Weak interactions in imidazole‐containing zinc( II )‐based metal–organic frameworks

The self‐assembly of the two zinc(II) metal–organic frameworks, [Zn 2 (L)(bdc) 2 ]·3MeOH·4H 2 O} n ( 1 , L = 2‐(pyridin‐4‐yl)‐3H‐imidazo[4,5‐c]pyridine, H 2 bdc = 1,4‐benzenedicarboxylic acid) and [Zn 2 (L)(bdc) 2 ]·2DMF·H 2 O} n ( 2 ), was achieved under mild reaction conditions. Both compounds 1 and 2 were structurally characterized by single‐crystal X‐ray diffraction analysis. Interestingly, the coordination modes of the ligand L in two structures are entirely different. Compounds 1 and 2 were made up of paddle wheel‐shaped {Zn 2 (O 2 C) 4 } secondary building unit (SBU) clusters, which adopted three‐dimensional structures with a pcu topology. Rich weak interactions were observed in the structures of both 1 and 2 . The uncoordinated imidazole and pyridine moieties exhibited electron donor–acceptor interactions, π–π stacking, hydrogen bonding, and CH–π interactions. These interactions also facilitated the abilities of the framework to adsorb CO 2 molecules. Gas adsorption studies revealed that compound 1 selectively adsorbed CO 2 (131.1 cm 3 /g) over N 2 (23.5 cm 3 /g) and H 2 (36.5 cm 3 /g) at a pressure of 1 atm.