Coligand syntheses, crystal structures, luminescence and photocatalytic properties of five coordination polymers based on rigid tetracarboxylic acids and imidazole linkers

Abstract

Five coordination polymers (CPs) with distinct structures, namely, [Cu(H₂tptc)(1,4-bidb)]_n (1), {[Co₂(tptc)(1,3,5-tib)(H₂O)]·7H₂O}_n (2), {[Ni(tptc)_0.5(1,3-bimb)]·H₂O}_n (3), {[Zn(qptc)_0.5(1,4-bimb)]·3H₂O}_n (4), and {[Zn(qptc)_0.5(1,3-bimb)]·H₂O}_n (5) (H₄tptc = terphenyl-3,3′′,5,5′′-tetracarboxylic acid, H₄qptc = quaterphenyl-3,3′′′,5,5′′′-tetracarboxylic acid, 1,4-bidb = 1,4-bis(1-imidazol-yl)-2,5-dimethyl benzene, 1,3,5-tib = 1,3,5-tris(1-imidazol-yl)benzene, 1,3-bimb = 1,3-bis(imidazol-1-ylmethyl)benzene, and 1,4-bimb = 1,4-bis(imidazol-1-ylmethyl)benzene), have been synthesized through a mixed ligand strategy. Complex 1 features a new 3D (4,6)-connected net with a Schläfli symbol of (4²·6⁴)(4²·6⁸·7·8⁴). Complex 2 displays a 3D 2-fold interpenetrated framework with an unprecedented (3,3,4,4)-connected (6·8²)₂(6²·8³·10)(6²·8⁴) topology. Complex 3 exhibits a (3²·6²·7²)-kgm layer featuring a 2D + 2D → 3D packing supramolecular structure interweaved through [Ni(1,3-bimb)] lock knots. Complex 4 shows an unprecedented 3D (4,4)-connected 8⁶ net. Complex 5 is also a 2D + 2D → 3D supramolecular structure featuring kgm sheets hinged together through [Zn(1,3-bimb)] lock knots. In addition, the luminescence properties of 4 and 5 have been investigated. Moreover, complexes 1–3 show relatively good photocatalytic activities for methylene blue (MB) dye degradation in aqueous solution under UV light.