DNA interaction, enhanced DNA photocleavage, electrochemistry, thermal investigation and biopotencial properties of new mixed-ligand complexes of Cu(II)/VO(IV) based on Schiff bases

Using the Schiff base ligand, dbdppo (4-(3′,4′-dimethoxybenzaldehydene)2-3-dimethyl-1-phenyl-3-pyrazolin-5-one or hnbdppo (4-(3′-hydroxy-4′-nitrobenzaldehydene)2-3-dimethyl-1-phenyl-3-pyrazolin-5-one with polypyridyl ligand(s) as co-ligand(s), Cu(II) and VO(IV) complexes have been synthesized and characterized by the physicochemical properties. The electrochemical properties, DNA binding affinities, as well as photonuclease activities of the complexes, were examined in detail. The DNA binding characteristics of the Cu(II) and VO(IV) complexes was investigated by spectroscopic, electrochemical and viscosity measurements. The UV–Vis, and magnetic moment data revealed an octahedral geometry around Cu(II) ion and square-pyramidal geometry around VO(IV) ion and conductivity data conveyed the electrolytic nature of the complexes. The spectroscopic studies together with cyclic voltammetry and viscosity experiments support that both of the complexes bound to CT DNA by partial intercalation into the base pairs of DNA. Moreover, these complexes have been found to promote the photocleavage of plasmid DNA pBR322 under irradiation at 365 nm. Further, the synthesized ligands, in comparison to their metal complexes were screened for their antimicrobial activity against bacterial and fungal species. The activity data show that the metal complexes have more antimicrobial potent than the parent Schiff base ligands.