Tridentate ONO ligands in vanadium(III-V) complexes - synthesis, characterization and biological activity

Abstract The synthesis, properties, including single crystal structures and biological activity of 16 new vanadium complexes with tridentate ONO Schiff base ligands L based on 5-chloro- and 5-hydroxy-salicylaldehyde and selected hydrazides are presented. Several types of complexes were synthesized at different oxidation state of vanadium: [VO(L)(phen)] (where phen denote 1,10-phenanthroline) with V(IV), [VO(L)(solv)] (where solv denote solvent molecule H2O or EtO−) with V(IV or V), [VO2L] and [VOL(H2O)2] with V(V) and [VL2] with V(III). All complexes were characterized by elemental analysis, IR, UV-Vis, EPR spectroscopy, cyclic voltammetry and thermogravimetric measurements. The molecular structures of two V(V) complexes were confirmed by single-crystal X-ray diffraction. The stability of complexes in solution as well as the biological activity - inhibition of human tyrosine phosphatases, were investigated and discussed.