Syntheses, crystal structures and biological activity of oxidovanadium(V) complexes with tridentate aroylhydrazone ligands

A series of oxidovanadium(V) complexes, [VOLa-cL?] (L? = ethyl maltolate), were synthesized by reaction of VOSO4 with the aroylhydrazones 2-amino-N'-(2-hydroxybenzylidene)benzohydrazide (H2La), N'-(3-bromo-2-hydroxybenzylidene)-3-hydroxylbenzohydrazide (H2Lb) and N?-(2-hydroxy-5-nitrobenzylidene) pivalohydrazide (H2L (c)), respectively. The complexes were characterized by physico-chemical methods. Molecular structures of the complexes were further characterized by single crystal X-ray diffraction. The V ions in the three complexes are coordinated by three donor atoms of the aroylhydrazone ligands, two donor atoms of the ethyl maltolate ligand, and one oxo group. Biological study of the complexes indicates that they are insulin-like agents, which stimulated glucose utilization in a dose dependent manner over the concentration range 125??M to 1?mM.