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

Interactions between a bioactive diperoxovanadate complex K3OV(O2)2(C2O4)].H2O and pyridine in solution were studied by 2D NMR diffusion ordered spectroscopy (DOSY) as well as 1D 1H, 13C, 14N, and 51V NMR, variable temperature 1H NMR and spin-lattice relaxation time. Competitive coordination between C2O(4)(2-) and pyridine to OV(O2)(2)](-) were observed in solution. A new species OV(O2)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(O2)2(C2O4)](3-) and OV(O2)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.