4,4′-Bipyridine-aided synthesis and characterization of Zn(II) and Cd(II) 2-sulfoterephthalate complexes

• Complexes 1–3 possess helices with different chirality arranging alternately.
• The structural diversity can be attributed to various coordination modes of ligands.
• The formation of helical structure is related to the adjacent carboxyl and sulfonate groups.
• Bpy exhibits three roles: bridge, hydrogen bonding acceptor, and template.

Six d10 complexes, [Zn1.5(stp)(bpy)0.5(H2O)2]·0.5H2O (1), Cd1.5(stp)(bpy)0.5(H2O)2 (2), [Cd1.5(stp)(bpy)(H2O)]·H2O (3), [Zn0.5(bpy)0.5(H2O)2][Zn(stp)(bpy)(H2O)]·0.5H2O (4), Cd3(stp)2(bpy)3(H2O)3 (5), Hbpy·[Zn0.5(bpy)(H2O)2][Zn0.5(stp)(H2O)]·H2O (6) based on 2-sulfoterephthalate (stp3−) and 4,4′-bipyridine (bpy) have been synthesized under hydro/solvo-thermal conditions and structurally characterized. Complex 1 exhibits a three-fold interpenetrated 3D porous architecture. Complexes 2 and 3 possess helices with different chirality arranging alternately. 4 and 6 are addition compounds, which compose of complex cation and complex anion. Complex 5 features a 3D layer-pillar framework in which a (4, 4) grid layer is constructed by stp3− ligands and Cd(II) ions, and the layers are further connected by bpy pillars. The solid-state luminescent properties of the coordination polymers have also been investigated.

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