and BTB-based Porous Coordination Polymers with Open Metal Sites

Communication pubs.acs.org/crystal

pH-Dependent Interpenetrated, Polymorphic, Cd2+- and BTB-based Porous Coordination Polymers with Open Metal Sites Koya Prabhakara Rao, Masakazu Higuchi, Jingui Duan, and Susumu Kitagawa* Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan Institute for Integrated Cell-Materials Science (iCeMS), Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan S Supporting Information *

ABSTRACT: Two polymorphic porous coordination polymers constructed from Cd2+ and benzene-1,3,5-tribenzoate and having interpenetrated two-dimensional (2D) (6,3) net topology and three-dimensional (3D) (10,3)-b net topology structures were synthesized. The number of single honeycomb-type layers interpenetrated dictates the dimensionality of the crystal structures of these two phases. The 2D structure has two interpenetrated layers, whereas the 3D structure has four interpenetrated layers. Interestingly, these two polymorphic forms selectively adsorb CO2 over N2, C2H4, and C2H6. Moreover, diffuse reflectance Fourier-transform infrared spectroscopy of CO2 adsorbed on these two polymorphic phases indicates strong interaction between CO2 and the open metal sites present on Cd2+ ions.

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spectroscopy (DRIFTS). This study reveals that CO2 strongly interacts with OMSs present on Cd2+ ions. The [Cd 2 (HBTB) 2 (DMF)(MeOH)]·(DMF) 4 (MeOH)(DMA) (1 ⊃ solvent) (DMF = N,N-dimethylformamide; DMA = dimethylamine) phase was synthesized7 by the solvothermal reaction of Cd(NO3)2·6H2O and H3BTB in mixed solvents of DMF/MeOH (1:1). The pH of the reaction mixture was adjusted to 2.0 by the addition of a few drops of concd HNO3, and the whole reaction mixture was heated at 100 °C over a period of 48 h. [Cd(HBTB)(DMF)]·(DMF)2 (2 ⊃ solvent) phase was synthesized8 under similar solvothermal reaction conditions in mixed solvents of DMF/H2O/MeOH (2:1:1). The pH of the reaction mixture was adjusted to 6.0 by the addition of aqueous NaOH solution. The crystal structures of both 1 ⊃ solvent9 and 2 ⊃ solvent10 polymorphic phases were elucidated by single-crystal X-ray diffraction analysis (Figures 1−3). The asymmetric unit of the 1 ⊃ solvent phase comprises two Cd2+ ions, two BTB ligands, five DMF molecules (one coordinated and four uncoordinated), two MeOH molecules (one coordinated and one uncoordinated), and one DMA molecule (originating from DMF decomposition) (Figure S1 of the Supporting Information). Each Cd2+ ion is seven-coordinated11 (Figure 1a) and connected to six oxygen atoms of the three carboxylate (COO−) groups and a solvent molecule (DMF or MeOH) to form a hexagonal honeycomb-type Cd(HBTB) ⊃ solvent (6, 3) net in the ab plane (Figure 1b). Two such 1 ⊃ solvent (6, 3) nets

orous coordination polymers (PCPs) have been established1 as materials with great applications in gas storage, separation, catalysts, and sensors. Recent studies2 have demonstrated that PCPs with open metal sites (OMSs) have promising applications in gas storage, separation, and catalysis. In particular, OMSs play an important role in the case of gas separation,2b where a particular gas can strongly interact with the OMSs. Most PCPs reported so far lack OMSs after the removal of guest molecules. Nevertheless, in some PCPs, metal ions are coordinated to solvent molecules in pristine form, and they can be unstable after removing the guest molecules. In this context, PCPs with OMSs are valuable for various applications in the field of porous materials. PCPs bearing benzene-1,3,5-tribenzoic acid (H3BTB) as an organic linker and various metal ions have been extensively studied,3,4 and some exhibited exceptional porosity and sorption properties.3 A few Cd2+ ion and H3BTB coordination compounds with various secondary ligands possessing different structures and chemical compositions have been reported previously.5 Here, we report the synthesis, characterization, selective sorption properties, and Fourier-transform infrared (FT-IR) spectroscopy for carbon dioxide (CO2) adsorption of two polymorphic Cd2+-based and BTB-based PCPs. These PCPs have shown interpenetrated6 two-dimensional (2D) (6,3) net topology and three-dimensional (3D) (10,3)-b net topology structures, depending on the reaction conditions during synthesis. Moreover, the number of interpenetrated single layers dictates the structure dimensionalities of these two phases. The two polymorphic phases selectively adsorb CO2 over N2, C2H4, and C2H6. To elucidate the specific interactions of CO2 with these PCPs, we carry out diffuse reflectance FT-IR © 2013 American Chemical Society

