Supplementary information for. Tuning the Swing Effect by Chemical Functionalisation of Zeolitic Imidazolate Frameworks

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1 Supplementary information for Tuning the Swing Effect by Chemical Functionalisation of Zeolitic Imidazolate Frameworks Claire L. Hobday a, Thomas D. Bennett b, David Fairen-Jimenez c, Alexander J. Graham a, Carole A. Morrison a, David R. Allan d, Tina Düren e and Stephen A. Moggach a a. EaStChem School of Chemistry and Centre for Science at Extreme Conditions, University of Edinburgh, David Brewster Road, Joseph Black Building, Edinburgh EH9 3FJ, UK b. Department of Materials Science and Metallurgy, University of Cambridge, CB3 0DZ, UK c. Department of Chemical Engineering & Biotechnology, University of Cambridge, CB2 3RA Cambridge, UK d. Diamond Light Source, Harwell Campus, Didcot, OX11 ODE, UK e. Centre for Advanced Separations Engineering, Department of Chemical Engineering, University of Bath, Bath, BA2 7AY, UK Contents SI-1:Synthesis and Methods... 2 Synthesis... 2 High-pressure crystallography... 2 DFT geometry optimisation and single point energy calculations... 3 Grand canonical Monte Carlo simulations... 4 SI-2 Crystallographic data of ZIF-90 and ZIF-65 at pressure... 7 SI-3 ZIF-65 geometry changes at pressure... 9 SI-4 Density functional theory calculations of linker rotations SI-5 Grand canonical Monte Carlo simulations of hypothetical ZIF phases SI-6 Crystallographic tables References S1

2 SI-1:Synthesis and Methods Synthesis Synthesis of ZIF-90. A solid mixture of zinc(ii) nitrate hexahydrate (0.07g, mol) and imidazole-2-carboxaldehyde ICA; g, mol) was dissolved in dimethylformamide (DMF) (3 ml) in a 12 ml Teflon-capped borosilicate vial. The vial was heated at a rate of 200 C h 1 to 100 C, held at this temperature for 18 h, and then cooled at a rate of 1 C h 1 to 90 C, then cooled to room temperature at 5 C h 1. The reaction DMF was exchanged for clean DMF several times. The orange crystals were retained in DMF before being analysed by SCXRD. Synthesis of ZIF-65. A solid mixture of zinc(ii) nitrate hexahydrate (0.03 g, mol) and 2-nitroimidazole NO 2 Im; g, mol) was dissolved in DMF (3 ml) in a 12 ml Teflon-capped borosilicate vial. The vial was heated at a rate of 200 C h 1 to 100 C, held at this temperature for 18 h, and then cooled at a rate of 1 C h 1 to 90 C, then cooled to room temperature at 5 C h 1. The reaction DMF was exchanged for clean DMF several times. The crystals were retained in DMF before being analysed by SCXRD. High-pressure crystallography Laboratory Data Collection and Reduction. Prior to high pressure (HP) experiments, ambient temperature and pressure diffraction data were collected on a laboratory diffractometer for both ZIF-90 and ZIF-65 in order to compare with the HP studies (which were also collected at room temperature). A single crystal was mounted onto a MiTiGen Microloops TM and a sphere of data were collected on a Bruker SMART APEX II diffractometer with graphite-monochromated Mo Kα radiation (λ= Å). These data were integrated using the program SAINT and the absorption correction was carried out using the program SADABS. 1,2 High-pressure Synchrotron Data Collection and Reduction. A single-crystal of both ZIF- 90 and ZIF-65 was placed in a modified Merrill-basset DAC 3 along with a ruby chip (for pressure calibration) 4,5 and surrounded by a MeOH:EtOH (4:1) mixture, in two separate experiments. Diffraction data were collected on station I19 at the Diamond Light Source, Rutherford Appleton Laboratory, on a Huber 4-circle goniometer with a Rigaku Saturn 724 S2

