Mono- and dioxido-vanadium(V) complexes of a tridentate ONO Schiff base ligand: Synthesis, spectral characterization, X-ray crystal structure, and anticancer activity

Three oxido-vanadium(V) complexes, [VO2(L)][NH(Et)3] (1), [VO(L)(PrO)] (2) and [VO(L)(BuO)] (3), containing deprotonated form of the tridentate Schiff base ligand 1-(((5-chloro-2-oxidophenyl) imino)methyl)naphthalen-2-olate [L2] have been synthesized and characterized using elemental analysis, molar conductivity, FTIR, 1H NMR analysis, and electronic spectroscopy. The structures of the free H2L ligand and all the complexes were determined by single crystal X-ray diffraction. According to the spectroscopic and structural data, H2L exists in the solid state in a zwitterionic form. In all the complexes, the V(V) center is coordinated by the ONO donor set of the L2 ligand, one or two oxido groups and in the case of 2 and 3 by one alkoxide group (PrO for 2 and BuO for 3) in a distorted square pyramidal geometry. The anticancer activities of the title complexes have been also investigated against MCF-7 (breast cancer) cells and compared with that of VO(acac)2. According to the obtained results, all the complexes possess higher anticancer activity than VO(acac)2.