Spectroscopic studies on the interactions between a bioactive diperoxovanadate complex and pyridine

Interactions between a bioactive diperoxovanadate complex K-3[OV(O-2)(2)(C2O4)].H2O and pyridine in solution were studied by 2D NMR diffusion ordered spectroscopy (DOSY) as well as 1D H-1, C-13, N-14, and V-51 NMR, variable temperature H-1 NMR and spin-lattice relaxation time. Competitive coordination between C2O42- and pyridine to [OV(O-2)(2)](-) were observed in solution. A new species [OV(O-2)(2)(Py)](-) was formed and its NMR data were reported for the first time. The experimental results indicated that both of the vanadium atom in species [OV(O-2)(2)(C2O4)](3-) and [OV(O-2)(2)(Py)](-) are six coordinated in solution. The conclusion was further supported by the results of ESI-MS. The newly-formed species is stable under the condition of near physiological pH value. (C) 2003 Elsevier B.V All rights reserved.