3 CCD detector using synchrotron radiation (λ = Å) from 0.14 GPa to 4.77 GPa for ZIF-65 and 0.11 GPa to 2.00 GPa for ZIF-90. Data were collected in ω scans, with a step size and exposure time of 0.3 and 1 s respectively. The data were integrated with the program SAINT using dynamic masks (these mask the regions of the detector which are shaded due to the pressure cell). 1 For ZIF-65, omission of shaded reflections, absorption correction and merging of data were carried out in a three-step process, firstly with the program SHADE, 6 SADABS 2 and finally XPREP. 7 For ZIF-90, as the crystals were twinned, data reduction was carried out using SHADE, 6 TWINABS 2 and XPREP. 7 Crystal Structure Refinements. Structure refinements were carried out in CRYSTALS. 8 The starting structures for refinement were taken from the ZIF-8, ZIF-90 and ZIF-65 structures deposited in the CSD (refcodes VELVOY, WOJGEI and GITTIN, respectively). 9 All structures were refined anisotropically against F 2. All 1,2 and 1,3 distances for the imidazole linker were restrained (ensuring the aromatic geometry of the ring was not distorted) whilst all torsion angles and metal ligand bond distances were allowed to freely refine. Vibrational and thermal similarity restraints were also applied to the organic linker. Hydrogen atoms on the linker were placed geometrically and to ride on their host atoms. The pore volume and electron count per unit cell were calculated using the SQUEEZE algorithm within PLATON using a probe radius and step size of 1.2 Å and 0.7 Å, respectively. 10 Care was taken in these refinements to treat all data sets in an identical manner to allow for a qualitative use of the SQUEEZE algorithm. DFT geometry optimisation and single point energy calculations These calculations were used to determine the potential energy surface with respect to the imidazole ring rotation for each framework. All calculations were performed using the CASTEP (version 5.11) simulation package. 11 The Hamiltonian operator was approximated using the Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional augmented with the Tkatchenko-Scheffler dispersion correction. The molecular wavefunction description was provided by on-the-fly pseudopotentials and a plane wave basis set operating at 650 ev, which gave convergence of the energy to within 4 mev per atom. The electronic structure was sampled at the gamma position only in the Brillouin zone due to the large size of the primitive unit cell (resulting in a k-point sampling grid of no greater than 0.06 Å -1 ). Before carrying out single point energy calculations of the functionalised imidazole ring rotation, the ambient crystal structures of the three frameworks were geometry optimised without any symmetry constraints to allow both the relaxation of the atomic positions and the unit cell S3

4 parameters. The potential energy surface was searched for energy minima by means of the Broyden-Fletcher-Goldfarb-Shanno (BFGS) algorithm. 12 Structures were considered to be optimised when the energy per atom, maximum force, maximum stress, and maximum atomic displacement converged to the values of 0.02 mev atom -1, 0.05 ev Å -1, 0.1 GPa, and Å, respectively. Once optimised, the co-ordinates of the respective imidazole linker were rotated through five degrees increments from ambient to 30, at each interval single point energy calculations were carried out at the same level of theory to the geometry optimisation. The optimised structures confirmed that the functionals used were appropriate as their root mean squared deviation (rmsd) and fluctuations in volume from the original crystal structures were minimal. 13 In addition there is a close correlation between experimental and simulated geometry of the ligands around the metal centre (see Figure S1). Any small changes could be attributed to small traces of solvent remaining in the experimental crystal structures which Figure S1: Overlays of the crystal structures (blue) with the DFT optimised structures (red) for (a) ZIF-65, (b) ZIF-90 and (c) ZIF-8. Note the small rmsd values and small percentages in volume changes which would be expected from a material with intrinsic flexibility. will direct the orientation of the imidazole orientation. Grand canonical Monte Carlo simulations Grand canonical Monte Carlo (GCMC) 14 simulations were performed in order to study methanol adsorption in ZIF-8, ZIF-65 and ZIF-90 using the multipurpose code MuSiC. 15 In S4

5 the GCMC simulations, the framework atoms were fixed at their crystallographic positions. For each ZIF, different simulations were carried out using high-pressure crystallographic structures to capture the effect of framework rotation with respect to increasing pressure during the adsorption process. Standard Lennard-Jones (LJ) 12-6 potentials were used to model the interatomic interactions between the framework and methanol. Apart from LJ interactions, electrostatic interactions were included for methanol-methanol and methanolframework interactions using the Wolf summation. 16 The parameters for the framework atoms were obtained from the UFF force field. 17 Methanol was modelled using the TraPPE potential. 18 The charges were taken from the DFT calculations (Table S1). The Lorentz- Berthelot mixing rules were employed to calculate fluid/solid parameters. Interactions beyond 15 Å were neglected Monte Carlo steps were performed, the first 40 % of which were used for equilibration, and the remaining steps were used to calculate the ensemble averages. To calculate the gas-phase fugacity the Peng-Robinson equation of state was used. 19 Table S1: Charges on frameworks for GCMC calculations, derived from DFT calculations Charges on frameworks atoms ZIF-65 Element Charge (e-) ZIF_H 0.05 ZIF_C ZIF_N ZIF_O ZIF_C 0.09 ZIF_N 0.19 ZIF_Zn 0.42 ZIF-90 Element Charge (e-) ZIF_H 0.03 ZIF_H 0.05 ZIF_C ZIF_C 0.05 ZIF_C 0.08 ZIF_O ZIF_N ZIF_Zn 0.41 ZIF-8 Element Charge (e-) ZIF_H ZIF_H ZIF_C ZIF_C S5

