Hydrothermal Synthesis, Crystal Structures, and Catalytic Properties of Three Coordination Polymers Containing ­Flexible Bis(benzimidazole) and Dicarboxylate Ligands†

Three metal-organic coordination polymers, namely {[Cd(L1)(1,2-chdc)]·2H2O}n (1), {[Ni(L2)(1,2-chdc)]·H2O}n (2), and [Cd(L2)(npht)]n (3) [L1 = 1,2-bis(2-methylbenzimidazol-1-ylmethyl)benzene, L2 = 1,2-bis(5,6-dimethylbenzimidazol-1-ylmethyl)benzene, 1,2-H2chdc = 1,2-cyclohexanedicarboxylic acid, H2npht = 3-nitrophthalic acid] were synthesized under hydrothermal conditions and structurally characterized by single-crystal X-ray diffraction methods, IR spectroscopy, TGA, and elemental analysis. In compound 1, two 1,2-chdc2– ligands connect two neighboring Cd atoms to form a dinuclear [Cd2(1,2-chdc)2] subunit, which is further linked by L1 ligands to construct a 1D ladder-like chain. Compound 2 exhibits a 2D (4,4) coordination network with {44.62} topology, whilst compound 3 shows a 1D helical chain structure. The fluorescence, UV/Vis diffuse reflection spectra, and catalytic properties of complexes 1–3 for the degradation of the congo red azo dye in a Fenton-like process are investigated.