Dinuclear vanadium complexes with rigid phenylpolycarboxylate ligands: synthesis, structure, and catalytic bromination reaction with potential detection of hydrogen peroxide.

Vanadium complexes (VO)2(2,2′-bipy)2(bta)(H2O)2(1) and (VO)2(1,10-phen)2(bta)(H2O)2(2) (H4bta = 1,2,4,5-benzenetetracarboxylic acid, 2,2′-bipy = 2,2-bipyridine and 1,10-phen = 1,10-phenanthroline) have been synthesized by the reaction of V2(SO4)3, H4bta, 2,2′-bipy (for1) and 1,10-phen (for2) by hydrothermal methods. The complexes were characterized by elemental analysis, IR, UV–vis, thermogravimetric analyses, and single-crystal X-ray diffraction. Structural analyses indicate that1and2are both VO-bta-N-heterocycle system complexes. The central vanadium is coordinated by N2O4donors to form a distorted octahedral geometry. The complexes exhibit catalytic bromination activity in a single-pot reaction with conversion of phenol red to bromophenol blue in a mixed solution of H2O-DMF at 30 ± 0.5 °C with pH 5.8, indicating that they can be considered as a functional model of vanadium-dependent haloperoxidases. The practical application of H2O2detection has also been studied. Two oxovanadium complexes, (VO)2(2,2′-bipy)2(bta)(H2O)2(1) and (VO)2(1,10-phen)2(bta)(H2O)2(2) (H4bta = 1,2,4,5-benzenetetracarboxylic acid, 2,2′-bipy = 2,2-bipyridine and 10-phen = 1,10-phenanthroline), have been synthesized and characterized. The catalytic bromination activity and the practical application of H2O2detection have been studied. [ABSTRACT FROM AUTHOR]