V(III) and V(IV) Schiff base complexes as potential insulin-mimetic compounds – Comparison, characterization and biological activity

Abstract

The syntheses of five vanadium complexes with ONO donor Schiff bases (L) along with analyses of obtained compounds were described: two [VO(L)(phen)] (phen = 1,10-phenanthroline) with V(IV) and three [V(L)2] with V(III). Ligands were derived from phenylacetic hydrazide and four aldehydes: 3-bromo-5-chloro-salicylaldehyde, 4-(diethylamino)-salicylaldehyde, 3,5-dichloro-salicylaldehyde and 3-metoxy-5-bromo-salicylaldehyde. The single crystal X-ray studies of both V(IV) complexes indicate on octahedral geometry of vanadium. The IR, UV–Vis (reflectance and in solution), cyclic voltammetry and magnetic moment measurements are presented and discussed. The stability of complexes in solutions of different pH was measured. Inhibition of human PTP1B phosphatase assays were performed for all obtained compounds and discussed in terms of their stability.