6 ZIF_C ZIF_N ZIF_Zn S6

7 SI-2 Crystallographic data of ZIF-90 and ZIF-65 at pressure Figure S2: PLATON SQUEEZE data showing void volume and pore content for (a) ZIF-90 and (b) ZIF-65 as a function of pressure. Red (left hand axis) shows evolution of void volume, and green (right hand axis) shows electron count in the void (in electrons per unit cell, e-/uc). S7

8 Table S2: Crystallographic changes in cell volume and θ as a function of increasing pressure in MeOH/EtOH for ZIF-8, ZIF-90 and ZIF-65 Pressure % θ / Pressure % θ / Pressure % θ / ZIF-8 change ZIF-90 change ZIF-65 change (MeOH/EtOH) in cell (MeOH/EtOH) in cell (MeOH/EtOH) in cell (GPa) volume (GPa) volume (GPa) volume * * * * S8

9 SI-3 ZIF-65 geometry changes at pressure Table S3: Selected distances in ZIF-65 crystal structures at pressure. Pressure (GPa) O(1) N(2) (x, -y, -z) (Å) O(1) N(1) (x, -y, -z) (Å) (4) 2.948(4) (6) 2.960(5) (6) 2.957(5) (8) 3.002(7) (8) 3.003(8) (9) 2.976(9) (9) 2.974(9) (9) 2.974(9) (10) 2.976(10) Figure S3: 4MR window in ZIF-65 as viewed down the a-axis at (a) ambient pressure and (b) 4.77 GPa. S9

10 SI-4 Density functional theory calculations of linker rotations Table S4: Results of single point energy calculation of ZIF-8, ZIF-90, ZIF-65 when θ is varied in 5 degree steps to explore the relative rotations from -30 to +30 degrees. Energies are shown in kj mol -1 relative rotation ( ) ZIF-65 ZIF-90 ZIF-8 absolute rotation Energy per relative absolute rotation rotation Energy per θ ( )* linker (kj mol -1 ) ( ) θ ( )* linker (kj mol -1 ) relative absolute rotation rotation ( ) θ ( )* Energy per linker (kj mol -1 ) S10

11 SI-5 Grand canonical Monte Carlo simulations of hypothetical ZIF phases Figure S4: Framework and methanol interaction energy histogram for ZIF-65-HP and ZIF-65-HYPO Figure S5: (a-d) ZIF-65-HP model (e-g) ZIF-65-HYPO model showing centres of mass of methanol as a function of their interaction energy with the framework. Where orange to -30 kj mol -1, red to -20 kj mol -1, blue to -8 kj mol -1, yellow - -8 to 0 kj mol -1. S11

12 Figure S6: Framework and methanol interaction energy histogram for ZIF-90-HP and ZIF-90-HYPO Figure S7: (a-c) ZIF-90-HP model (d-f) ZIF-90-HYPO model showing centres of mass of methanol as a function of their interaction energy with the framework. Where, red to -20 kj mol -1, blue to -8 kj mol -1, yellow - -8 to 0 kj mol -1. S12

