To understand the substituting group effects of organic ligands on the reaction equilibrium, the interactions between a diperoxovanadate complex [OV(O2)2(D2O)]－/[OV(O2)2(HOD)]－ (abbr. dpV) and a series of 3-substituted pyridines in solution 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. Some direct NMR data were given for the first time. The reactivity among the 3-substituted pyridines towards dpV takes the order of pyridine＞nicotinate＞N-methyl nicotinamide≈ methyl nicotinate. The competitive coordination results in the formation of a series of new six-coordinated peroxovanadate species [OV(O2)2L]n－ (L＝3-substituted pyridines, n＝1 or 2). The results of density functional calculations provided a reasonable explanation of the relative reactivity of the 3-substituted pyridines. Solvation effects play an important role in these reactions.

Key words: diperoxovanadate, 3-substituted pyridine, interaction, NMR, theoretical calculation