Synthesis, characterization and glucose-lowering studies of air-stable, mixed-ligand vanadium(III) acetylacetonates and oxidovanadium(IV) complexes containing pyridine-based ligands.

The glucose-lowering properties of five acetylacetonate complexes of vanadium(III) containing picolinate (pyridine-2-carboxylate)/1,10-phenanthroline/2,2'-bipyridyl as co-ligands and three oxidovanadium(IV) complexes have been examined by in vivo experiments on the streptozotozin (STZ)-diabetic rat model and compared against the benchmark compound, bis(maltolato)oxidovanadium(IV). The bipyridyl and the picolinate complexes exhibit more significant activities than the phenanthroline complexes. The single crystal X-ray structures of three new complexes (acetylacetonato)bis(pyridine-2-carboxylato)vanadium(III), bis(methanol)(pyridine-2,6-dicarboxylato)oxidovanadium(IV) and (acetylacetonato)(1,10-phenanthroline)(thiocyanato)oxidovanadium(IV) are established in this work. The syntheses, spectral and electrochemical properties of all the complexes are discussed.