Syntheses, crystal structures, DNA binding, DNA cleavage and DFT study of Co(iii) complexes involving azo-appended Schiff base ligands

Abstract

Herein, we have reported three new Co(III) complexes involving azo-appended Schiff base ligands. All three complexes were characterized using different spectroscopic tools like NMR, FTIR and UV-Vis. The structures of the complexes 1–3, were confirmed by single crystal X-ray diffraction analysis. DFT and TDFFT computations were performed to support the structural and electronic parameters of the complexes. Computed bond distances and angles well resemble those of X-ray data. Absorption and viscometric titration studies revealed that each of these octahedral complexes interacts with CT DNA to result in minor groove binding. The intrinsic binding constants (K_b) were calculated to be 7.90 × 10⁵, 1.35 × 10⁵ and 1.075 × 10⁵ M⁻¹, respectively, for complexes 1–3. Complexes 1–3 also exhibited oxidative DNA cleavage activity in the presence of hydrogen peroxide.