Postsynthetic Ligand Insertion
4.2. Experimental section
4.2.3. Crystallographic data collection and refinement of the structures
Crystals of 1, 2, 3, and 5 were coated with paratone-N oil and the diffraction data measured at 298 K with synchrotron radiation ( = 0.700 or 0.800 Å) on a ADSC Quantum-210 detector at 2D SMC with a silicon (111) double crystal monochromator (DCM) at the Pohang Accelerator Laboratory, Korea. The PAL BL2D-SMDC Program11 was used for data collection and HKL3000sm (Ver. 703r)12 was used for cell refinement, reduction and absorption correction. A crystal of 4 was coated with paratone oil and the diffraction data measured at 173 K with Mo K radiation on an X-ray diffraction camera system using an imaging plate equipped with a graphite crystal incident beam monochromator. The RapidAuto software13 was used for data collection and data processing. All structures were solved by direct method and refined by full-matrix least-squares calculation with the SHELX software package.14
1, [Ag3(BTB)(H2O)0.70]. Three silver atoms, one BTB ligand and a ligated water molecule with 0.70 site occupancy are observed as an asymmetric unit. All non-hydrogen atoms are refined anisotropically;
the hydrogen atoms were assigned isotropic displacement coefficients U(H) = 1.2U (C), their coordinates were allowed to ride on their respective atoms. The final refinement was performed with the modification of the structure factors for the electron densities of the disordered solvents (3507.9 Å3
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(45.4% of the total unit cell volume); 621 electrons correspond to ~16 DMF molecules per unit cell) using the SQUEEZE option of PLATON.15 Refinement converged at a final R1 = 0.0797 and wR2 = 0.2286 for 3397 reflections with I > 2(I); R1 = 0.1299 and wR2 = 0.2684 for all 7572 reflections. The largest difference peak and hole were 0.941 and 0.537 e·Å3, respectively.
2, [Ag6(BTB)2(dpey)0.75]. Six silver atoms, two BTB ligands, one dpey linker at a Wyckoff position 2b of site symmetry 2 with 0.96 site occupancy, the other dpey linker at a Wyckoff position 2a of site symmetry 2 with 0.55 site occupancy, and two DMF sites of a total of 1.37 site occupancies are observed as an asymmetric unit. All non-hydrogen atoms are refined anisotropically; the hydrogen atoms were assigned isotropic displacement coefficients U(H) = 1.2U (C), their coordinates were allowed to ride on their respective atoms. The least-squares refinement of the structural model was performed under displacement parameter restraints such as DELU, DFIX, FLAT, ISOR, and SIMU. The final refinement was performed with the modification of the structure factors for the electron densities of the disordered solvents (1298 Å3 (17.7% of the total unit cell volume); 235 electrons correspond to ~5.9 DMF molecules per unit cell) using the SQUEEZE option of PLATON.15 Refinement converged at a final R1
= 0.0783 and wR2 = 0.2595 for 7322 reflections with I > 2(I); R1 = 0.1041 and wR2 = 0.2594 for all 10393 reflections. The largest difference peak and hole were 2.222 and 1.090 e·Å3, respectively.
3, [Ag6(BTB)2(dpee)0.84]. Six silver atoms, two BTB ligands, one dpee linker at a Wyckoff position 2b of site symmetry 2, the other dpee linker at a Wyckoff position 2a of site symmetry 2 with 0.78 site occupancy, and two DMF molecules are observed as an asymmetric unit. All non-hydrogen atoms are refined anisotropically; the hydrogen atoms were assigned isotropic displacement coefficients U(H) = 1.2U (C), their coordinates were allowed to ride on their respective atoms. The least-squares refinement of the structural model was performed under displacement parameter restraints such as DFIX, DANG, FLAT, ISOR and SIMU. The final refinement was performed with the modification of the structure factors for the electron densities of the disordered solvents (1227.5 Å3 (17.0% of the total unit cell volume); 405 electrons correspond to ~10 DMF molecules per unit cell) using the SQUEEZE option of PLATON.15 Refinement converged at a final R1 = 0.0957 and wR2 = 0.2582 for 5793 reflections with I > 2(I); R1 = 0.1956 and wR2 = 0.3198 for all 13741 reflections. The largest difference peak and hole were 1.474 and 1.008 e·Å3, respectively.
[Ag6(BTB)2(dpt)0.74]. Six silver atoms, two BTB ligands, one dpt linker with 0.74 site occupancy, and three DMF sites of a total of 1.69 site occupancies are observed as an asymmetric unit. All non-hydrogen atoms are refined anisotropically; the hydrogen atoms attached to the ligands were assigned isotropic displacement coefficients U(H) = 1.2U (C) and their coordinates were allowed to ride on their respective atoms. The least-squares refinement of the structural model was performed under displacement parameter restraints such as DFIX, DANG, FLAT, ISOR, DELU, and SIMU. The final refinement was performed with the modification of the structure factors for the electron densities of the disordered solvents (1213 Å3 (15.6% of the total unit cell volume); 642 electrons correspond to ~16 DMF
87
molecules per unit cell) using the SQUEEZE option of PLATON.15 Refinement of the structure converged at a final R1 = 0.1626, wR2 = 0.3747 for 7478 reflections with I > 2(I); R1 = 0.2737, wR2
= 0.4366 for all 17176 reflections. The largest difference peak and hole were 7.089 and 1.995 e·Å3, respectively.
