THERMODYNAMICS OF LANTHANIDE QUINOLINATE COMPLEXATION IN AQUEOUS-SOLUTION

The thermodynamic parameters (DELTA-G101, DELTA-H101 and DELTA-S101) of formation of 1:1 complexes between lanthanide cations and quinolinate have been measured using potentiometric and calorimetric techniques in aqueous solution of 0.50 M (NaClO4) ionic strength at 25-degrees-C. The thermodynamic data are discussed and are found to indicate a structure in which the quinolinate ligand is coordinated to the lanthanide cation by forming a chelate through the ring nitrogen atom at position 1 and the carboxylate group at position 2 of the pyridine ring.