Tridentate hydrazido-hydrazones vanadium complexes. Synthesis, properties and biological activity

Abstract

Nine new vanadium complexes, with tridentate Schiff base ligand based on 3,5-di-tert-butyl-2-hydroxybenzaldehyde and different hydrazides, are described and characterized. The X-ray crystal structure of complex 8 shows distorted octahedral geometry of vanadium, with ONO ligand in equatorial position. The tridentate Schiff base ligand forms six membered and five-membered chelate rings at the V(V) acceptor center, with the corresponding bite angles being 82.97(9)˚ and 74.48(9)˚. The molecules are gathered by means of intermolecular O-H∙∙∙N hydrogen bond and layered by π∙∙∙π interactions involving the pyridine and phenolate rings. Such interactions expand the structure along the crystallographic a axis. The complexes were characterized by the elemental analyses, IR, UV-Vis, EPR spectroscopy, cyclic voltammetry, thermogravimetry and magnetic susceptibility measurements. The stabilization role of co-ligands is discussed. The cytotoxicity versus HepG2 hepatocytes and inhibition of human recombinant PTP1B was studied.

Characterization and antidiabetic activity of salicylhydrazone Schiff base vanadium(IV) and (V) complexes

“…Usually, in our previous investigations with vanadium complexes based on Schiff base ligands, oxidation of V(IV) to V(V) when co-ligand (for example, phen) was not used [22,23,25,27,28] was observed. In this part of the investigation, the oxidovanadium(IV) complexes (1, 9, 11, 12, 18, 23) were obtained, among others, for which there was no change in the oxidation state and for which a stabilizing ligand for the V(IV) oxidation state was not used in the synthesis.…”

“…We present herein the synthesis and physicochemical characterization of vanadium(IV,V) complex with tridentate ONO hydrazone Schiff base ligands, now extended to those based on 5-nitrosalicylaldehyde, 5-methoxysalicylaldehyde, and 5-sulfosalicylaldehyde with a set of hydrazides used by us previously [20][21][22][23][24][25][26][27][28]. As shown earlier, for tridentate contrary to bidentate ligands, a huge change of biological activity is observed, indicating that complexes in unchanged form (or at least with ONO ligand still coordinated to vanadium) pass into cells.…”