Three highly stable, hexacoordinated nonoxidovanadium(IV), V(IV)(L)2, complexes (1-3) have been isolated and structurally characterized with tridentate aroylhydrazonates containing ONO donor atoms. All the complexes are stable in the open air in the solid state as well as in solution, a phenomenon rarely observed in nonoxidovanadium(IV) complexes. The complexes have good solubility in organic solvents, permitting electrochemical and various spectroscopic investigations. The existence of nonoxidovanadium(IV) complexes was confirmed by elemental analysis, ESI mass spectroscopy, cyclic voltammetry, EPR, and magnetic susceptibility measurements. X-ray crystallography showed the N3O3 donor set to define a trigonal prismatic geometry in each case. All the complexes show in vitro insulin mimetic activity against insulin responsive L6 myoblast cells, with complex 3 being the most potent, which is comparable to insulin at the complex concentration of 4 μM, while the others have moderate insulin mimetic activity. In addition, the in vitro antiproliferative activity of complexes 1-3 against the HeLa cell line was assayed. The cytotoxicity of the complexes is affected by the various functional groups attached to the bezoylhydrazone derivative and 2 showed considerable antiproliferative activity compared to the most commonly used chemotherapeutic drugs.

Eight alkali metal ion-mediated dioxidovanadium(v), [{V(V)O2L(1-6)}A(H2O)n]∝, complexes for A = Li(+), Na(+), K(+) and Cs(+), containing tridentate aroylhydrazonate ligands coordinating via ONO donor atoms, are described. All the synthesised ligands and the metal complexes were successfully characterised by elemental analysis, IR, UV-Vis and NMR spectroscopy. X-ray crystallographic investigation of 3, 5-7 shows the presence of distorted NO4 coordination geometries for LVO2(-) in each case, and varying μ-oxido and/or μ-aqua bridging with interesting variations correlated with the size of the alkali metal ions: with small Li(+), no bridging-O is found but four ion aggregates are found with Na(+), chains for K(+) and finally, layers for Cs(+). Two (5) or three-dimensional (3, 6 and 7) architectures are consolidated by hydrogen bonding. The dioxidovanadium(v) complexes were found to exhibit DNA binding activity due to their interaction with CT-DNA by the groove binding mode, with binding constants ranging from 10(3) to 10(4) M(-1). Complexes 1-8 were also tested for DNA nuclease activity against pUC19 plasmid DNA which showed that 6 and 7 had the best DNA binding and photonuclease activity; these results support their good protein binding and cleavage activity with binding constants ranging from 10(4) to 10(5) M(-1). Finally, the in vitro antiproliferative activity of all complexes was assayed against the HeLa cell line. Some of the complexes (2, 5, 6 and 7) show considerable activity compared to commonly used chemotherapeutic drugs. The variation in cytotoxicity of the complexes is influenced by the various functional groups attached to the aroylhydrazone derivative.

) respectively, which signifies the potential of these oxidovanadium(V) complexes to stimulate research for the synthesis of a better catalyst.

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The interaction of four neutral oxidovanadium(v) complexes with DNA and their cytotoxic activities have been reported.