Effect of Ionic Strength, Aquo-Organic Solvents, and Temperature on the Stabilities of N-[Tris(hydroxymethyl)methyl]glycine + Metal Complexes

The stability constants of complexes of N -[(tris-hydroxymethyl)methyl]glycine (Tricine) with the transition metal ions Co 2+, Ni 2+, Cu 2+, and Zn 2+ were studied potentiometrically in the presence of (0.02, 0.05, 0.10, and 0.15) mol dm -3 KNO 3; in the presence of (60, 65, and 75) vol % acetone, 75 vol % ethanol, and 75 vol % dioxane at 0.05 mol dm -3 KNO 3 at 25 °C; and at (5, 15, 25, 35, 45) °C in the presence of 0.1 mol dm -3 KNO 3 . The thermodynamic stability constants for tricine and for tricine + M(II) [where M(II) = Co 2+, Ni 2+, Cu 2+, and Zn 2+ ) have been obtained from the measurements.