9 (d, 1JPC = 135 Hz); 138.7 (d,

1JPC = 130

Hz).

Biphenylene-4,4’-bis(methylphosphinic acid) (H2BBP(Me)). After cooling down, the

reaction mixture was evaporated to dryness. The solid residue was suspended in ethanol. The

product was filtered off and washed with acetone and diethyl ether. Yield: 6.9 g (99 %).

1H NMR ((CD3)2SO): δ 1.51 (d,

2JPH = 15.0 Hz, 6H); 7.75 – 7.80 (m, 8H).

31P{

1H} NMR

((CD3)2SO): δ 34.8. 13

C{1H} NMR ((CD3)2SO): δ 17.4 (d,

1JPC = 111 Hz); 127.4 (d, JPC = 12

Hz); 131.7 (d, JPC = 9 Hz); 135.6 (d, 1JPC = 127 Hz); 142.6 (s).

6

Biphenylene-4,4’-bis(phenylphosphinic acid) (H2BBP(Ph)). After cooling down, the

solution was evaporated and the residue was precipitated by the addition of water. The solid

product was filtered off and washed with water, acetone, and diethyl ether. Yield: 3.2 g (96

%).

1H NMR ((CD3)2SO): δ 7.44 (td,

3JHH = 7.2 Hz,

4JPH = 3.0 Hz, 4H); 7.54 (t,

3JHH = 6.6 Hz,

2H); 7.70 – 7.79 (m, 12H). 31

P{1H} NMR (CD3OD): δ 23.7.

13C{

1H} NMR ((CD3)2SO): δ

127.6 (d, JPC = 12 Hz); 129.0 (d, JPC = 12 Hz); 131.5 (s); 132.1 (d; JPC = 9 Hz); 135.0 (d, 1JPC

= 135 Hz); 135.4 (d, 1JPC = 135 Hz); 142.5 (s).

Preparation of ICR MOFs

Preparation of Fe-ICR-2, Fe-ICR-4, and Fe-ICR-7. A teflon lined autoclave (Berghof

DAB-2) was charged with 0.08 mmol linker and 0.04 mmol FeCl3·6H2O (10.8 mg) and

overlaid with 5 mL of absolute EtOH. The sealed autoclave was heated in a preheated heating

mantle (Berghof BTC-3000) at 250 °C for 24 h. The resulting white powder was centrifuged

(11,000 rpm, 5 min, Hettich, Rotina 380 R), washed five times with EtOH (third time it was

left in EtOH for two hours), three times with water (second time it was left in water

overnight), three times with acetone (third time it was left in acetone for 1.5 h), and activated

at 80 °C for five hours under dynamic vacuum.

Preparation of Fe-ICR-5. A teflon lined autoclave (Berghof DAB-2) was charged with 0.08

mmol of H2BBP(Me), 0.04 mmol FeCl3·6H2O (10.8 mg), and overlaid with 5 mL of absolute

EtOH. The sealed autoclave was heated in a preheated heating mantle (Berghof BTC-3000) at

250 °C for 24 h. The resulting white powder was centrifuged (11,000 rpm, 5 min, Hettich,

Rotina 380 R), washed five times with acetone, and dried on air.

Preparation of Fe-ICR-6. A Wheaton vial was charged with 37.2 mg H2BBP(Me) (0.12

mmol) with 25 ml of DMF. After 10 min sonication 0.06 mmol of FeCl3·6H2O (16.2 mg) in 5

mL of DMF was added. The vial was heated in a preheated oven (Berghof BTC-3000) at 120

°C for 72 h. The resulting white powder was centrifuged (11,000 rpm, 5 min, Hettich, Rotina

380 R) and washed as described above for Fe-ICR-2.

Preparation of Al-ICR-2, Al-ICR-4, Al-ICR-6, and Al-ICR-7. A teflon lined autoclave

(Berghof DAB-2) was charged with 0.0425 mmol linker and 0.0213 mmol AlCl3·6H2O (5.13

mg) and overlaid with 10 mL of absolute EtOH. The sealed autoclave was heated in a

7

preheated heating mantle (Berghof BTC-3000) at 250 °C for 24 h. The resulting white powder

was centrifuged (11,000 rpm, 5 min, Hettich, Rotina 380 R) and washed as described above

for Fe-ICR-2.

Stability studies

20 mg of ICR MOF was suspended in 10 mL of water, EtOH, or toluene and the suspension

was shaken at RT or refluxed for 24 h. After that, the solid material was collected by

centrifugation, washed twice with water (in the case of stability tests in water) or ethanol (in

the case of stability tests in ethanol or toluene), and twice with acetone. The resulting powders

were air-dried at RT.

Activation from wet suspension was done by suspending 20 mg of ICR MOF in water and

letting the water freely evaporate on air at RT.

Sorption of bisphenol A (BPA)

The sorption of BPA was performed in sealed 100 mL SIMAX glass bottles with initial

concentrations ranging from 10 to 120 mg L-1

in a temperature-controlled room with constant

temperature of 25 ± 1 °C. The bottles were charged with 10 mg of Al-ICR MOF or activated

charcoal (AC, DARCO®, 100 mesh particle size, powder, Sigma Aldrich) and 10 mL of water,

followed by 5 min sonication. Then, 40 mL of BPA solution of the required concentration was

added. The mixture was stirred for 24 h at 25 °C and then 1 mL of sample was taken, filtered

through a PTFE microfilter (0.2 µm, Whatman), and the equilibrium concentration of BPA

was determined using an HPLC-DAD instrument. A set of experiments using different

sorption times showed that 24 h ensures the establishing of the equilibrium.

The kinetic experiments were performed using a similar procedure. The initial concentration

of BPA was set to 50 mg L-1

, 0.3 mL aliquots were taken at predefined times (1 - 360 min)

and analysed. All experiments were performed under stirring in the temperature-controlled

room at 25 ± 1 °C.

8

All sorption experiments were performed in water of natural pH without any pH adjustment.

The natural pH in all cases was 4.5 ± 0.3. All presented results are average of three

independent experiments giving the relative standard deviation lower than 7 %.

The Al-ICR MOFs were regenerated after the sorption of BPA by washing three times with

water and three times with acetone. These solid samples were then analysed by PXRD and N2

adsorption isotherms.