Received: October 9, 2012 Revised: January 30, 2013 Published: January 31, 2013 981

dx.doi.org/10.1021/cg301476p | Cryst. Growth Des. 2013, 13, 981−985

Crystal Growth & Design

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Figure 1. Single-crystal X-ray structure of 1 ⊃ solvent. (a) Coordination environment of Cd2+, (b) [Cd(HBTB)] single-layer (6,3) net structure, (c) two interpenetrated layers, and (d) a 3D packing structure. (Hydrogen atoms and solvent molecules are omitted for clarity.)

Figure 2. Single-crystal X-ray structure of 2 ⊃ solvent (a) coordination environment of Cd2+, (b) 3D packing structure, (c) two interpenetrated eclipsed layers, (d) two interpenetrated staggered layers, (e) [Cd(HBTB)] single-layer structure, and (f) [Cd(HBTB)] singlelayer structure showing (10,3)-b net. (Hydrogen atoms and solvent molecules are omitted for clarity.)

interpenetrate exclusively in the ab plane to form a 2D layered structure as shown in Figure 1c. These interpenetrating layers are stacked along the c axis to form a 3D packing structure (Figure 1d), leaving one-dimensional (1D) channels along the c axis. Compound 1 has 2-fold parallel interpenetrated (6, 3) net topology, in which Cd2+ ions provides the three-connected nodes. The Cd−O bond lengths are in the range of 2.260(4)− 2.560(4) Å. The asymmetric unit of the 2 ⊃ solvent phase comprises one Cd2+ ion, one BTB ligand, and three DMF molecules (one coordinated and two uncoordinated) (Figure S2 of the Supporting Information). Similar to the case for 1 ⊃ solvent, the Cd2+ ion in 2 ⊃ solvent is seven-coordinated11 (Figure 2a) and connected to six oxygen atoms of the three carboxylate (COO−) groups and a solvent DMF molecule. In contrast to the case for 1 ⊃ solvent (6, 3) net topology, in the 2 ⊃ solvent compound, the Cd(HBTB) ⊃ solvent chains have (10,3)-b net12 topology (Figure 2f) giving rise to a 3D structure as shown in Figure 2e. Moreover, four such Cd(HBTB) ⊃ solvent (10,3)-b nets are interpenetrated three-dimensionally as shown in Figure 3, leaving 1D channels along the b axis. The topology and framework of the compound 2 ⊃ solvent is similar to the previously reported5b Cd(HBTB)(pyrrolidine-2yl-imidazole) compound. The Cd−O bond lengths are in the range of 2.214(3)−2.304(3) Å. Powder X-ray diffraction patterns of synthesized samples of the two polymorphic forms, 1 ⊃ solvent and 2 ⊃ solvent, were in reasonable agreement with the respective simulated patterns, indicating that the samples produced were phase pure (see Figure S3 of the Supporting Information). Unfortunately, upon degassing at 200 °C (the temperature used for activation prior to gas adsorption experiments), the powder X-ray diffraction patterns of the two phases lost their crystallinity (see Figure S4 of the Supporting Information). Major peaks in the patterns remained, while other peaks disappeared (see Figure S4 of the Supporting Information). Our attempts to degas at lower temperatures of 100, 150, and 175 °C provided powder patterns similar to that obtained at 200 °C, but thermogravimetric analysis (TGA) revealed that still more DMF solvent

Figure 3. Single-crystal X-ray 3D packing structure (space-filled model) of 2 ⊃ solvent, viewed along the b axis (center) and its four different interpenetrated layers. (Hydrogen atoms and solvent molecules are omitted for clarity.)

molecules were present. In this context, we choose to degas both phases at 200 °C and carried out adsorption measurements. TGA was carried out for homogeneous single-crystal crushed samples of 1 ⊃ solvent and 2 ⊃ solvent under flowing N2 (see Figure S5 of the Supporting Information). The two phases have similar TGA profiles (the expected weight losses are 24% and 22%, respectively); coordination-free solvent molecules are released below 70 °C in both the phases, and coordinated DMF molecules are removed starting at 130 °C. In 1 ⊃ solvent, one of the (CH3)2NH (DMA) already present in the compound could be converted to (CH3)2NH2+ by taking H+ from an unprotonated carboxylic group (−COOH) during the degas process. The second (CH3)2NH2+ might be generated from the decomposition of DMF during the degasing process. Similarly, in 2⊃Solvent, (CH3)2NH2+ might be generated from the decomposition of DMF. Unfortunately, 982