13 SI-6 Crystallographic tables Crystal data (zif65_ambient) (zif65-11kbar) (zif65-31kbar) (zif65-73kbar) Chemical formula (C 6H 4N 6O 4Zn)n3.6n(CH3OH) (C 6H 4N 6O 4Zn)nn 1.46(CH3OH) (C 6H 4N 6O 4Zn)nn 1.58(CH3OH) (C 6H 4N 6O 4Zn)nn 1.63(CH3OH) M r Crystal system, space group Cubic, I43m Cubic, I43m Cubic, I43m Cubic, I43m Temperature (K) a (Å) (2) (3) (19) (3) V (Å 3 ) (18) 5231 (3) (17) (3) Z Radiation type Mo Kα Mo Kα Mo Kα Mo Kα µ (mm 1 ) Crystal size (mm) Data collection Diffractometer Bruker Kappa Apex2 Bruker Kappa Apex2 Bruker Kappa Apex2 Bruker Kappa Apex2 Absorption correction T min, T max 0.60, , , , 0.65 No. of measured, independent and observed [I > 2.0σ(I)] reflections 27896, 1020, , 888, , 892, , 817, 686 R int θ max ( ) (sin θ/λ) max (Å 1 ) Refinement R[F 2 > 2σ(F 2 )], wr(f 2 ), S 0.051, 0.091, , 0.105, , 0.094, , 0.144, 0.83 No. of reflections No. of parameters No. of restraints H-atom treatment Δρ max, Δρ min (e Å 3 ) 1.06, , , , 0.27 Absolute structure Flack (1983), 457 Friedel-pairs Flack (1983), 394 Friedel-pairs Flack (1983), 396 Friedel-pairs Flack (1983), 361 Friedel-pairs Absolute structure parameter 0.00 (2) (19) (16) 0.15 (2) (zif65-141kbar) (zif65-216kbar) (zif65-294kbar) (zif65-393kbar) S13

14 Crystal data Chemical formula (C 6H 4N 6O 4Zn)n1.92n(CH3OH) (C 6H 4N 6O 4Zn)nn 2.53(CH3OH) (C 6H 4N 6O 4Zn)nn 2.75(CH3OH) (C 6H 4N 6O 4Zn)nn 2.83 M r Crystal system, space group Cubic, I43m Cubic, I43m Cubic, I43m Cubic, I43m Temperature (K) a (Å) (4) (9) (5) (17) V (Å 3 ) (4) (8) (4) (15) Z Radiation type Mo Kα Synchrotron, λ = Å Synchrotron, λ = Å Synchrotron, λ = Å µ (mm 1 ) Crystal size (mm) Data collection Diffractometer Bruker Kappa Apex2 Unknown Unknown Unknown Absorption correction T min, T max 0.56, , , , 0.64 No. of measured, independent and observed [I > 2.0σ(I)] reflections 12925, 718, , 642, , 857, , 561, 445 R int θ max ( ) (sin θ/λ) max (Å 1 ) Refinement R[F 2 > 2σ(F 2 )], wr(f 2 ), S 0.059, 0.160, , 0.200, , 0.203, , 0.196, 0.94 No. of reflections No. of parameters No. of restraints H-atom treatment Δρ max, Δρ min (e Å 3 ) 0.69, , , , 0.53 Absolute structure Flack (1983), 317 Friedel-pairs Flack (1983), 282 Friedel-pairs Flack (1983), 381 Friedel-pairs Flack (1983), 246 Friedelpairs Absolute structure parameter 0.17 (3) 0.23 (3) 1.16 (3) 1.25 (3) (zif65-477kbar) (zif90_ambient) (zif90-34kbar) (zif90-88kbar) Crystal data Chemical formula (C 6H 4N 6O 4Zn)nn 2.73(CH3OH) C 8H 6N 4O 2Zn (C 8H 12N 4O 2Zn)n 15(CH3OH) (C 8H 3N 4O 2Zn)n2n(CH3OH) S14

15 M r Crystal system, space group Cubic, I43m Cubic, I43m Cubic, I43m Cubic, I43m Temperature (K) a (Å) (16) (11) (7) (9) V (Å 3 ) (14) (9) (6) (8) Z Radiation type Mo Kα Mo Kα Mo Kα Mo Kα µ (mm 1 ) Crystal size (mm) Data collection Diffractometer Unknown Bruker Kappa Apex2 Bruker Kappa Apex2 Bruker Kappa Apex2 Absorption correction T min, T max 0.53, , , , 0.73 No. of measured, independent and observed [I > 2.0σ(I)] reflections 11949, 411, , 840, , 170, , 315, 278 R int θ max ( ) (sin θ/λ) max (Å 1 ) Refinement R[F 2 > 2σ(F 2 )], wr(f 2 ), S 0.074, 0.209, , 0.463, , 0.105, , 0.270, 0.96 No. of reflections No. of parameters No. of restraints H-atom treatment not refined Δρ max, Δρ min (e Å 3 ) 0.70, , , , 0.53 Absolute structure Flack (1983), 178 Friedel-pairs Flack (1983), 374 Friedelpairs Flack (1983), 0 Friedel-pairs Flack (1983), 133 Friedel-pairs Absolute structure parameter 0.20 (3) 0.16 (4) 0.02 (5) 0.05 (17) (zif90-148kbar) (zif90-195kbar) Crystal data Chemical formula (C 8H 6N 4O 2Zn)nn 5(CH3OH) (C 8H 6N 4O 2Zn)nn 5.6(CH3OH) M r Crystal system, space group Cubic, I43m Cubic, I43m S15

