Complexes of vanadium(III) with aromatic amino acids and l-proline in aqueous solution

The equilibria of the complexation processes of V3+ ion with l-phenylalanine, l-tyrosine, l-tryptophan and l-proline in aqueous solution were studied by potentiometric and spectroscopic (UV, Vis, CD) methods. The results indicate that all ligands (except l-tyrosine) form only 1:1 species with vanadium(III) ion in the pH range about 2–5. More complex equilibria were observed in the vanadium(III)–l-tyrosine system. Only in this system relatively stable ML2 species predominantly exists in the pH range 3–5. The results of spectroscopic measurements indicate that in ML and ML2 species chelated bounds through O and N atoms appear in all investigated systems. Above pH 5 strong hydrolysis processes of vanadium(III) occurred.

The equilibria of the complexation processes of V3+ ion with l-phenylalanine, l-tyrosine, l-tryptophan and l-proline in aqueous solution were studied by potentiometric and spectroscopic (UV, Vis, CD) methods. The complexes are relatively weak and hydrolysis of vanadium(III) significantly influenced on complexation process. Only in the vanadium(III)–tyrosine system relatively stable ML2 species predominantly exists in the pH range 3–4.5.Figure optionsDownload as PowerPoint slide