Syntheses, Structures and Photoluminescence of Three Cd(II) Coordination Polymers Based on Flexible Bis(Benzimidazole) and Dicarboxylate Ligands

Abstract

Three new Cd(II) coordination polymers constructed from two structurally related ligands, 1,1′-(1,3-propane)bis-(2-methylbenzimidazole) (pbmb) and 1,1′-(1,4-butanediyl)bis(2-methyl-benzimidazole) (bbmi), have been hydrothermally synthesized: [Cd(pbmb)(hmph)] n (1), [Cd(pbmb)(chdc)] n (2) and [Cd(bbmi)0.5(chdc)] n (3), where H2hmph = homophthalic acid and H2chdc = 1,4-cyclohexanedicarboxylic acid. These complexes were structurally characterized by elemental analysis, IR, and single crystal X-ray diffraction analyses. Complex 1 possesses a two-dimensional 63 honeycombed network structure, which are further extended into a 3D supermolecule framework through weak C–H···O hydrogen bonding interactions. 2 displays an infinite 1D loop-like chain structure, which is further assembled into a 2D supramolecular layer via C–H···O hydrogen bonding interactions. In complex 3, CdII ions are connected by chdc2− anions to form a 1D chain containing binuclear clusters, which is further connected by the bbmi exhibiting a 2D (3,4)-connected network with a point symbol of {42·63·8}{42·6}. The thermal and photoluminescence properties of the three complexes were investigated in detail. Three Cd(II) coordination polymers constructed by flexible bis-(2-methylbenzimidazole) and dicarboxylate anions co-ligands. These compounds display diverse architectures from 1D to 2D. The various structures indicate that flexible dicarboxylate anions have a remarkable effect on the final structures and topologies.