Construction of 1D to 3D cadmium(II) coordination polymers from 4-(imidazol-1-yl)-benzoic acid: Effect of bridging anions

Three Cd(II) coordination polymers, [Cd(IBA)Cl(H2O)]n (1), [Cd(IBA)(CH3COO)]n (2) and [Cd(IBA)N3]n (3) derived from HIBA (HIBA = 4-(imidazol-1-yl)-benzoic acid), have been designed and prepared in the existence of different anions. 1 is a 1D chain and consists of Cd2Cl2 units bridged by imidazolyl nitrogen atom and chelating carboxylate of IBA. In 2, the adjacent Cd(II) are bridged by acetate to form a bis(carboxylate-O,O′)-Cd(II) dimeric unit, which is inter-connected by exo-tridentate IBA into a 2D layer, in which carboxylate of acetate and IBA alternatively bridge Cd(II) generating carboxylate-O,O′-Cd(II) chains. In 3, μ1,1-azide bridges Cd(II) forming a helical chain, which is further inter-connected by exo-tridentate IBA into a two-folded interpenetrated 3D network with unusual seh-3,5-P43212 topology. These results show significant anion-dependent effect on the formation of network structures. Solid-state photoluminescence investigation at room temperature indicates complexes 1–3 emit the intense photoluminescence around 450 nm.