Aminoacid-derivatized oxidovanadium complexes: Synthesis, structure and bromination reaction activity

A new family of aminoacid-derivatized oxidovanadium complexes as potential functional model of vanadium haloperoxidases: [(VO)-O-V(sal-phe)(OMe) (MeOH)] (1), [(VO)-O-IV(sal-ala)(2,2'-bipy)]center dot H2O (2), [(VO)-O-IV(sal-ala)(1,10-phen)]center dot 0.5H(2)O (3) and [(VO)-O-IV(sal-his)(1,10-phen)]center dot 2MeOH (4) (H(2)sal-phe = Schiff base derived from salicylaldehyde and DL-beta-phenylalanine, H(2)sal-ala = Schiff base derived from salicylaldehyde and DL-alpha-alanine, H(2)sal-his = Schiff base derived from salicylaldehyde and L-histidine) have been synthesized. All the complexes were characterized by elemental analysis, IR spectra and UV-Vis spectroscopy. In particular, molecular structures of three representative complexes (1, 2 and 3) were determined by X-ray crystallography. In addition, bromination reaction activity of the starting material and the complexes has been tested by a method with phenol red as organic substrate in the presence of H2O2, Br and phosphate buffer, the studying results indicate that the vanadium complexes can catalyze the visible conversion of phenol red to bromophenol blue under weak-acid conditions and the different structural characterizations of the complexes exhibit different catalytic activity, therefore, the complexes can be considered as a potential functional model of VHPO. (C) 2011 Elsevier B.V. All rights reserved.