The kinetic and adsorption curves were analysed using a pseudo-second order model and

Langmuir, Freundlich, and Langmuir-Freundlich adsorption isotherms (corresponding

equations are given below), respectively. The equilibrium points were not used for fitting to

the pseudo-second order kinetic model (approximately > 100 min) as recommended in

literature.1

Instrumental methods

NMR spectra were measured on a JEOL 600 MHz NMR spectrometer. 1H and

13C NMR

spectra were referenced on the residual signal of the solvent. CHN elemental analysis was

performed using a standard combustion technique (Thermo Scientific FlashSmartTM 2000

Elemental analyzer). Powder X-ray diffractions (PXRD) were recorded using an Empyrean

diffractometer (PANalytical), which was equipped by a capillary holder, focusing mirror and

PIXcel3D detector. The PXRD pattern of Fe-ICR-5 was collected using a SmartLab

diffractometer of Rigaku equipped with a Cu rotating anode, primary monochromator,

capillary holder, and D/tex 250 detector.

The structure of Fe-ICR-5 and Fe-ICR-7 was determined by the Rietveld refinement using the

Jana2006 software.2 The procedure was identical for both crystal structures. In order to keep a

reasonable geometry of the molecular model, bond length and bond angle restraints were

introduced and one isotropic atomic displacement parameter (ADP) parameter was shared by

C, O, and P atoms and one ADP was shared by Fe atoms. Hydrogen atoms were kept in their

theoretical positions. At the final stage of the Rietveld refinement, the coordinates of C, O, P,

and Fe atoms were refined using restraints discussed above together with their shared ADPs,

unit cell parameters, background, and scale factor. The results and the final profile fit are

shown in Table S2 and Figures S15-S16.

9

The structure of Al-ICR-4 was solved by the Rietveld refinement in the Jana2006 software.

The Fe-ICR-4 structure was taken as an initial crystal structure where all Fe atoms were

replaced by Al atoms. At the final stage of the refinement, the rigid body approach was

introduced for two phenyl rings (atoms C7-C12), where only position and rotation of the

phenyl fragment was refined. The third phenyl ring occupies a special position and for that

reason the atomic positions of C atoms in this phenyl ring were refined using bond and bond

angle restraints as well as oxygen atoms connecting to phosphorus atoms. Hydrogen atoms

were kept in their theoretical positions. Carbon and oxygen atoms shared one isotropic ADP,

while phosphorus atoms had their own, and ADP of the aluminium atom was refined as

harmonic. The final Rietveld refinement led to low agreement factors Rwp = 0.0298, Rp =

0.0349, GOF = 2.9 (Table S2). The final plot of the fit is in Figure S17.

Adsorption isotherms of N2 were recorded using a Belsorp maxII instrument. Prior to

adsorption experiments, the samples were evacuated at 80 °C for at least 24 h. Due to the

microporous nature of Fe-ICR-2, Al-ICR-2, Fe-ICR-4, and Al-ICR-4, the determination of

BET surface area did not provide reliable data (negative C value within the range P/P0 = 0.05-

0.3). Therefore, the surface areas of these ICRs were determined from the t-plot. The pore size

distribution was calculated from the adsorption branch either using the NLDFT method for

cylindrical pores (Fe-ICR-6, Al-ICR-6, Fe-ICR-7, Al-ICR-6) as provided by the Belsorp

software or by the MP plot (Fe-ICR-2, Al-ICR-2, Fe-ICR-4, Al-ICR-4).

Thermal analyses (TG/DTA/MS) were carried out on a Setaram SETSYS Evolution-16-MS

instrument coupled with a mass-spectrometer. The measurements were performed in synthetic

air (flow rate 30 mL min−1

) from 30 to 750 °C with a heating rate of 5 °C min−1

. Fourier

transform infrared spectra (FTIR) were collected on a Nicolet NEXUS 670-FT spectrometer

in KBr pellets (2000−400 cm−1

).

An HPLC-DAD DIONEX UltiMate 3000 instrument was used for the concentration analysis

of BPA in sorption experiments. The HPLC system was equipped with a diode array detector,

20 µL sampling loop, and Kinetex 2.6 µm C18 column (Phenomenex, USA, 50 mm x 3 mm).

Methanol/water mixture was used as a mobile phase (0.5 mL min-1

, both solvents contained

0.1 % HCOOH) under isocratic elution ratio of 55/45 (v/v). The time of analysis was set to 3

min. The signals were collected at 215 nm. The concentrations of BPA were determined using

the standard calibration curve method.

10

Table S1. Elemental analysis of ICR MOFs.

Sample C: Wcalcd C: Wfound H: Wcalcd H: Wfound

Fe-ICR-2 35.67 35.74 3.74 3.73

Fe-ICR-4 54.94 52.97 3.59 3.62

Fe-ICR-6 48.68 48.57 4.08 4.18

Fe-ICR-7 61.38 60.94 3.86 3.74

Al-ICR-2 38.42 37.59 4.03 4.09

Al-ICR-4 57.77 55.15 3.77 3.80

Al-ICR-6 51.55 49.43 4.33 4.33

Al-ICR-7 64.01 62.62 4.03 4.05

FTIR spectrum of Fe-ICR-2 is presented in the previous publication.3

4000 3500 3000 2500 2000 1500 1000 500

0

10

20

30

40

50

60

70

80

90

100

1486

459

520

748

1438

3065

835

1629

1053

694

715

1379

5921017

3432

1135

1594

822

561

Tra

nsm

itta

nce/%

Wavenumber/cm-1

3030

Figure S1. FTIR spectrum of Fe-ICR-4.

11

4000 3500 3000 2500 2000 1500 1000 500

0

10

20

30

40

50

60

70

80

90

100

1411

3026

3057

529

491

1600

2985

880

1632

1000

815

770

569

1542

1050

3422

1386

1136

1296

694

1484

Tra

nsm

itta

nce/%

Wavenumber/cm-1

2919


4000 3500 3000 2500 2000 1500 1000 500

0

10

20

30

40

50

60

70

80

90

100

451

1630

3027

588

1483

3052

1601

1061

749

723

815

694

1135

3423

1436

1542

1387

999

547

Tra

nsm

itta

nce/%

Wavenumber/cm-1


12

4000 3500 3000 2500 2000 1500 1000 500-10

0

10

20

30

40

50

60

70

80

90

476

1020

1297

2986

879

1634

1095

732

770

826

549

1151

3424

1415

1196

1381

961

518

Tra

nsm

itta

nce/%

Wavenumber/cm-1

2922

Figure S4. FTIR spectrum of Al-ICR-2.

