Intermolecular energy transfer between lanthanide complexes in aqueous solution—II: Transfer from terbium(III) to europium(III) complexes of phthalic and hemimellitic acids

Abstract

Intermolecular energy transfer, emission lifetimes, and emission intensity have been used as probes to examine the aqueous solution chemistry of terbium(III) complexes of phthalic and hemimellitic acids. The energy transfer was found to be an excellent probe of these systems and is sensitive toward intermolecular interactions among lanthanide complexes in solution. From comparison of dynamic and static quenching data, it was possible to demonstrate the existence of associated Tb 3+/ligand complexes at medium pH and to show that this association was absent at low pH values. These results imply that definitive statements regarding the stereochemistry of lanthanide ion complexes in aqueous solution cannot be made with certainty, but that general speculations regarding probable modes of bonding are possible.