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

摘要

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.