Mononuclear cobalt(III) and iron(II) complexes with diimine ligands: Synthesis, structure, DNA binding and cleavage activities, and oxidation of 2-aminophenol

Mononuclear cobalt(III) and iron(II) complexes with diimine ligands were synthesized and characterized by elemental analyses, spectroscopic and electrochemical techniques. Single crystal X-ray diffraction studies revealed that the metal ions in both complexes are situated in distorted octahedral environments comprised of six nitrogen atoms from three diimine ligands. Interaction of the complexes with calf thymus DNA was investigated through UV–Vis and fluorescence spectroscopic methods and viscosity measurements. These results suggest that both complexes preferably interact with CT-DNA through the grove binding mode. Moreover, both complexes are capable of promoting DNA cleavage in the presence of suitable activating agent(s). The nuclease activity is strongly suggested to be oxidative, possibly due to the involvement of a diffusible hydroxyl radical mechanism. Furthermore, the cobalt(III) complex has been found to be an excellent oxidant for oxidative coupling of 2-aminophenol to the phenoxazinone chromophore under aerobic conditions.

The syntheses and crystal structures of mononuclear cobalt(III) and iron(II) complexes derived from diimine ligands are reported. Both complexes interact with CT-DNA, preferably through a groove binding mode, and they are capable of promoting oxidative DNA cleavage in the presence of suitable activating agents. The cobalt(III) complex has been found to be an excellent oxidant for the oxidative coupling of 2-aminophenol to the phenoxazinone chromophore under aerobic conditions.Figure optionsDownload as PowerPoint slideHighlights
► Mononuclear cobalt(III) and iron(II) complexes with diimine ligands.
► Interaction of the complexes with CT-DNA through the grove binding mode.
► Oxidative DNA cleavage activity in the presence of suitable activating agents.
► Oxidation of 2-aminophenol by the cobalt(III) complex in the presence of molecular dioxygen.