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 (<b>1</b>), [Ag₂(H₂bpz)₂(SO₄)]·3H₂O (<b>2</b>), and [Ag₃(H₂bpz)₄]­(SO₄)_2/3(OH)_5/3·4H₂O (<b>3</b>) have been solvothermally synthesized with Ag₂SO₄ and flexible ligand 3,3′,5,5′-tetramethyl-4,4′-bipyrazole (H₂bpz) in different solvents and temperatures. Complex <b>1</b> is a 2-fold interpenetrated three-dimensional (3D) framework with an uncommon (3,5)-connected hms topology. Complex <b>2</b> is a structural isomer of <b>1</b> and shows a three-connected 2D ths net consisting of interesting 3-fold and 2-fold heterochiral helical chains. Complex <b>3</b> discloses a grid layer structure, containing heterochiral helical chains and an unusual <i>meso-</i>helix. More interestingly, three sets of layers in <b>3</b> stack in different directions, affording an unprecedented 2D + 2D + 2D → 3D polycatenating cationic framework with 1D + 3D porous systems. In <b>1</b>–<b>3</b>, H₂bpz exhibit exobidentate bridging fashions with wide-ranged interpyrazole tilting angles and changeable coordination configurations, such as <i>cis</i> and <i>trans</i> fashions in <b>1</b> and <b>3</b> and uniform <i>trans</i> fashion in <b>2</b>. These lead to the isomeric [Ag­(H₂bpz)]_<i>n</i> arrays of wavelike and helical chains in <b>1</b> and <b>2</b>, respectively. Complexes <b>1</b>–<b>3</b> display solid-state photoluminescence stemming from the ligand-centered fluorescent emissions of H₂bpz. Because of the highly polar framework, <b>3</b> shows excellent adsorption selectivity for CO₂ over N<sub>2