4000 3500 3000 2500 2000 1500 1000 500-10

0

10

20

30

40

50

60

70

80

961

824

751

1637

1076

694

597

717

470

1146

3449

1438

1177

1382

1023

526

Tra

nsm

itta

nce/%

Wavenumber/cm-1

3071


13

4000 3500 3000 2500 2000 1500 1000 500-10

0

10

20

30

40

50

60

70

80

90

815

1484

1602

3059

1003

1300

2986

883

1634

1072

570

775

696

528

1140

3420

1541

1387

962

495

Tra

nsm

itta

nce/%

Wavenumber/cm-1

2921


4000 3500 3000 2500 2000 1500 1000 500-10

0

10

20

30

40

50

60

70

80

90

459

1635

819

1487

3054

1071

1438

953

1600

1132

696

724

750

595

1189

3429

1541

1386

1004

550

Tra

nsm

itta

nce/%

Wavenumber/cm-1

3028


14

TGA/DTA curves and the evolution of gases for Fe-ICR-2 in air are published in the previous

publication.3

100 200 300 400 500 600

-50

-40

-30

-20

-10

0

-0.5

-0.4

-0.3

-0.2

-0.1

0.0

-20

0

20

40

60

80

100

0.0

0.1

0.2

0.3

0.4

0.5

0.0

0.1

0.2

100 200 300 400 500 600

100 200 300 400 500 600

-46.5%(378°- 650°C)

-1%(30°- 378°C)

<+

>

<+

>

TG

m

/%

Temperature / °C

504°C

-->

exo

DTA / µVDTG / (mg*min-1

)

505°C

0.0

0.1

0.2

0.3

0.4

0.5

17+

505°C

505°C

504°C

Intensity of m=44/ A*E-6

18+

44+

Intensity of m=58,98/A*E-9

Inte

nsity o

f m

=1

7,1

8/A

*E-6

0.0

0.1

0.2

507°C

506°C

98+

58+

43+

Inte

nsity o

f m

=4

3/A

*E-8

Figure S8. TGA/DTA curves and the evolution of gases for Fe-ICR-4 in air; m/z = 17 – OH,

m/z = 18 –H2O, m/z = 44 – CO2, m/z = 43 and 58 – acetone, and m/z = 98 – H3PO4.

15

100 200 300 400 500 600

-50

-40

-30

-20

-10

0

-0.4

-0.3

-0.2

-0.1

0.0

-20

0

20

40

60

80

100

0.0

0.1

0.2

0.0

0.1

0.2

0.3

100 200 300 400 500 600

100 200 300 400 500 600

<+

>

-13.4%(367°- 476°C)

-28.8%(476°- 650°C)

-1.8%(30°- 367°C)

<+

>

<+

>

TG

m

/%

Temperature / °C

517°C

463°C

-->

exo


)

82°C

484°C

463°C

0.0

0.1

0.2458°C

463°C

17+

463°C

92°C

502°C


18+

44+


Inte

nsity o

f m

=1

7,1

8/A

*E-6

0.0

0.1

0.2

0.3

0.4

114°C

463°C 98

+58

+

43+

Inte

nsity o

f m

=4

3/A

*E-8

114°C



16

100 200 300 400 500 600

-60

-50

-40

-30

-20

-10

0

-0.8

-0.7

-0.6

-0.5

-0.4

-0.3

-0.2

-0.1

0.0

-20

0

20

40

60

80

100

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.0

0.1

0.2

100 200 300 400 500 600

100 200 300 400 500 600

-20.5%(520°- 650°C)

<+

>

-36.5%(422°- 520°C)

-1.2%(30°- 422°C)

<+

>

<+

>

TG

m

/%

Temperature / °C

525°C

514°C

-->

exo


)

525°C5

05°C 5

16°C

0.0

0.1

0.2

0.3

0.4

0.5

0.6

525°C

514°C

17+

514°C

514°C


18+

44+


Inte

nsity o

f m

=1

7,1

8/A

*E-6

0.0

0.1

0.2

514°C

514°C

514°C

98+

58+

43+

Inte

nsity o

f m

=4

3/A

*E-8



17

100 200 300 400 500 600 700

-40

-35

-30

-25

-20

-15

-10

-5

0

-1.0

-0.9

-0.8

-0.7

-0.6

-0.5

-0.4

-0.3

-0.2

-0.1

0.0

-30

-20

-10

0

10

20

30

40

50

60

70

80

0.0

0.2

0.4

0.6

0.8

1.0

0.0

0.4

0.8

1.2

1.6

2.0

2.4

2.8

3.2

100 200 300 400 500 600 700

100 200 300 400 500 600 700

547°C

85°C 558°C

-31.2%(286°- 750°C)

98°C

-2.9%(30°- 286°C)

<+

>

<+

>

TG

m

/%

Temperature / °C

-->

exo


)

0.0

0.2

0.4

0.6

0.8

1.0

492°C

89°C

Intensity of m=98/A*E-10

502°C

502°C

17+

557°C

89°C

557°C

558°C


18+

44+


Inte

nsity o

f m

=1

7,1

8/A

*E-6

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

552°C

501°C

114°C

547°C

114°C

98+

58+

43+

Inte

nsity o

f m

=4

3/A

*E-8

0.0

0.4

0.8

1.2

1.6

2.0

Figure S11. TGA/DTA curves and the evolution of gases for Al-ICR-2 in air; m/z = 17 – OH,


18

100 200 300 400 500 600 700

-50

-40

-30

-20

-10

0

-0.4

-0.3

-0.2

-0.1

0.0

-20

0

20

40

60

80

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.00

0.02

0.04

0.06

0.08

100 200 300 400 500 600 700

100 200 300 400 500 600 700

639°C

584°C

94°C 629°C

-8.5%(628°- 750°C)

