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)]center dot 2H(2)O}(n) (1), {[Ni(L2)(1,2-chdc)]center dot 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-H(2)chdc = 1,2-cyclohexanedicarboxylic acid, H(2)npht = 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-chdc(2-) ligands connect two neighboring Cd atoms to form a dinuclear [Cd-2(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 {4(4).6(2)} 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.