LUMINESCENCE STUDY OF EUROPIUM(III) COMPLEXES WITH SEVERAL DICARBOXYLIC-ACIDS IN AQUEOUS-SOLUTION

Luminescence lifetimes of Eu(III) in complexes with dicarboxylate liga nds and N, O or S donors have been measured in H2O and D2O solutions o f varying pH and europium-ligand ratio. The ligands were iminodiacetat e (IDA), diglycolate (DGA), thiodiglycolate (TDA), dipicolinate (DPA), benzene-1, 2-bis(oxyacetate) (BDODA), ethylenediaminediacetate (EDDA) and ethylene-1, 2-dithiodiacetate (EDTDA). The lifetimes have been us ed to measure the number of water molecules coordinated to the Eu(III) ion in each complex. The results show that in the 1:1 and 1:2 complex es the ligands: IDA, DGA and DPA are tridentate whereas the TDA comple xes are bidentate. BDODA and EDDA form tetradentate 1:1 and bidentate 1:2 complexes, while EDTDA is bidentate in both the 1:1 and 1:2 comple xes. These results indicate that the nitrogen and oxygen donors are bo nded to lanthanide ions in the DGA, IDA, DPA and EDDA complexes, where as the sulfur donors are not bonded in the TDA and EDTDA complexes.