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(CH3)2NH2+ could not be removed before the compounds begin decomposing at 370 °C. Moreover, observed weight losses (23% and 22%) were in reasonable agreement with the expected weight losses (24% and 22%). Consequently, the chemical compositions of degassed phases 1 and 2 could be the same and are formulated according to single-crystal structures of raw phases, TGA, and FT-IR spectroscopy (Figure S6 of the Supporting Information) as ((CH3)2NH2)[Cd(BTB)]. Even though the structures of 1 and 2 were not particularly stable after the removal of the coordinated solvent DMF molecules, they still exhibited porous behavior. The permanent porosity of 1 and 2 was demonstrated by a type I isotherm for CO2 adsorption at 195 K (Figure 4). The compounds do not

understand the selective binding environment of CO2, we calculated isosteric heat of CO2 adsorption for 1 and 2 by virial analysis using CO2 adsorption isotherms measured at 195 and 210 K (Figures S7 and S8 of the Supporting Information). The isosteric heat of CO2 adsorption for 1 and 2, are −15 and −39 kJmol−1, respectively. To clarify the specific interactions of CO2 with OMSs present in phases 1 and 2, we carried out in situ DRIFTS. The background-subtracted FT-IR spectra of CO2 adsorbed on phases 1 and 2 at 195 K are shown in Figure 5.

Figure 5. FT-IR spectra (background subtracted) of CO2 adsorbed on phases 1 (top) and 2 (bottom) with increasing equilibrium pressure (measured at 1, 3, 5, 7, and 10 kPa) at 195 K.

Similar FT-IR peaks were observed for the two phases, except for the main components at 2336 and 2334 cm−1 for 1 and 2, respectively, with the same low-frequency shoulder at 2323 cm−1. This band can be readily assigned to the asymmetric stretching (ν3) mode of CO2 forming Cd2+· · ·OCO adducts with end-on configuration. The bands corresponding to the ν3 mode of CO2 are red-shifted by Δν = −13 and −15 cm−1, respectively, for phases 1 and 2, with respect to the gas phase (2349 cm−1); this value is almost twice of that previously observed in the cases of HKUST-117 and CPO-27-Ni.18 On the low-frequency side of this main adsorption, we observe the growth of less-intense bands, centered around 2268 cm−1 for both phases, corresponding to Cd2+· · ·O13CO, which is present naturally in 12CO2 (1%). In the low-frequency range, an intense band is expected for the doubly degenerate bending mode (ν2) of CO2 (668 cm−1), and a singlet at 658 cm−1 (Figure 5) is observed for both phases. In the high-frequency region (3800−3500 cm−1), two peaks are observed at 3690 and 3580 cm−1 (Figure 5). The nature of these two absorptions is well-known and is interpreted as the combination of ν1 and ν2 modes of CO2, similar to the case for compounds reported previously.17,18 In conclusion, two polymorphic PCPs constructed from Cd2+ and BTB ligand having interpenetrated 2D (6,3) net topology and 3D (10,3)-b net topology structures were synthesized. The structural dimensionalities of these two phases are dictated entirely by the number of single layers interpenetrated. These two interesting polymorphic PCPs selectively adsorb CO2 over N2, C2H4, and C2H6. Moreover, FT-IR spectroscopy of CO2 adsorbed on these two PCPs indicated that CO2 strongly interacts with OMSs present on Cd2+ ions. This study provides

Figure 4. Adsorption isotherms of phases 1 (top) and 2 (bottom) for several gas molecules. The sorption measurements were carried out for CO2 (red), C2H4 (brown), and C2H6 (blue) at 195 K and N2 (black) at 77 K. Filled and open symbols are adsorption and desorption data, respectively.

