Thermodynamic study of mixed-ligand complex formation of copper(II) and nickel(II) nitrilotriacetates with amino acids in solution. I

Mixed-ligand complex formation in the system M2+–Edta4−–L− (M = Cu, Ni; L = His, Lys, Orn, Im) has been calorimetrically, pH-potentiometrically and spectrophotometrically studied in aqueous solution at 298.15 K and with an ionic strength of I = 0.5 (KNO3). The thermodynamic parameters of formation of the MEdtaL, MEdtaHL and (CuEdta)2L complexes have been determined. The probable coordination mode of the complexone and the amino acid residue in the mixed-ligand complexes has been discussed.

Graphical abstractThe mixed ligand complex formation of copper(II) and nickel(II) nitrilotriacetates with basic amino acids (L = His, Orn, Lys, Im) has been investigated by means of pH-potentiometry, calorimetry and spectrophotometry. The received data evidences various coordination modes of the amino acids in the mixed complexes. The formation of stable mixed complexes of metal complexonates with amino acids at physiological pH value should be accounted for during chelation therapy.Figure optionsDownload full-size imageDownload as PowerPoint slide