Thermodynamic study of mixed-ligand complex formation of copper(II) and nickel(II) nitrilotriacetates with dipeptides in solution

• Stable mixed ligand complexes of MNta with dipeptides at physiological pH value.
• The thermodynamic and spectrophotometric data evident the various coordination mode of dipeptides.
• NH2, CO-coordination mode of dipeptides in complexes MNtaL.
• NH2, N−- or NH2, N−, COO-coordination modes of dipeptides in complexes MNtaLH−1.

The mixed-ligand complex formation in the systems M2+–Nta3−–L− (M = Cu, Ni; L = GlyGly, AlaAla) has been calorimetrically, pH-potentiometrically and spectrophotometrically studied in aqueous solution at 298.15 K and the ionic strength of I = 0.5 (KNO3). The thermodynamic parameters of formation of the MNtaL2− and MNtaLH-13- complexes have been determined. The probable coordination mode of the complexone and dipeptide molecules in the mixed-ligand complexes was discussed.

The mixed ligand complex formation of copper(II) and nickel nitrilotriacetates with dipeptides containing the glycine and alanine residues has been investigated by means of calorimetry, pH-potentiometry and Vis spectroscopy. The received data evident various coordination modes of dipeptides in complexes MNtaL (NH2, CO-coordination) and MNtaLH−1 (NH2, N−- or NH2, N−, COO-coordination). The formation of stable mixed complexes of MNta with dipeptides at physiological pH value should be accounted during chelation therapy.Figure optionsDownload as PowerPoint slide