adsorb N2 at 77 K, probably owing to a blocking effect at such low temperatures. The CO2 adsorption at 195 K was 28 and 25 mL(STP)g−1 for 1 and 2, respectively. Up to date, MOF-21013 and MOF-20013 PCPs shown highest CO2 adsorption of about 74 wt % at 298 K and 50 bar pressure and Mg-MOF-7414 shown around 27 wt % CO2 adsorption at 298 K and 1 bar pressure. The adsorption measurements for C2H6 and C2H4 at 195 K on 1 and 2 phases indicate that the compounds cannot uptake these two gases owing to the large kinetic diameter (CO2: 3.3 Å, C2H6 and C2H4: 3.9 Å) (Figure 4). From the above adsorption measurements, we conclude that both phases 1 and 2 can selectively uptake CO2 from C2H6 and C2H4 at 195 K (Figure 4). The study15−18 of PCPs with OMSs and adsorptive gas molecules is a promising avenue for achieving strong framework−gas interactions and of particular interest in terms of specific interactions for the separation and activation of gas molecules in the field of porous materials. Phases 1 and 2 could possesses OMSs after the removal of solvent (DMF or MeOH) as suggested by the selective adsorption of CO2 molecules. To 983



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−X.; Tian, X. −Z. Cryst. Growth Des. 2012, 12, 3392. (c) Park, I.-H.; Kim, K.; Lee, S. S.; Vittal, J. J. Cryst. Growth Des. 2012, 12, 3397. (7) Synthesis of 1 ⊃ solvent: A solid mixture of H3BTB (11 mg, 0.025 mmol) and Cd(NO3)2·4H2O (7.7 mg, 0.025 mmol) was dissolved in a mixture of DMF/MeOH (0.5/0. 5 mL) in an 2 mL glass vial. To this reaction mixture, a few drops of concd HNO3 was added and the initial pH = 2.0. The whole reaction mixture was heated in a temperature controllable oven from room temperature to 100 °C, over a period of 4 h and then at 100 °C for 48 h. The oven was cooled from 100 to 30 °C over a period of 6 h. The product contains homogeneous colorless flake-type crystals, which were isolated by washing with MeOH and dried in air. Yield: 15.8 mg, 80% based on 1 mol of H 3 BTB. Elemental microanalysis for [Cd 2 (HBTB) 2 (DMF) (MeOH)]·(DMF)4(MeOH)(DMA) ≡ C73H82N6O19Cd2, calcd (%): C, 55.76; H, 5.26; N, 5.35. Found (%): C, 56.95; H, 5.43; N, 5.21. FTIR (4000−525 cm−1): 3417 (br, w), 3015 (s, w), 2760 (s, w), 1655(m), 1641 (s), 1577 (vs), 1523 (s), 1419 (w), 1370 (vs), 1243 (m), 1178 (m), 1094 (m), 1013 (m), 852 (s), 793 (m), 782 (vs), 705 (m), 668 (vs). (8) Synthesis of 2 ⊃ solvent: A solid mixture of H3BTB (11 mg, 0.025 mmol) and Cd(NO3)2·4H2O (7.7 mg, 0.025 mmol) was dissolved in a mixture of DMF/MeOH/H2O (0.5/0.25/0.25 mL) in an 2 mL glass vial. To the reaction mixture, 20 μL of NaOH (0.01 M) was added as a deprotonating