Solvent or Temperature Induced Diverse Coordination Polymers of Silver(I) Sulfate and Bipyrazole Systems: Syntheses, Crystal Structures, Luminescence, and Sorption Properties

Three new coordination polymers, [Ag4(H2bpz)4(SO4)2]·H2O (1), [Ag2(H2bpz)2(SO4)]·3H2O (2), and [Ag3(H2bpz)4]­(SO4)2/3(OH)5/3·4H2O (3) have been solvothermally synthesized with Ag2SO4 and flexible ligand 3,3′,5,5′-tetramethyl-4,4′-bipyrazole (H2bpz) in different solvents and temperatures. Complex 1 is a 2-fold interpenetrated three-dimensional (3D) framework with an uncommon (3,5)-connected hms topology. Complex 2 is a structural isomer of 1 and shows a three-connected 2D ths net consisting of interesting 3-fold and 2-fold heterochiral helical chains. Complex 3 discloses a grid layer structure, containing heterochiral helical chains and an unusual meso-helix. More interestingly, three sets of layers in 3 stack in different directions, affording an unprecedented 2D + 2D + 2D → 3D polycatenating cationic framework with 1D + 3D porous systems. In 1–3, H2bpz exhibit exobidentate bridging fashions with wide-ranged interpyrazole tilting angles and changeable coordination configurations, such as cis and trans fashions in 1 and 3 and uniform trans fashion in 2. These lead to the isomeric [Ag­(H2bpz)]n arrays of wavelike and helical chains in 1 and 2, respectively. Complexes 1–3 display solid-state photoluminescence stemming from the ligand-centered fluorescent emissions of H2bpz. Because of the highly polar framework, 3 shows excellent adsorption selectivity for CO2 over N2.