Effect of substituent on structures and catalytic properties of cobalt(II) isophthalate coordination polymers with a semi-rigid bis(benzimidazole)

Three Co(II) coordination polymers based on flexible bis(2-dimethylbenzimidazole) and the derivatives of the familiar isophthalate co-ligands, namely [Co(L)(ip)](n) (1), [Co-2(L)(2)(nip)(2)](n) (2) and [Co-2(L)(2)(t-bip)(2)center dot 2H(2)O](n) (3) (L = 1,2-bis(2-methylbenzimidazol-1-ylmethyl)benzene, H(2)ip = isophthalic acid, H(2)nip = 5-nitroisophthalic acid, H(2)tbip = 5-tert-butylisophthalic acid) have been synthesized by hydrothermal methods and characterized by elemental analyses, IR spectra, thermogravimetric analyses and single-crystal X-ray diffraction. Both complexes 1 and 2 exhibit a 2-fold interpenetrating 3D network with 6(6)-dia topology, whereas complex 3 is bridged by the L and tbip(2-) ligands to form a rarely tri-nodal (3,3,5) layer with 3,3,5L18 topology. The results indicate that Co(II) mixed coordination polymers structurally modulated by the substituent effect of isophthalate-involved co-ligands. In addition, the fluorescence and catalytic activity of the complexes for the degradation of methyl orange by the sodium persulfate in a Fenton-like process have been investigated. (C) 2018 Elsevier B.V. All rights reserved.