agent and the initial pH = 6.0. The whole reaction mixture was heated in a temperature controllable oven from room temperature to 100 °C, over a period of 4 h and then at 100 °C for 48 h. The oven was cooled from 100 to 30 °C over a period of 6 h. The product contains homogeneous colorless flake-type crystals, which were isolated by washing with MeOH and dried in air. Yield: 16 mg, 83% based on 1 mol of H3BTB. Elemental microanalysis for [Cd(HBTB)(DMF)]·(DMF)2 ≡ C36H37N3O9Cd, calcd (%): C, 56.29; H, 4.86; N, 5.47. Found (%): C, 56.13; H, 4.95; N, 5.24. FT-IR (4000−525 cm−1): 3402 (br, w), 3020 (s, w), 2777 (s, w), 1656(m), 1641 (s), 1576 (vs), 1526 (s), 1467 (w), 1416 (w), 1368 (vs), 1246 (m), 1179 (m), 1095 (m), 1013 (m), 1011 (m), 874 (w), 853 (s), 811 (m), 782 (v), 705 (m), 668 (s). (9) Single crystal X-ray data for 1 ⊃ solvent: C73H82N6O19Cd2, fw = 1572.25, monoclinic, P21/n, a = 17.357(6), b = 26.425(8), c = 17.821(6) Å, β = 116.889(6)°, V = 7290(4) Å3, Z = 4, ρcalc = 1.433 gcm−3, μ = 0.658 mm−1, GOF = 1.055, R1 = 0.0794, and wR2 = 0.2188 for 9788 reflections with I > 2σ(I). (10) Single crystal X-ray data for 2 ⊃ solvent: C36H37N3O9Cd, fw = 768.09, monoclinic, P21/n, a = 14.915(4), b = 8.986(2), c = 26.759(7) Å, β = 96.272(3)°, V = 3565(2) Å3, Z = 4, ρcalc = 1.431 gcm−3, μ = 0.670 mm−1, GOF = 1.103, R1 = 0.0609, and wR2 = 0.1530 for 8466 of reflections with I > 2σ(I). (11) (a) Jin, Y.; Yoon, I.; Seo, J.; Lee, J.-E.; Moon, S. -T.; Kim, J.; Han, S. W.; Park, K. −M.; Lindoy, L. F.; Lee, S. S. Dalton Trans. 2005, 788. (b) Notash, B.; Safari, N.; Abedi, A.; Amani, V.; Khavasi, H. A. J. Coord. Chem. 2012, 62, 1638. (12) Batten, S. R; Robson, R. Angew. Chem., Int. Ed. 1998, 37, 1460. (13) Furukawa, H.; Ko, N.; Go, Y. B.; Aratani, N.; Choi, S. B.; Choi, E.; Yazaydin, A. O.; Snurr, R. Q.; O’Keefe, M.; Kim, J.; Yaghi, O. M. Science 2010, 329, 424. (14) (a) Bao, Z.; Yu, L.; Ren, Q.; Lu, X.; Deng, S. J. Colloid Interface Sci. 2011, 353, 549. (b) Yazaydin, A. Ö .; Snurr, R. Q.; Park, T.-H.; Koh, K.; Liu, J.; LeVan, M. D.; Benin, A. I.; Jakubczak, P.; Lanuza, M.; Galloway, D. B.; Low, J. L.; Willis, R. R. J. Am. Chem. Soc. 2009, 131, 18198. (15) Sumida, K.; Rogow, D. L.; Mason, J. A.; McDonald, T. M.; Bloch, E. D.; Herm, Z. R.; Bae, T.-H.; Long, J. R. Chem. Rev. 2012, 112, 724. (16) Serre, C.; Bourrelly, S.; Vimont, A.; Ramsahye, N. A.; Maurin, G.; Llewellyn, P. L.; Daturi, M.; Filinchuk, Y.; Leynaud, O.; Barnes, P.; Férey, G. Adv. Mater. 2007, 19, 2246. (17) Bordiga, S.; Regli, L.; Bonino, F.; Groppo, E.; Lamberti, C.; Xiao, B.; Wheatley, P. S.; Morris, R. E.; Zecchina, A. Phys. Chem. Chem. Phys. 2007, 9, 2676.

