Synthesis, structure, and DNA binding/cleavage of two novel binuclear Co (II) complexes

In this study, two novel binuclear Co(II) complexes, [Co-4(L-1)(2)(CH3CH2O)(4)center dot 5.5H(2)O (1) and [Co-2(L-2)(2)(CH3COO) (H2O)]center dot 2CH(3)OH center dot 3H(2)O (2)], with the ligands H3L1 and H2L2 were synthesized and structurally characterized using single crystal X-ray diffraction. The crystal structures of complex 1 and 2 belong to a monoclinic system with space group of P2(1)/n and triclinic system with space group of P-1, respectively. Their interaction with CT-DNA was investigated using electron absorption and fluorescent spectroscopy. The apparent binding constants (K-app) of two complexes (1 and 2) were determined to be 534 x 10(5) and 5.82 x 10(5), respectively, and both exhibited a moderate intensity of insertion with 2 > 1. Fluorescence quenching studies indicated that the fluorescence quenching mechanism of complex 1 is dynamic quenching and that of complex 2 is a static quenching mechanism. The chemical nuclease activity of the complexes was studied using agarose gel electrophoresis. The results suggest that when H2O2 is added, complexes I and 2 exhibit chemical nuclease activity. The cleavage mechanisms between the complexes and plasmid DNA are the likely oxidative cleavage process of hydroxyl radical (center dot OH) and singlet oxygen (O-1(2)) as active species. (C) 2018 Elsevier B.V. All rights reserved.