-35.6%(311°- 628°C)

94°C

-0.8%(30°- 311°C)

<+

>

<+

>

<+

>

TG

m

/%

Temperature / °C

-->

exo


)

0.00

0.05

0.10

0.15

0.20

94°C


631°C

631°C

17+

592°C

94°C

592°C

592°C


18+

44+


Inte

nsity o

f m

=1

7,1

8/A

*E-5

0.00

0.01

0.02

0.03

0.04

0.05

200°C

592°C

587°C

130°C

130°C

98+

58+

43+

Inte

nsity o

f m

=4

3/A

*E-7

0.000

0.002

0.004

0.006

0.008

0.010



19

100 200 300 400 500 600 700

-60

-50

-40

-30

-20

-10

0

-1.2

-1.0

-0.8

-0.6

-0.4

-0.2

0.0

-10

0

10

20

30

40

50

60

70

80

0.0

0.2

0.4

0.6

0.8

1.0

0.0

0.5

1.0

1.5

2.0

2.5

3.0

100 200 300 400 500 600 700

100 200 300 400 500 600 700

<+

>

-34.7%(412°- 532°C)

447

°C

565

°C5

48

°C

512

°C

447

°C

512

°C

84°C

548

°C

-14.8%(532°- 750°C)

90°C

-1.5%(30°- 412°C)

<+

>

<+

>

TG

m

/%

Temperature / °C

-->

exo


)

0.0

0.1

0.2

0.3

0.4

0.5

0.65

48

°C

447

°C

482

°C

89°C


447

°C

527

°C

17+

527

°C

89°C

548

°C5

48

°CIntensity of m=44/ A*E

-6

18+

44+


Inte

nsity o

f m

=1

7,1

8/A

*E-6

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

304

°C

548

°C513

°C

316

°C

497

°C

154

°C

98+

58+

43+

Inte

nsity o

f m

=4

3/A

*E-9

0

1

2

3

4

5

6



20

100 200 300 400 500 600 700

-70

-60

-50

-40

-30

-20

-10

0

-1.0

-0.8

-0.6

-0.4

-0.2

0.0

-20

-10

0

10

20

30

40

50

60

70

80

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

0.0

0.5

1.0

1.5

2.0

100 200 300 400 500 600 700

100 200 300 400 500 600 700

-41.6%(432°- 617°C)

<+

>

631°C

573°C

589°C

81°C

618°C

-14.4%(617°- 750°C)

94°C

-2.6%(30°- 432°C)

<+

>

<+

>

TG

m

/%

Temperature / °C

-->

exo


)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

627°C

77°C


17+

597°C

78°C

599°C

597°C


18+

44+


Inte

nsity o

f m

=1

7,1

8/A

*E-6

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

598°C

108°C

584°C

126°C

98+

58+

43+

Inte

nsity o

f m

=4

3/A

*E-8

0

1

2

3

4

5

6

7



21

Table S2. Crystallographic data.

Fe-ICR-5 Fe-ICR-7 Al-ICR-4

Formula Fe P2 O4 C14 H8 Fe2 P6 O12 C72 H54 Al P3 O6 C27 H21

a 20.9756(5) 25.0617(14) 17.20746(15)

b 5.09529(18) 25.0617(14) 17.20746(15)

c 13.9702(3) 9.5901(6) 9.39191(14)

β 108.6297(11) - -

Volume 1414.86(7) 5216.5(5) 2408.34(5)

Crystal system monoclinic trigonal trigonal

Space group P21/a P-3 P-3

Rp 1.63 2.99 3.37

Rwp 2.49 4.25 2.79

GOF 3.43 3.69 2.73

Figure S15. Final Rietveld fit of Fe-ICR-5. Black dots – measured data, red line – calculated

profile, blue line – difference curve.

22



Figure S17. Final Rietveld fit of Al-ICR-4. Black dots – measured data, red line – calculated


23



24

Figure S19. Comparison of the crystal structures of Fe-ICR-3 (top)3 and Fe-ICR-5 (bottom,

this paper).

25

Figure S20. Comparison of PXRD patterns of Al-ICR and Fe-ICR MOFs.

26

0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

0.0

0.5

1.0

1.5

2.0

Fe-ICR-4

Fe-ICR-2

d V

p / d

W (

Diffe

ren

tia

l P

ore

Are

a)

dp / nm

Figure S21. Pore size distribution of Fe-ICR-2 and Fe-ICR-4 calculated by the MP plot.

0 1 2 3 4 5 6 7 8 9 10

0.0

0.2

0.4

0.6Fe-ICR-7

Fe-ICR-6

d V

p / d

dp

dp / nm

Figure S22. Pore size distribution of Fe-ICR-6 and Fe-ICR-7 calculated using the NLDFT

method for cylindrical pores.

27

0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

0.0

0.5

1.0

1.5 Al-ICR-4

d V

p / d

W (

Diffe

ren

tia

l P

ore

Are

a)

dp / nm

Al-ICR-2

Figure S23. Pore size distribution of Al-ICR-2 and Al-ICR-4 calculated by the MP plot.

0 1 2 3 4 5 6 7 8 9 10

0.0

0.2

0.4

0.6

0.8

d V

p / d

dp

dp / nm

Al-ICR-6

Al-ICR-7

Figure S24. Pore size distribution of Al-ICR-6 and Al-ICR-7 calculated using the NLDFT

method for cylindrical pores.

28

4 6 8 10 12 14 16

Inte

nsity / a

. u

.

2 / o(Co K)

Fe-ICR-2

H2O

toluene

EtOH

Figure S25. PXRD patterns of as-synthetized Fe-ICR-2 (bottom) and Fe-ICR-2 after 24 h

treatment in H2O, EtOH, and toluene at room temperature. The diffractograms are vertically

shifted to avoid overlaps.

4 6 8 10 12 14 16

Fe-ICR-2

H2O reflux

EtOH reflux

toluene reflux

Inte

nsity / a

. u

.

2 / o(Co K)


treatment in boiling H2O, EtOH, and toluene. The diffractograms are vertically shifted to

avoid overlaps.

29

4 6 8 10 12 14 16

Inte

nsity/ a

. u

.

