Interactions of vanadium with amino acids—Monodentate coordination of vanadyl proline, lysine and histidine and catalytic degradations of methyl orange

Vanadyl proline [VO(Hpro)(SO4)(H2O)3] (1, Hpro = proline), lysine trans-[VO(H2lys)2(H2O)3]Cl4·H2O (2, Hlys = lysine) and histidine [VO(H2his)(2,2′-bipy)(H2O)2]Cl3·H2O (3, Hhis = histidine) have been obtained in acidic conditions. Proline, lysine and histidine in 1–3 feature monodentate coordination with vanadium(IV) through carboxy groups respectively. The complexes are well characterized by elemental analysis, UV–Vis, IR, EPR, TG, X-ray structural analyses and bond valence calculations (BVS). The interactions between vanadium and amino acids are compared between 1–3 and other similar transition metal amino acids. Solution NMR spectra show the coordination of amino acids in solution. Moreover, 1 and 2 show good catalytic activities for the degradations of methyl orange (MO) with H2O2.