Self-assembly of Two Cobalt(II) Coordination Polymers Derived from Tetrabromoterephthalate and Flexible Bis(Benzimidazole) Co-ligands†

Two new cobalt(II) coordination polymers, {[Co(L1)(tbta)]0.8H(2)O}(n) (1) and {[Co(L2)(tbta)]H2O}(n) (2) [L1 = 1,1-(1,3-propanediyl)bis(2-methylbenzimidazole), L2 = 1,2-bis(2-methylbenzimidazole-1-ylmethyl)benzene, H(2)tbta = tetrabromoterephthalic acid] were obtained under hydrothermal conditions and structurally characterized by single-crystal X-ray diffraction methods, IR spectroscopy, TGA, and elemental analysis. The cobalt atoms present similar environments with tetrahedral arrangements in 1 and 2. The two complexes show a 2D (4,4) coordination network with sql topology. Compound 2 is further extended into a rare 3,3,4T3 three-dimensional supramolecular framework by weak C-HO 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 were investigated.