a roadmap for the design and synthesis of novel porous materials of different dimensionalities with OMSs.

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ASSOCIATED CONTENT

S Supporting Information *

Additional experimental methods, ORTEP diagrams, X-ray diffraction patterns, TGA diagrams, FTIR spectra, and X-ray crystallographic information files (CIF) for 1 ⊃ solvent and 2 ⊃ solvent. This material is available free of charge via the Internet at http://pubs.acs.org.

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AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS The ENOES Hydrogen Fund Trust financially supported this work. REFERENCES

(1) (a) Férey, G.; Mellot-Draznieks, C.; Serre, C.; Millange, F. Acc. Chem. Res. 2005, 38, 217. (b) Yaghi, O. M.; O’Keeffe, M.; Ockwig, N. W.; Chae, H. K.; Eddaoudi, M.; Kim, J. Nature 2003, 423, 705. (c) Das, S.; Kim, H.; Kim, K. J. Am. Chem. Soc. 2009, 131, 3814. (d) Tanabe, K. K.; Cohen, S. M. Chem. Soc. Rev. 2011, 40, 498. (e) Stock, N.; Biswas, S. Chem. Rev. 2012, 112, 933. (f) Kitagawa, S.; Kitaura, R.; Noro, S. Angew. Chem., Int. Ed. 2004, 43, 2334. (g) Tan, J. C; Cheetham, A. K. Chem. Soc. Rev. 2011, 40, 1059. (2) (a) Chui, S. S.-Y.; Lo, S. M.-F.; Charmant, J. P. H.; Orpen, A. G.; Williams, I. D. Science 1999, 283, 1148. (b) Bloch, E. D.; Queen, W. L.; Krishna, R.; Zadrozny, J. M.; Brown, C. M.; Long, J. R. Science 2012, 335, 1606. (c) Ohmori, O.; Fujita, M. Chem. Commun. 2004, 1586. (d) Han, J. W.; Hill, C. L. J. Am. Chem. Soc. 2007, 129, 15094. (e) Horike, S.; Dincă, M.; Tamaki, K.; Long, J. R. J. Am. Chem. Soc. 2008, 130, 5854. (f) Dincă, M.; Long, J. R. Angew. Chem., Int. Ed. 2008, 47, 6766. (g) Xiang, S.; Zhou, W.; Gallegos, J. M.; Liu, Y.; Chen, B. J. Am. Chem. Soc. 2009, 131, 12415. (h) Chen, B.; Ockwig, N. W.; Millward, A. R.; Contreras, D. S.; Yaghi, O. M. Angew. Chem., Int. Ed. 2005, 44, 4745. (i) Meng, L.; Cheng, Q.; Kim, C.; Gao, W.-Y.; Wojtas, L.; Chen, Y.-S.; Zaworotko, M. J.; Zhang, X. P.; Ma, S. Angew. Chem., Int. Ed. 2012, 51, 10082. (j) Horike, S.; Dincă, M.; Tamaki, K.; Long, J. R. J. Am. Chem. Soc. 2008, 130, 5854. (k) Wang, X.-S.; Meng, L.; Cheng, Qigan.; Kim, C.; Wojtas, L.; Chrzanowski, M.; Chen, Y.-S.; Zhang, X. P.; Ma, S. J. Am. Chem. Soc. 2011, 133, 16322. (l) Kitaura, R.; Onoyama, G.; Sakamoto, H.; Matsuda, R.; Noro, S-i.; Kitagawa, S. Angew. Chem., Int. Ed. 2004, 43, 2684. (m) Ma, S.; Zhou, H.-C. J. Am. Chem. Soc. 2006, 128, 11734. (3) Chae, H. K.; Siberio-Pérez, D. Y.; Kim, J.; Go, Y. B; Eddaoudi, M.; Matzger, A. J.; O’Keeffe, M.; Yaghi, O. M. Nature 2004, 427, 523. (4) (a) Devic, T.; Serre, C.; Audebrand, N.; Marrot, J.; Férey, G. J. Am. Chem. Soc. 2005, 127, 12788. (b) Hausdorf, S.; Baitalow, F.; Bohle, T.; Rafaja, D.; Mertens, F. O. R. L. J. Am. Chem. Soc. 2010, 132, 10978. (c) Sumida, K.; Hill, M. R.; Horike, S.; Dailly, A.; Long, J. R. J. Am. Chem. Soc. 2009, 131, 15120. (d) Volkringer, C.; Loiseau, T.; Marrot, J.; Férey, G. CrystEngComm 2009, 11, 58. (f) Foo, M. L.; Horike, S.; Kitagawa, S. Inorg. Chem. 2011, 50, 11853. (5) (a) Dang, D.; Wu, P.; He, C.; Xie, Z.; Duan, C. J. Am. Chem. Soc. 2010, 132, 14321. Xiang, H.; Gao, W.-Y.; Zhong, D.-C.; Jiang, L.; Lu, T.-B. CrystEngComm 2011, 13, 5825. (b) Mu, B.; Huang, Y.; Walton, K. S. CrystEngComm 2010, 12, 2347. (c) Lin, Q.; Wu, T.; Bu, X.; Feng, P. Dalton Trans. 2012, 41, 3620. (6) (a) Ma, L.; Lin, W. Angew. Chem., Int. Ed. 2009, 48, 3637. (b) Luo, F.; Yuan, Z. -Z.; Feng, X. -F.; Battenaaa, S. R.; Li, J. -Q.; Luo, M. -B; Liu, S. −J.; Xu, W. −Y.; Sun, G. −M.; Song, Y. −M.; Huang, H. 984



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(18) Dietzel, P. D. C.; Johnsen, R. E.; Fjellva, H.; Bordiga, S.; Groppo, Elena.; Chavanc, S.; Blom, R. Chem. Commun. 2008, 5125.

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and BTB-based Porous Coordination Polymers with Open Metal Sites

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