Synthesis and characterization of a new series of unsymmetrical macrocyclic binuclear vanadyl(IV) complexes: Electrochemical, antimicrobial, DNA binding and cleavage studies

A new series of unsymmetrical macrocyclic binuclear bis-phenoxo bridged oxidovanadium(IV) complexes have been synthesized and characterized by elemental and spectral techniques. A cyclic voltammetric investigation of these binuclear VIVO complexes evidenced that two successive quasi-reversible one electron transfer reduction waves (E1pc = −0.54 to −0.67 V, E2pc = −0.80 to −0.85 V) are obtained. In the positive potential region (+0.50 to +1.00 V) two quasi-reversible oxidation couples are observed for all the complexes. The first one electron oxidation is observed around (E1pc) +0.63 to +0.78 V and the second around (E2pc) +0.82 to +0.97 V. The ESR spectra of all the binuclear VIVO complexes showed a single broad-band resonance at ca. g = 1.97–2.11 with the half field signal at 1500G (M = ±2), which suggest magnetic interactions between two VIVO ions through the phenolate bridge. DNA binding experiments show that the aromatic diimine containing macrocyclic VIVO complexes display better DNA interactions than the aliphatic diimine containing VIVO analogues. These complexes significantly promote the oxidative cleavage of supercoiled plasmid DNA under physiological conditions in the presence of H2O2. All the complexes show noticeable growth inhibition of some plant pathogenic fungal species and human pathogenic bacterial species.

A series of unsymmetrical macrocyclic binuclear bis-phenoxo bridged oxidovanadium(IV) complexes have been synthesized and characterized by elemental and spectral techniques. A cyclic voltammetric investigation of these complexes evidenced that two successive quasi-reversible one electron transfer reduction waves in the negative and positive potential regions, E1pc = −0.54 to −0.67 V, E2pc = −0.80 to −0.85 V and E1pc = +0.63 to +0.78 V, E2pc = +0.82 to +0.97 V, respectively, are obtained. The aromatic diimine containing macrocyclic VIVO complexes display better DNA interactions than the aliphatic diimine containing VIVO analogues. These complexes significantly promote the oxidative cleavage of supercoiled plasmid DNA in the presence of H2O2. All the complexes display noticeable antifungal and antibacterial activities.Figure optionsDownload as PowerPoint slide