Reactions of oxidobis(quinolin-8-olato)vanadium(IV) with hydroxamate ligands: A route providing mixed ligand and Quinolin-8-olato-Free Vanadium(IV) Complexes

Article abstract of DOI:10.1246/bcsj.20120066

Complexes of composition [VO(Q)2-n(HL1,2)n] (IIV) (where Q: C ₉H₆NO (quinolin-8-olato ion); HL¹: [C ⁶H4- (OH)CONHO] (salicyloylhydroxamate ion); HL²: [C ₆H₃(OH)(5-Cl)CONHO] (5-chlorosalicyloylhydroxamate); n = 1 and 2) have been synthesized by the reactions of [VO(Q)₂] with predetermined molar ratios of potassium salicyloylhydroxamate and 5-chlorosalicyloylhydroxamate in THF + MeOH solvent medium. The characterization of complexes has been accomplished by elemental analyses, molar conductivity, molecular weight determinations, magnetic measurements, electrochemical and IR, electronic, mass, and ESR spectral studies. The spectroscopic studies suggested bidentate nature of hydroxamate ligands involving O,O coordination. A square-pyramidal environment around vanadium has been proposed. The antimicrobial activity of newly synthesized complexes, ligands and precursor [VO(Q)₂] have been assayed against some pathogenic bacteria E. coli, S. aureus, S. typhi, S. paratyphi, S. epidermidis, and K. pneumoniae and fungi A. niger, B. fulva, and M. circinelloides by MIC method. The complexes exhibited improved antimicrobial activity over the free ligands. Cytotoxicity of complexes was studied on mammalian transformed cell line Hep2C, a derivative of human cervix carcinoma HeLa cells by MTT assay.