Syntheses, crystal structures, DNA binding and electrochemical properties of two mixed-ligand cobalt(II) coordination polymers constructed from 5-(carboxymethoxy)isophthalic acid and bis-benzimidazole ligands

Two new cobalt(II) coordination polymers, [Co(HL)(bbe)] (n) (1) and [Co(HL)(bbop)] (n) (2) (H3L = 5-(carboxymethoxy)isophthalic acid, bbe = 1,2-bis(benzimidazol-2-yl)ethane, bbop = 1,3-bis(benzimidazol-2-yl)-2-oxapropane), were synthesized and characterized by elemental analyses, IR spectra, single-crystal X-ray diffraction and thermogravimetric analyses. Both complexes exhibit 1D chain structures, constructed from HL2- anions bridging metal ions. The 1D chains are further connected by hydrogen bonds and pi-pi stacking interactions to form the 3D supramolecular architectures. The cobalt centers display different coordination environments, with a tetrahedral geometry in 1 and a distorted tetragonal pyramid in 2. The DNA binding properties of both complexes were investigated by UV absorption spectroscopy. The electrochemical properties of both complexes were studied by cyclic voltammetry.