2 / o(Co K)

H2O activation

Fe-ICR-2

Figure S27. PXRD patterns of as-synthetized Fe-ICR-2 (bottom) and Fe-ICR-2 activated from

water. The diffractograms are vertically shifted to avoid overlaps.

4 6 8 10 12 14 16

2 / o(Co K)

Inte

nsity / a

. u

.

Fe-ICR-6

toluene

EtOH

H2O




30

4 6 8 10 12 14 16

Fe-ICR-6

H2O reflux

EtOH reflux

toluene reflux

2 / o(Co K)

Inte

nsity / a

. u

.

Figure S29. PXRD patterns of as-synthetized Fe-ICR-6 (bottom) and Fe-ICR-6 after 24 h in

boiling H2O, EtOH, and toluene. The diffractograms are vertically shifted to avoid overlaps.

4 6 8 10 12 14 16

Inte

nsity/ a

. u

.

2 / o(Co K)

Fe-ICR-6

H2O activation



31

4 6 8 10 12 14 16

Fe-ICR-7

Inte

nsity / a

. u

.

2 / o(Co K)

Fe-ICR-7

H2O

EtOH

toluene




4 6 8 10 12 14 16

toluene reflux

EtOH reflux

H2O reflux

Fe-ICR-7

Inte

nsity/ a

. u

.

2 / o(Co K)

Figure S32. PXRD patterns of as-synthetized Fe-ICR-7 and Fe-ICR-7 after 24 h treatment in

boiling H2O, EtOH, and toluene. The diffractograms are vertically shifted to avoid overlaps.

32

4 6 8 10 12 14 16

Inte

nsity / a

. u

.

2 / o(Co K)

H2O activation

Fe-ICR-7



2 4 6 8 10 12 14 16

Inte

nsity / a

. u

.

2 / o(Cu K)

toluene

EtOH

H2O

Al-ICR-2

Figure S34. PXRD patterns of as-synthetized Al-ICR-2 and Al-ICR-2 after 24 h treatment in

H2O, EtOH, and toluene at room temperature. The diffractograms are vertically shifted to

avoid overlaps.

33

2 4 6 8 10 12 14 16

Inte

nsity / a

. u

.

2 / o(Cu K)

Al-ICR-2

H2O reflux

EtOH reflux

toleune reflux

Figure S35. PXRD patterns of as-synthetized Al-ICR-2 (bottom) and Al-ICR-2 after 24 h


avoid overlaps.

2 4 6 8 10 12 14 16

Inte

nsity/ a

. u

.

2 / o(Cu K)

Al-ICR-2

H2O activation

Figure S36. PXRD patterns of as-synthetized Al-ICR-2 (bottom) and Al-ICR-2 activated from


34

2 4 6 8 10 12 14 16

2 / o(Cu K)

In

ten

sity / a

. u

.

Al-ICR-6

H2O

EtOH

toluene


treatment in H2O, EtOH, and toluene at RT. The diffractograms are vertically shifted to avoid

overlaps.

2 4 6 8 10 12 14 16

2 / o(Cu K)

Al-ICR-6

H2O reflux

EtOH reflux

toluene reflux

In

ten

sity / a

. u

.



avoid overlaps.

35

2 4 6 8 10 12 14 16

Inte

nsity / a

. u

.

2 / o(Cu K)

Al-ICR-6

H2O activation



2 4 6 8 10 12 14 16

Inte

nsity / a

. u

.

2 / o(Cu K)

Al-ICR-7

toluene

EtOH

H2O


treatment in H2O, EtOH, and toluene at RT. The diffractograms are vertically shifted to avoid

overlaps.

36

2 4 6 8 10 12 14 16

Al-ICR-7

H2O reflux

EtOH reflux

toluene reflux

Inte

nsity / a

. u

.

2 / o(Cu K)

Figure S41. PXRD patterns of as-synthetized Al-ICR-7 (bottom) nad Al-ICR-7 after 24 h


avoid overlaps.

2 4 6 8 10 12 14 16

Inte

nsity / a

. u

.

2 / o(Cu K)

H2O activation

Al-ICR-7



37

0.0 0.2 0.4 0.6 0.8 1.0

0

200

400

600

Vc

m3 (

ST

P)

g-1

p / p0

Al-ICR-2

Al-ICR-4

Al-ICR-6

Al-ICR-7

Figure S43. Nitrogen adsorption isotherms of as-synthetized Al-ICR-2, Al-ICR-4, Al-ICR-6,

and Al-ICR-7.

0.0 0.2 0.4 0.6 0.8 1.0

0

200

400

600

800

Vc

m3 (

ST

P)

g-1

p / p0

Fe-ICR-2

H2O

EtOH

toluene

Figure S44. Nitrogen adsorption isotherms of as-synthetized Fe-ICR-2 (black) and Fe-ICR-2

after 24 h treatment in H2O, EtOH, and toluene at RT.

38

0.0 0.2 0.4 0.6 0.8 1.0

0

200

400

600

800

Vc

m3 (

ST

P)

g-1

p / p0

Fe-ICR-2

H2O reflux

EtOH reflux

toluene reflux


after 24 h treatment in boiling H2O, EtOH, and toluene.

0.0 0.2 0.4 0.6 0.8 1.0

0

200

400

600

800

1000

Vc

m3 (

ST

P)

g-1

p / p0

Fe-ICR-2

activated from H2O


activated from water.

