ENHANCED EU-III ION LUMINESCENCE AND EFFICIENT ENERGY-TRANSFER BETWEEN LANTHANIDE CHELATES WITHIN THE POLYMERIC STRUCTURE IN AQUEOUS-SOLUTIONS

Four new binucleating symmetric; bis(4-pyridine-2,6-dicarboxylic acids ) have been synthesized and luminescence enhancement of their Eu-III c omplexes by Y-III ions observed. The results indicate that the mechani sm of enhancement is based on the formation of a polymeric structure w here Eu-III ions and Y-III ions are linked together by the ligands wit h the consequent;transfer of absorbed energy along the polymer chain t hrough several ligands toward the Eu-III ion. The mechanism of energy transfer is probably different from the previously reported micellar c o-luminescence where energy transfer occurs via the Forster dipole-dip ole mechanism.