Coordination abilities of three donor groups ligand, DL-2-amino-3-phosphonopropionic acid, in copper(II) heteroligand complexes with polyamines: Implications for metal ions coordination in aqueous solution

Solution equilibrium studies on the Cu(II)-polyamine-DL-2-amino-3-phosphonopropionic acid (β-Asp(P)) ternary systems (polyamine: ethylenediamine, diethylenetriamine, N,N,N′,N″,N″-pentamethyldiethylenetriamine) have been performed by pH-potentiometry, UV-Vis spectrophotometry and EPR methods. The results indicate the tridentate coordination mode of β-Asp(P) for the [Cu(en)(β-Asp(P))]− species. [Cu(dien)(β-Asp(P))]− and [Cu(Me5dien)(β-Asp(P))]− are five-coordinate complexes in which β-Asp(P) coordinates to the copper(II) ion in the amino acid manner with the formation of five-membered chelate ring.