Iron(III) complexes derived from azo-containing salicylaldoxime ligands: Synthesis, structures and biological evaluations

Abstract

Two novel mononuclear Fe(III) complexes derived from azo-containing salicylaldoxime ligands were synthesized and characterized by elemental analyses, spectroscopic data i.e. IR, 1H NMR, UV-Vis, electrospray ionization mass spectra, molar conductivity, and magnetic susceptibility measurements. Both the experimental and theoretical results strongly suggest that the ligands have a major contribution to the azo enol imine form instead of the hydrazo keto imine and azo keto amine forms in solution/solid-state. The electronic spectra of the ligands and their iron(III) complexes were calculated theoretically for the band assignments by using DFT and TD-DFT/CPCM methods. DNA binding, cleavage, and antioxidative activities of the investigated compounds were studied. It has been shown that the ligands and their iron (III) complexes tested bind to DNA via the intercalative mode. It was observed that all molecules tested inhibited topoisomerase I almost to the same degree. One of the most striking results among the antioxidant activity tests is that the hydroxyl radical scavenging activities of the ligands and complexes are higher than the standard antioxidant mannitol.