Effect of phosphonic acid substituents on europium(III) complex stability in acidic solutions.

摘要

The thermodynamics of protonation and europium(III) complex formation with substituted methane diphosphonic acids have been reported recently. These ligands form strong complexes with europium in moderately acidic solutions ((H(sup +)) (ge) 0.1 M), conditions not conducive to complexation by most carboxylate and aminopolycarboxylate ligands. A correlation of log (beta) vs pK(sub a) values for phosphonate and carboxylate ligands is used to explore the effect of ligand structure on complex stability. 5 refs., 1 fig.