[Ag3(BTB)(bpy)0.80]. Three silver atoms, one BTB ligand, one bpy linker with 0.80 site occupancy, and one DMF molecule are observed as an asymmetric unit. All non-hydrogen atoms are refined anisotropically; the hydrogen atoms were assigned isotropic displacement coefficients U(H) = 1.2U (C), their coordinates were allowed to ride on their respective atoms. The least-squares refinement of the structural model was performed under displacement parameter restraints such as DFIX, DANG, FLAT, ISOR, DELU, and SIMU. The final refinement was performed with the modification of the structure factors for the electron densities of the disordered solvents (888 Å3 (11.4% of the total unit cell volume);
150 electrons correspond to ~3.8 DMF molecules per unit cell) using the SQUEEZE option of PLATON.15 Refinement converged at a final R1 = 0.0491 and wR2 = 0.1510 for 5905 reflections with I > 2(I); R1 = 0.0602 and wR2 = 0.1594 for all 7566 reflections. The largest difference peak and hole were 1.028 and 1.103 e·Å3, respectively.
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Table 4.1. Crystal data and structure refinement for AgBTB, 1.
Empirical formula C216H131.20O53.60Ag24
Formula weight 6172.88
Temperature 298(2) K
Wavelength 0.700 Å
Crystal system Monoclinic
Space group C2/c
Unit cell dimensions a = 45.140(9) Å α = 90°
b = 5.9340(12) Å β = 122.76(3)°
c = 34.285(7) Å γ = 90°
Volume 7723(3) Å3
Z 1
Density (calculated) 1.327 Mg/m3
Absorption coefficient 1.452 mm-1
F(000) 2984
Crystal size 0.170 x 0.110 x 0.022 mm3
Theta range for data collection 2.783 to 25.997°.
Index ranges 56<=h<=56, 7<=k<=7, 38<=l<=41
Reflections collected 23073
Independent reflections 7572 [R(int) = 0.0931]
Completeness to theta = 24.835° 96.2 %
Absorption correction Semi-empirical from equivalents Max. and min. transmission 0.969 and 0.790
Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 7572 / 7 / 288
Goodness-of-fit on F2 0.927
Final R indices [I>2sigma(I)] R1 = 0.0797, wR2 = 0.2286
R indices (all data) R1 = 0.1299, wR2 = 0.2684
Extinction coefficient 0.0011(2)
Largest diff. peak and hole 0.941 and 0.537 e·Å3
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Table 4.2. Crystal data and structure refinement for AgBTB-dpey, 2.
Empirical formula C264.7H180N10.8O53.5Ag24
Formula weight 6956.66
Temperature 296(2) K
Wavelength 0.700 Å
Crystal system Monoclinic
Space group C2
Unit cell dimensions a = 41.599(8) Å α = 90°
b = 6.2570(13) Å β = 125.38(3)°
c = 34.592(7) Å γ = 90°
Volume 7341(3) Å3
Z 1
Density (calculated) 1.574 Mg/m3
Absorption coefficient 1.538 mm-1
F(000) 3400
Crystal size 0.058 x 0.052 x 0.021 mm3
Theta range for data collection 1.697 to 23.198°.
Index ranges 46<=h<=46, 7<=k<=7, 36<=l<=36
Reflections collected 20422
Independent reflections 10393 [R(int) = 0.0381]
Completeness to theta = 23.198° 94.0 %
Absorption correction Semi-empirical from equivalents Max. and min. transmission 0.968 and 0.916
Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 10393 / 212 / 845
Goodness-of-fit on F2 0.999
Final R indices [I>2sigma(I)] R1 = 0.0783, wR2 = 0.2295
R indices (all data) R1 = 0.1041, wR2 = 0.2594
Absolute structure parameter 0.41(9)
Largest diff. peak and hole 2.222 and 1.090 e·Å3
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Table 4.3. Crystal data and structure refinement for AgBTB-dpee, 3.
Empirical formula C282.7H211.6N15.1O56Ag24
Formula weight 7304.94
Temperature 296(2) K
Wavelength 0.800 Å
Crystal system Monoclinic
Space group C2
Unit cell dimensions a = 41.849(8) Å α = 90°
b = 6.2550(13) Å β = 126.65(3)°
c = 34.477(7) Å γ = 90°
Volume 7240(3) Å3
Z 1
Density (calculated) 1.675 Mg/m3
Absorption coefficient 2.241 mm-1
F(000) 3590
Crystal size 0.045 x 0.042 x 0.015 mm3
Theta range for data collection 1.998 to 33.401°.
