Mononuclear and binuclear complexes derived from hydrazone Schiff base NON donor ligand: Synthesis, structure, theoretical and biological studies

Abstract

Two new binuclear Cu(II) and Co(II) and mononuclear Ni(II) complexes of the flexible hydrazone Schiff base, (E)-N′-(1-(2-aminophenyl) ethylidene)-2-oxo-2-(phenylamino) acetohydrazide (H2AAH) have been synthesized and characterized by conventional techniques. In Co(II) and Cu(II) complexes, H2AAH acts as mononegative N3O2 pentadentate and in Ni(II) complex as N2O tridentate. An octahedral geometry for Ni(II) and Co(II) complexes and a tetrahedral structure for Cu(II) complex have been proposed. The geometry of Co(II) complex was further confirmed by X-ray powder diffraction technique. Ea, ΔS∗, ΔH∗ and ΔG∗ parameters were evaluated for thermal decomposition stages of the hydrazone and its complexes using Coats-Redfern and Horowitz-Metzger methods. The antimicrobial activity of all compounds against Staphylococcus aures, Escherichia coli as bacterial cultures and Candida albicans and Aspergillus flavus as fungal cultures were investigated. Also, the antioxidant activity using ABTS+ free radical assay, in vitro anticancer against human breast mammary gland cell line as well as DNA interaction studies were studied. The antibacterial assay revealed the high antibacterial activity for Co(II) and Ni(II) complexes and selective antifungal activity for all complexes. On the other hand, H2AAH showed the potent antioxidant and anticancer activities comparable to the metal complexes and the standard drugs.Finally, it is observed that various concentrations of H2AAH complexed with lambda DNA while high concentrations of Cu(II) complex degraded DNA completely.