Synthesis, Spectroscopic Characterization, Catalytic and Biological Activity of Oxidovanadium(V) Complexes with Chiral Tetradentate Schiff Bases.

New oxidovanadium(V) complexes, VOL 1 - VOL 10 , with chiral tetradentate Schiff bases obtained by monocondensation reaction of salicylaldehyde derivatives with 1 S ,2 S -(+)-2-amino-1-(4-nitrophenyl)-1,3-propanediol. All complexes have been characterized using different spectroscopic methods, viz. IR, UV-Vis, circular dichroism, one- ( 1 H, 51 V) and two-dimensional (COSY, NOESY) NMR spectroscopy, and elemental analysis. Furthermore, the catalytic ability of all compounds in the epoxidation of styrene, cyclohexene, and its naturally occurring monoterpene derivatives, i.e., S (-)-limonene and (-)-α-pinene has also been studied, using two different oxidants, i.e., aqueous 30% H 2 O 2 or tert -butyl hydroperoxide (TBHP). In addition, the biological properties of these chiral oxidovanadium(V) compounds, but also cis -dioxidomolybdenum(VI) complexes with the same chiral Schiff bases, were studied. Their cytotoxic and cytoprotective activity studies with the HT-22 hippocampal neuronal cells revealed a concentration-dependent effect in the range of 10-100 μM. Moreover, vanadium(V) complexes, in contrast to cis -dioxidomolybdenum(VI) compounds, demonstrated higher cytotoxicity and lack of cytoprotective ability against H 2 O 2 -induced cytotoxicity.