39

0.0 0.2 0.4 0.6 0.8 1.0

0

200

400

600

800

1000

Vc

m3 (

ST

P)

g-1

p / p0

Fe-ICR-6

H2O

EtOH

toluene



0.0 0.2 0.4 0.6 0.8 1.0

0

200

400

600

800

1000

1200

Vc

m3 (

ST

P)

g-1

p / p0

Fe-ICR-6

H2O reflux

EtOH reflux

toluene reflux



40

0.0 0.2 0.4 0.6 0.8 1.0

0

200

400

600

800

Vc

m3 (

ST

P)

g-1

p / p0

Fe-ICR-6

activated fromH2O



0.0 0.2 0.4 0.6 0.8 1.0

0

200

400

600

800

1000

Vc

m3 (

ST

P)

g-1

p / p0

Fe-ICR-7

H2O

EtOH

toluene



41

0.0 0.2 0.4 0.6 0.8 1.0

0

200

400

600

800

1000

Vc

m3 (

ST

P)

g-1

p / p0

Fe-ICR-7

H2O reflux

EtOH reflux

toluene reflux



0.0 0.2 0.4 0.6 0.8 1.0

0

200

400

600

800

1000

Vc

m3 (

ST

P)

g-1

p / p0

Fe-ICR-7

activated from H2O



42

0.0 0.2 0.4 0.6 0.8 1.0

0

200

400

600

800

Vc

m3 (

ST

P)

g-1

p / p0

Al-ICR-2

H2O

EtOH

toluene

Figure S53. Nitrogen adsorption isotherms of as synthetized Al-ICR-2 (black) and Al-ICR-2


0.0 0.2 0.4 0.6 0.8 1.0

-100

0

100

200

300

400

500

600

700

800

900

Vc

m3 (

ST

P)

g-1

p / p0

Al-ICR-2

H2O reflux

EtOH reflux

toluene reflux

Figure S54. Nitrogen adsorption isotherms of as-synthetized Al-ICR-2 (black) and Al-ICR-2


43

0.0 0.2 0.4 0.6 0.8 1.0

0

200

400

600

800

Vc

m3 (

ST

P)

g-1

p / p0

Al-ICR-2

activated from H2O



0.0 0.2 0.4 0.6 0.8 1.0

0

200

400

600

800

1000

1200

1400

1600

1800

Vc

m3 (

ST

P)

g-1

p / p0

Al-ICR-6

H2O

EtOH

toluene



44

-0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1

0

200

400

600

800

1000

1200

1400

1600

1800

2000

Vc

m3 (

ST

P)

g-1

p / p0

Al-ICR-6

H2O reflux

EtOH reflux

toluene reflux



0.0 0.2 0.4 0.6 0.8 1.0

0

200

400

600

800

1000

1200

1400

Vc

m3 (

ST

P)

g-1

p / p0

Al-ICR-6

activated from H2O



45

0.0 0.2 0.4 0.6 0.8 1.0

0

200

400

600

800

1000

Vc

m3 (

ST

P)

g-1

p / p0

Al-ICR-7

H2O

EtOH

toluene



0.0 0.2 0.4 0.6 0.8 1.0

0

200

400

600

800

1000

Vc

m3 (

ST

P)

g-1

p / p0

Al-ICR-7

H2O reflux

EtOH reflux

toluene reflux



46

0.0 0.2 0.4 0.6 0.8 1.0

0

200

400

600

800

1000

Vc

m3 (

ST

P)

g-1

p / p0

Al-ICR-7

activated from H2O

Figure S61. Nitrogen adsorption isotherms of as synthetized Al-ICR-7 (black) and Al-ICR-7


47

Equations used for the analysis of adsorption properties of ICR MOFs

qe calculation from HPLC results:

𝑞𝑒 = (𝐶0−𝐶𝑒) 𝑉

𝑚 (1),

where qe is the adsorbed amount of BPA per unit mass of sorbent (mg g-1

), C0 and Ce are

initial concentration of BPA (mg L-1

) and measured equilibrium concentration of BPA (mg

L-1

), respectively, V is the total volume (L), and m is the weighted amount of adsorbent (g).

Pseudo-second order kinetic model:

𝑞𝑒 =𝑄𝑚

2 𝑘2 𝑡

1+𝑘2𝑄𝑚 (2),

where qe is calculated using Eq. (1) (mg g-1

), Qm is the amount of BPA adsorbed at the

equilibrium (mg g-1

), t is time of adsorption (min), and k2 stands for the pseudo-second order

rate constant (g mg-1

min-1

).1

Langmuir model:

𝑞𝑒 =𝐾𝐿𝑄𝑚𝐶𝑒

1+𝐾𝐿𝐶𝑒 (3),

where qe is calculated using Eq. (1), Qm is the Langmuir maximum sorption capacity (mg g-1

),

Ce stands for the BPA concentration at the equilibrium (measured, mg L-1

), and KL is the

Langmuir constant (L mg-1

) which is the measure of the affinity of adsorbate to adsorbent.4

Freundlich model:

𝑞𝑒 = 𝐾𝐹𝐶𝑒1/𝑛

(4),

where qe is given by Eq. (1), KF ([(mg g-1

) (mg L-1

)-n

]) stands for the Freundlich constant, Ce

is the BPA concentration at the equilibrium (mg L-1

), and n is a parameter which indicates a

degree of surface heterogeneity and is related to the sorption capacity.4,5

Langmuir-Freundlich model:

𝑞𝑒 = 𝑄𝑚𝐾𝐿𝐹𝐶𝑒

1/𝑛

1+𝐾𝐿𝐹𝐶𝑒1/𝑛 (5),

where qe is calculated using Eq. (1), Qm is the Langmuir-Freundlich maximum sorption

capacity (mg g-1

), Ce stands for the BPA concentration at the equilibrium (measured, mg L-1

),

and KLF (L mg-1

) with 1/n are the Langmuir-Freundlich constants.6,7

48

0 50 100 150 200 250 300 350100

125

150

175

200

225

250

AC

Al-ICR-2

Al-ICR-6

Al-ICR-7

qe / m

g g

-1

Time / min

Figure S62. Kinetic curves of BPA adsorption. Dots are experimental points obtained in

triplicate experiments and solid lines represent fits to the pseudo-second order kinetic model.

The equilibrium points were not used for the fitting (approximately > 100 min) as

recommended in literature.1 In the case of Al-ICR-6, the kinetic curve was fitted in entire

range because the equilibrium state was not reached within the recorded time.

