Synthesis and structural characterization of oxovanadium(IV) complexes of dimedone derivatives

We have successfully synthesized new oxovanadium (IV) complexes with dimedone derivatives and their structure were confirmed by elemental analyses, spectroscopic techniques (FT-IR, UV–visible, EPR) and thermal analysis. The reaction of [VO (acac)₂] with the azo dimedone ligands ( HL _n ) produced mononuclear oxovanadium (IV) complexes with formula [VO (L_n)₂]H₂O. Results of the molar conductance proved that VO²⁺ complexes are non-electrolytes and fall in the range 14–16 Ω-¹cm²mol⁻¹. The coordination geometry of VO (IV) complexes is square-pyramidal, where vanadium (IV) ion is coordinated by oxygen atom of the carbonyl (C=O) group, and nitrogen atom of the deprotonating hydrazone moiety (–NH–), while the fifth position is occupied by an oxo group. Moreover, the optimized structure, bond angles, bond lengths, as well as the calculated quantum chemical parameters of the complexes have been estimated. DNA binding activities of the complexes were investigated using electronic absorption titration and viscosity measurements. The obtained results showed groove binding of the complexes to CT-DNA accompanied with a partial insertion of the ligand between the base stacks of the DNA with a binding constant of 2.07–5.51 x 10⁵ M⁻¹ range. Evaluation results of the synthesized complexes against the human cancer cell lines HepG-2 and MCF-7, as compared to the positive controls in the viability assay of vinblastine and colchicine have been reported. The in vitro anti-oxidant activity of all the complexes is determined by DPPH free radical-scavenging assay. Finally, the anti-microbial activities of the complexes have been investigated against fungal (Candida albicans), gram negative bacteria (Escherichia coli), and gram positive bacteria (Staphylococcus aureus) using the disc-diffusion method.