Index ranges 52<=h<=51, 7<=k<=6, 44<=l<=44
Reflections collected 20690
Independent reflections 13741 [R(int) = 0.0561]
Completeness to theta = 28.685° 94.2 %
Absorption correction Semi-empirical from equivalents Max. and min. transmission 0.967 and 0.906
Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 13741 / 265 / 844
Goodness-of-fit on F2 1.012
Final R indices [I>2sigma(I)] R1 = 0.0957, wR2 = 0.2582
R indices (all data) R1 = 0.1956, wR2 = 0.3198
Absolute structure parameter 0.40(8)
Extinction coefficient 0.0019(3)
Largest diff. peak and hole 1.474 and 1.008 e·Å3
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Table 4.4. Crystal data and structure refinement for AgBTB-dpt, 4.
Empirical formula C272H191N25O55Ag24
Formula weight 7278.37
Temperature 173(2) K
Wavelength 0.71073 Å
Crystal system Monoclinic
Space group P21/n
Unit cell dimensions a = 45.113(9) Å α = 90°
b = 5.9589(12) Å β = 123.31(3)°
c = 34.512(7) Å γ = 90°
Volume 7753(3) Å3
Z 1
Density (calculated) 1.559 Mg/m3
Absorption coefficient 1.545 mm-1
F(000) 3566
Crystal size 0.170 x 0.100 x 0.070 mm3
Theta range for data collection 3.048 to 27.491°
Index ranges 58<=h<=58, 7<=k<=7, 44<=l<=44
Reflections collected 61308
Independent reflections 17176 [R(int) = 0.1774]
Completeness to theta = 25.242° 97.7 %
Absorption correction Semi-empirical from equivalents Max. and min. transmission 0.900 and 0.779
Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 17176 / 522 / 902
Goodness-of-fit on F2 1.205
Final R indices [I>2sigma(I)] R1 = 0.1626, wR2 = 0.3747
R indices (all data) R1 = 0.2737, wR2 = 0.4366
Largest diff. peak and hole 7.089 and 1.995 e·Å3
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Table 4.5. Crystal data and structure refinement for AgBTB-bpy, 5.
Empirical formula C304.3H227.8N20.9O56.1Ag24
Formula weight 7663.54
Temperature 296(2) K
Wavelength 0.650 Å
Crystal system Monoclinic
Space group C2/c
Unit cell dimensions a = 44.850(9) Å α = 90°
b = 6.0020(12) Å β = 121.70(3)°
c = 33.950(7) Å γ = 90°
Volume 7775(3) Å3
Z 1
Density (calculated) 1.637 Mg/m3
Absorption coefficient 1.199 mm-1
F(000) 3777
Crystal size 0.080 x 0.070 x 0.020 mm3
Theta range for data collection 1.137 to 24.000°.
Index ranges 56<=h<=56, 7<=k<=7, 40<=l<=40
Reflections collected 27369
Independent reflections 7566 [R(int) = 0.0250]
Completeness to theta = 22.955° 95.0 %
Absorption correction Semi-empirical from equivalents Max. and min. transmission 0.976 and 0.910
Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 7566 / 72 / 408
Goodness-of-fit on F2 1.081
Final R indices [I>2sigma(I)] R1 = 0.0491, wR2 = 0.1510
R indices (all data) R1 = 0.0602, wR2 = 0.1594
Extinction coefficient 0.00181(18)
Largest diff. peak and hole 1.028 and 1.103 e·Å3
93 4.2.4. MOF preparations for gas sorption study
Before activation for gas sorption study all the samples were pre-exchanged using volatile MC to reduce the activation temperature since the samples lose their crystallinity during activation at a temperature higher than 50 ˚C. The activated 1a was prepared by vacuuming 1 pre-soaked in MC at room temperature for 1 d. The soakings of 2-5 in MC for room temperature activation lead to significant reduction of the amount of the corresponding dipyridyl ligands in the pore, hence the insertions of dipyridyl linkers are carried out in MC solution containing each dipyridyl ligand with 1 pre-soaked in MC (named as 1-MC). 2-MC, 3-MC, 4-MC and 5-MC were prepared soaking 1-MC in a 10 mL 1 mM or 2 mM solution of the corresponding dipyridyl linker in MC for two d. The procedure was repeated up to 4 times every two days using fresh dipyridyl linker solution and the sample was named as N-MC-n, where N is MOF number and n is repetition times of the soaking procedure. The activated samples for gas sorption experiments were prepared by vacuuming 2-MC-n, 3-MC-n, 4-MC-n and 5- MC-n at room temperature for 1 d and named as 2a-MC-n, 3a-MC-n, 4a-MC-n and 5a-MC-n, respectively. Before activation, all the samples were quickly washed by using 80 mL amount of fresh MC (20 mL × 4). The amount of dipyridyl linker was estimated using both the relative proton ratio of dipyridyl linker and BTB ligand in the 1H NMR spectrum of the sample digested in DMSO-d6 with aqueous either DCl or D2SO4 solution and EA after gas sorption experiments.
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