49

0 10 20 30 40 50 60 700

50

100

150

200

250

300

350

Activated carbon

Langmuir isotherm

Freundlich isotherm

Langmuir-Freundlich isotherm

qe / m

g g

-1

Ce / mg L

-1

0 10 20 30 40 50 60 700

50

100

150

200

250

300

350

Al-ICR-2

Langmuir isotherm

Freundlich isotherm


qe / m

g g

-1

Ce / mg L

-1

0 20 40 60 80 100 1200

10

20

30

40

50

Al-ICR-4

Langmuir isotherm

Freundlich isotherm


qe / m

g g

-1

Ce / mg L

-1

0 10 20 30 40 50 60 700

50

100

150

200

250

300

350

Al-ICR-6

Langmuir isotherm

Freundlich isotherm


qe / m

g g

-1

Ce / mg L

-1

0 10 20 30 40 50 60 700

50

100

150

200

250

300

350

Al-ICR-7

Langmuir isotherm

Freundlich isotherm


qe / m

g g

-1

Ce / mg L

-1

Figure S63. Fitting of isotherms to the Langmuir, Freundlich, and Langmuir-Freundlich

adsorption models. Resulting parameters are given in Table S3. Only experimental points

with Ce > 0 were chosen for the fitting.

50

Table S3. Langmuir, Freundlich, and Langmuir-Freundlich parameters resulting from the

fitting (see Eqs. 1 – 5 for details).

Adsorbent Kinetic constants Langmuir constants

qm (mg g

-1)

k2 (g mg-1

min-1

)

R2 Qm

(mg g-1

)

KL

(L mg-1

)

R2

AC 183±2 0.022±0.001 0.987 221±4 0.81±0.04 0.984

Al-ICR-2 220±7 0.052±0.002 0.999 222±3 9.61±0.51 0.981

Al-ICR-4 n. a. n. a. n. a. 22±1 0.64±0.58 0.062

Al-ICR-6 194±4 0.010±0.002 0.938 326±8 0.15±0.01 0.993

Al-ICR-7 234±1 0.017±0.002 0.998 307±5 0.62±0.07 0.979

Adsorbent Freundlich constants Langmuir-Freundlich constants

KF

[(mg g-1

)

(mg L-1

)-n

]

n R2 Qm

(mg g-1

)

KLF

(L mg-1

)

n R2

AC 123±2 5.9±0.3 0.962 248±5 0.80±0.10 1.58±0.09 0.999

Al-ICR-2 165±2 12.1±0.6 0.973 239±2 2.28±0.11 3.10±0.17 0.999

Al-ICR-4 20±3 54.9±102 0.068 21±1 0.004±0.02 0.34±0.24 0.181

Al-ICR-6 63±4 2.4±0.1 0.958 340±23 0.15±0.01 1.07±0.10 0.992

Al-ICR-7 127±10 4.3±0.4 0.951 344±21 0.53±0.6 1.47±0.21 0.990

51

2 4 6 8 10 12 14 16 18 20

Al-ICR-7 after adsorption


Al-ICR-7 as synthetized



Inte

nsity / a

. u

.)

2 / o(Cu K)


Figure S64. Comparison of the PXRD patterns of Al-ICR MOFs before and after adsorption

of BPA and regeneration by acetone. Conditions of adsorption: 10 mg of adsorbent was mixed

with 50 mL of BPA solution, initial BPA concentration was 100 mg L-1

. The mixture was

stirred at constant temperature of 25 °C for 24 h. After the experiment, resulting adsorbent

was separated using centrifuge, washed twice by water and three times with acetone. The

solid was air-dried overnight, followed by standard activation and PXRD and N2 adsorption

measurement.

52

Table S4. Comparison of the specific surface areas of Al-ICR MOFs before and after

adsorption of BPA and regeneration by acetone.a

Adsorbent Specific surface area (m2 g

-1)

As-synthetized After adsorption

Al-ICR-2 b 933 915

Al-ICR-6 c 1362 1041

d

Al-ICR-7 c 1030 980

a Conditions of adsorption: 10 mg of adsorbent was mixed with 50 mL of BPA solution,

initial BPA concentration was 100 mg L-1

. The mixture was stirred at constant temperature of

25 °C for 24 h. After the experiment, resulting adsorbent was separated using centrifuge,

washed twice by water and three times with acetone. The solid was air-dried overnight,

followed by standard activation and PXRD and N2 adsorption measurement. b

Specific surface area calculated by the t-plot. c BET specific surface area.

d The decrease between as-synthetized and after adsorption and regeneration is in line with the

decrease observed after shaking in water at RT and therefore is not related to adsorption of

BPA.

53

Details of molecular modelling

Classical molecular simulations were used for evaluation of sorption properties and

interactions of BPA with Al-ICR-2, Al-ICR-6, and Al-ICR-7. The MOF supercells were

constructed on the bases of their Fe-ICR analogues. The cell parameters were taken from

crystallographic data. In the case of Al-ICR-2 we created the 1a x 2b x 3c supercell, and for

Al-ICR-6 and Al-ICR-7 we created 2a x 2b x 3c supercells, all containing 4 pores. Free

volume within the pores was calculated using water molecule as a probe with a radius of 1.44

Å (weighed average of the van der Waals radii taken from the Dmol3 program implemented

in the Materials Studio software: 1.72 Å for oxygen and 1.3Å for hydrogen).8 Each pore was

filled with corresponding amount of water (100, 312, and 250 water molecules for Al-ICR-2,

Al-ICR-6, and Al-ICR-7, respectively). Then, BPA molecules were placed into each pore (8

water molecules were replaced by one BPA). Since experimental measurements revealed high

concentrations of BPA adsorbed in the MOF structures, we carried out the calculations in the

following way: First, we created models containing single BPA (adsorbed amount qe ≈ 10 mg

g-1

) in the centre of each pore to find its binding sites and explore its behaviour at low

concentrations. Then, we created models containing amounts of BPA corresponding to qe ≈

100, 200, and 300 mg g-1

. For Al-ICR-2, we created only two models containing 7 or 14 BPA

molecules per supercell (corresponding to qe ≈ 100 and 200 mg g-1

) because higher

concentrations of BPA were not experimentally observed.

In the case of Al-ICR-6 and Al-ICR-7, the BPA loadings selected for qe ≈ 100, 200,

and 300 mg g-1

, i.e., 10, 20, or 31 BPA molecules per supercell of Al-ICR-6 and 14, 28, or 40

BPA molecules per supercell of Al-ICR-7. The initial positions of BPA molecules were

practically the same and close to the positions obtained in the simulations containing single

BPA molecule in each pore.

