Thermodynamics of mixed-ligand complexation of gadolinium ethylenediaminetetraacetate with amino acids in aqueous solution

Mixed-ligand complexation of GdEdta− with glycinate, L-glutamate, DL-aspartate, iminodiacetate, and nitrilotriacetate anions in aqueous solutions at 298.15 K and the ionic strength I = 0.5 (KNO3) was studied. The thermodynamic parameters (logK, ΔrG, ΔrH, ΔrS) of these reactions were determined from calorimetric and pH-metric data. The most probable way of coordination of the amino acids in the heteroleptic complexes is discussed.