Spectroscopic Characterization and Properties of Some Bioactive- Peroxovanadium Complexes in Aqueous Solution

Four bioactive peroxovanadium(pV) complexes bpV(ox), bpV(bipy), bpV(phen) and bpV(pic), (VO(O_2)_2L] n-, where ligand L=oxalic acid dianion(ox), bipyridine(bipy), 1,10-phenanthroline(phen), and pyridine-2-carboxylic acid(pic), were synthesized and characterized by 51V NMR, 1H NMR, 13C NMR, ESI-MS, IR and elemental analysis. All 1H and 13C peaks were assigned by 2D 1H-1H COSY, HMQC and HMBC. Their stereochemical structures in solution were discussed according to the NMR signals of organic ligands. The descending stability order of complexes in aqueous solution determined by 51V NMR is bpV(phen), bpV(bipy), bpV(pic) and pV(ox). The predominant decomposition patterns of these complexes were proposed on the basis of electrospray ionization MS (ESI-MS) and 51V NMR. This work will facilitate the studies of interactions between pV complexes and target biomolecules in solution so as to clarify structure-function relationship of these bioactive complexes.