CH3‑Tagged Bis(pyrazolato)-Based Coordination Polymers and Metal–Organic Frameworks: An Experimental and Theoretical Insight

• Published in: Crystal growth & design Vol. 17; no. 7; pp. 3854 - 3867
• Main Authors: Mosca, Nello, Vismara, Rebecca, Fernandes, José A, Casassa, Silvia, Domasevitch, Konstantin V, Bailón-García, Esther, Maldonado-Hódar, Francisco J, Pettinari, Claudio, Galli, Simona
• Format: Journal Article
• Language: English
• Published: American Chemical Society 05-07-2017
• ISSN: 1528-7483; 1528-7505
• DOI: 10.1021/acs.cgd.7b00471

The novel coordination polymers M­(Me2BPZ) (M = Co, Zn; H2Me2BPZ = 3,3′-dimethyl-1H,1′H-4,4′-bipyrazole), M­(H2Me2BPZ)­(CH3COO)2­(H2O)2 (M = Co, Ni), and Cu­(H2Me2BPZ)­(Cl)2 were isolated along conventional or solvothermal routes. Their crystal structure was unveiled by powder X-ray diffraction (PXRD), while their thermal stability was assessed by coupling thermogravimetric analysis to variable-temperature PXRD. The textural properties of the M­(Me2BPZ) (M = Co, Zn) compounds, featuring three-dimensional open frameworks with one-dimensional channels, were assessed by N2 and CO2 adsorption at 77 and 273 K, respectively, and compared to those of the nonmethylated isostructural counterparts M­(BPZ) (M = Co, Zn; H2BPZ = 1H,1′H-4,4′-bipyrazole). The positive effect of the methyl groups in CO2 adsorption, suggested by the adsorption energy trend [E ads(M­(Me2BPZ)) > E ads(M­(BPZ))] and substantiated by theoretical calculations at the B3LYP-D3 level coupled to topological analyses, is counterbalanced by the higher steric hindrance of Me2BPZ2– vs BPZ2–, finally reducing the amount of gas adsorbed by the M­(Me2BPZ) couple vs the M­(BPZ) one.