The geometry of all initial models was optimized and subsequent molecular dynamics

simulations in an NVT statistical ensemble at 300 K were carried out in the LAMMPS

simulation package.9 One dynamic step was 1 fs and 5 ∙ 10

6 steps were carried out. The

snapshots were collected every 10 ps and the snapshots of the last 1.5 ns were used for the

analyses. The charges of all MOFs were calculated using the Qeq method10

and all the

simulations were performed using the pcff forcefield.11

The electrostatic interactions were

calculated using the PPPM method, van der Waals interactions were calculated using the

Lennard-Jones potential with a cut-off distance of 12 Å. In all cases, the atomic positions in

the structures were kept fixed and the atomic positions of other atoms were variable.

54

The pores of ICR MOFs are not smooth. The organic linkers in Al-ICR-6 and Al-ICR-

7 form grooves whose dimensions approximately corresponds to the size of biphenyl (length

and width of 7 and 5 Å, respectively).

Figure S65 shows snapshots of two stable arrangements of BPA molecules in the Al-

ICR-6 pore containing a single molecule in each pore (qe ≈ 10 mg g-1

). The first position is

characteristic by the placement of BPA methyl groups above the groove with the OH

substituents aiming into the pore and one phenyl ring approximately parallel with the nearest

phenyl ring of the pore wall (Figure S65a,b). The second position is characterized by a close

contact of the pore wall and the BPA methyl groups (approximately 2.6 Å in average

measured between the nearest H atoms), and the connecting line of BPA OH substituents is

approximately perpendicular to the pore axis (Figure S65c,d). The interaction energy between

BPA and the Al-ICR-6 structure is of -19.1 kcal mol-1

in average for the first position (Figure

S65a,b) and of -22.0 kcal mol-1

in average for the second position (Figure S65c,d). The BPA

molecule changes these two positions during the simulations.

The situation is different in Al-ICR-7. The BPA molecule has a tendency to adopt a

close contact with the pore wall similarly to Al-ICR-6, but the presence of bulky phenyls

makes such contact impossible. These sterical reasons lead to a larger distance between the

pore wall and BPA molecule (Figure 5c). Then, the interaction energy is -18.2 ± 0.4 kcal

mol-1

, indicating that BPA has higher affinity to Al-ICR-6 at low concentrations.

The pore diameter of Al-ICR-2 is significantly smaller than the pores in Al-ICR-6 and

Al-ICR-7. A possible orientation of single BPA molecule within the Al-ICR-2 pore is shown

in Figure 5a. The size similarity of BPA molecule and the pore causes that the interaction

energy of -22.2 ± 0.4 kcal mol-1

is the strongest of all investigated ICR MOFs, indicating that

Al-ICR-2 is the best sorbent at low BPA concentrations (qe ≈ 10 mg g-1

).

55

Figure S65. Detailed view on the BPA arrangement inside the Al-ICR-6 pores along the pore

axis (left) and in the perpendicular direction to the pore axis (right). The biphenyl rings in

green are in the front and represent the bottom of the groove, methyl groups of BPA are in

blue and oxygen atoms are in red.

The BPA arrangement depends on the saturation of the pores. Figure S66 shows the

arrangement of BPA along the pore axis for qe ≈ 300 mg g-1

to visually compare the free pore

volumes of Al-ICR-6 and Al-ICR-7. The free volume after removing all water molecules is 74

% for Al-ICR-6 and 58 % for Al-ICR-7. If we take into account the absolute values of free

volume of Al-ICR-6 and Al-ICR-7, the free volume of Al-ICR-6 is about 50 % larger than in

the case of Al-ICR-7. The lower free volume of Al-ICR-7 leads to a more difficult penetration

of other BPA molecules into the pores and theoretically to a lower sorption capacity under the

same conditions.

Based on the simulation results we can conclude that the presence of different linkers

can tune the host-guest interactions especially for low qe values of BPA. With increasing BPA

concentrations the effects of linker sizes on the host-guest interactions gradually diminish and

maximal sorption capacity is given mainly by the free pore volume of ICR MOF.

56

Figure S66. Arrangement of BPA molecules with a loading of approximately 300 mg g-1

in

the pores of Al-ICR-6 (left) and Al-ICR-7 (right).

References

1 Simonin, J.-P. On the Comparison of Pseudo-First Order and Pseudo-Second Order Rate

Laws in the Modeling of Adsorption Kinetics. Chem. Eng. J., 2016, 300, 254-263. 2 JANA: https://doi.org/10.1515/zkri-2014-1737.

3 Hynek, J.; Brázda, P.; Rohlíček, J.; Londesborough, M. G. S.; Demel, J. Phosphinic Acid

Based Linkers: Building Blocks in Metal–Organic Framework Chemistry. Angew. Chem. Int.

Ed. 2018, 57, 5016 –5019. 4 Foo, K. Y.; Hameed, B. H. Insight into the Modeling of Adsorption Isotherm Systems.

Chem. Eng. J., 2010, 156, 2-10. 5 Kecili, R.; Hussain, Ch. M. Mechanism of Adsorption on Nanomaterials. Nanomaterials in

Chromatography, 2018, Chapter 4, 89-115. 6 Wang, S.; Vincent, T.; Faur, C.; Guibal E. A Comparison of Palladium Sorption Using

Polyethylenimine Impregnated Alginate-Based and Carrageenan-Based Algal Beads. Appl.

Sci. 2018, 8, 264-281. 7 Jeppu, G. P.; Clement. T. P. A Modified Langmuir-Freundlich Isotherm Model for

Simulating pH-Dependent Adsorption Effects. J. Contam. Hydrol., 2012, 129–130, 46–53. 8 Materials Studio Modeling Environment, Release 4.3 Documentation. Accelrys Software

Inc., San Diego, CA, 2003. 9 Plimpton, S. Fast Parallel Algorithms for Short-Range Molecular Dynamics. J. Comput.

Phys. 1995, 117, 1-19 10

Rappe, A. K.; Goddard III, W. A. Charge Equilibration for Molecular Dynamics

Simulations. J. Phys. Chem. 1991, 95, 3358-3363. 11

Sun, H.; Mumby, S. J.; Maple, J. R.; Hagler. A. T. An ab Initio CFF93 All-Atom Force

Field for Polycarbonates. J. Am. Chem. Soc. 1994, 116, 2978–2987.

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