Four cobalt(II) coordination polymers with diverse topologies derived from flexible bis(benzimidazole) and aromatic dicarboxylic acids: syntheses, crystal structures and catalytic properties

Four mixed ligand coordination polymers based on the flexible bis(5,6-dimethybenzimidazole) and aromatic dicarboxylic acids, namely, [Co(L1)(bpdc)](n) (1), {[Co(L1)(npht)]center dot 0.5H(2)O}(n) (2), [Co(L2)(bpdc)](n) (3), and [Co(L3)(bpdc)(H2O)](n) (4) (L1 = 1,4-bis(5,6-dimethylbenzimidazol-1-ylmethyl)benzene, H(2)bpdc = 4,4'-biphenyldicarboxylic acid, L2 = 1,3-bis(5,6-dimethylbenzimidazol-1-ylmethyl)benzene, H(2)npht = 3-nitrophthalic acid, L3 = 1,1'-bis(5,6-dimethylbenzimidazole)methane) have been hydrothermally synthesized and structurally characterized. Polymer 1 features a 3D three-fold interpenetrating dia array with a 4-connected 6(6) network, while 2 exhibits a 3D noninterpenetrated 3-connected framework with a 10(3)-ThSi2 architecture. 3 and 4 have two-dimensional 3-connected (6(3)) and 4-connected (4(4)center dot 6(2)) topologies, respectively. Complex 4 ultimately is extended into an unusual 3D (3,5)-connected seh-3,5-P21/c supramolecular network via O-H center dot center dot center dot O hydrogen bonding interactions. The fluorescence and catalytic properties of the complexes for the degradation of the Congo red azo dye in a Fenton-like process are reported.