16 Temperature (K) a (Å) (17) (2) V (Å 3 ) (15) 5076 (2) Z Radiation type Synchrotron, λ = Å Mo Kα µ (mm 1 ) Crystal size (mm) Data collection Diffractometer Unknown Unknown Absorption correction T min, T max 0.47, , 0.65 No. of measured, independent and observed [I > 2.0σ(I)] reflections 6212, 403, , 184, 135 R int θ max ( ) (sin θ/λ) max (Å 1 ) Refinement R[F 2 > 2σ(F 2 )], wr(f 2 ), S 0.124, 0.289, , 0.621, 1.02 No. of reflections No. of parameters No. of restraints H-atom treatment not refined not refined Δρ max, Δρ min (e Å 3 ) 0.89, , 2.22 Absolute structure Flack (1983), 0 Friedel-pairs Flack (1983), 0 Friedel-pairs Absolute structure parameter 0.24 (4) 0.7 (15) References (1) Bruker; SAINT, Ed. Madison, Wisconsin, USA, (2) Sheldrick, G. M. University of Göttingen, Germany., (3) Moggach, S. A.; Allan, D. R.; Parsons, S.; Warren, J. E. J. Appl. Cryst. 2008, 41, 249. (4) Forman, R. A.; Block, S.; Barnett, J. D.; Piermarini, G. Science 1972, 176, 284. S16

17 (5) Piermarini, G. J.; Block, S.; Barnett, J. D.; Forman, R. A. J. Appl. Phys. 1975, 46, (6) Parsons, S.; University of Edinburgh: Edinburgh, Scotland, (7) Bruker; XPREP, Ed. Madison, Wisconsin, USA, (8) Betteridge, P. W.; Carruthers, J. R.; Cooper, R. I.; Prout, K.; Watkin, D. J. J. Appl. Cryst. 2003, 36, (9) Park, K. S.; Ni, Z.; Côté, A. P.; Choi, J. Y.; Huang, R.; Uribe-Romo, F. J.; Chae, H. K.; O Keeffe, M.; Yaghi, O. M. Proc. Natl. Acad. Sci. U.S.A 2006, 103, (10) Spek, A. L. J. Appl. Cryst. 2003, 36, 7. (11) Clark, S. J.; Segall, M. D.; Pickard, C. J.; Hasnip, P. J.; Probert, M. I. J.; Refson, K.; Payne, M. C. Z. Kristallogr. 2005, 220, 567. (12) Shanno, D. F. Math. Comput. 1970, 24, 647. (13) Macrae, C. F.; Bruno, I. J.; Chisholm, J. A.; Edgington, P. R.; McCabe, P.; Pidcock, E.; Rodriguez-Monge, L.; Taylor, R.; van de Streek, J.; Wood, P. A. J. Appl. Cryst. 2008, 41, 466. (14) Frenkel, D.; Smit, B. Understanding molecular simulation from algorithms to applications; Second ed.; Academic Press: San Diego, , 29. (15) Gupta, A.; Chempath, S.; Sanborn, M. J.; Clark, L. A.; Snurr, R. Q. Mol. Simul. 2003, (16) Wolf, D.; Keblinski, P.; Phillpot, S. R.; Eggebrecht, J. J. Chem. Phys. 1999, 110, (17) Rappe, A. K.; Casewit, C. J.; Colwell, K. S.; Goddard, W. A.; Skiff, W. M. J. Am. Chem. Soc. 1992, 114, (18) Chen, B.; Potoff, J. J.; Siepmann, J. I. J Phys Chem B 2001, 105, (19) Peng, D.; Robinson, D. B. Ind Eng Chem Fund 1976, 15, 59. S17