To understand the substitution group effects of organic ligands on the reaction equilibrium, the interactions between diperoxovanadate complex [OV(O2)2(D2O)]－/[OV(O2)2(HOD)]－ (abbr. bpV) and a series of substituted pyridines were explored using multinuclear (1H, 13C, and 51V) magnetic resonance, DOSY, and variable temperature NMR in 0.15 mol/L NaCl ionic medium for mimicking the physiological condition. The reactivity order among the substituted pyridines and bpV is picolinate＞isonicotinate＞methyl isonicotinate＞methyl picolinate. The competitive coordination results in the formation of a series of new six-coordinated (isonicotinate and methyl isonicotinate) or seven-coordinated (picolinate and methyl picolinate) peroxovanadate species [OV(O2)2L]n－ (L＝substituted pyridines, n＝1 or 2). Both the different substitution groups at the same position and the same groups at the different substitution position affect these reactions. The results of density functional calculations provide someway a reasonable explanation for the relative reactivity of the substituted pyridines. Solvation effects play an important role in these reactions.

Key words: diperoxovanadate, substituted pyridine, interaction, NMR, theoretical calculation