Effective modulation of lanthanide luminescence functions via stereo-controlled ligand synthesis: Effects of ligand chirality on lanthanide anion sensing

A new synthetic approach to specific ligands for lanthanide coordination and luminescence sensing is reviewed: stereo-controlled synthesis of tripodal ligands; their lanthanide complexation; and chirality tuning of anion-responsive luminescence functions. A series of tris(2-pyridylmethyl)amine ligands was synthesized in a stereo-controlled fashion. They formed stable complexes with several lanthanide cations via cooperative action of three pyridine donors and tertiary nitrogen atom. Their Eu3+ and Tb3+ complexes gave intense luminescence signals, the intensity of which was specifically amplified by the addition of external guest anions. The use of stereo-controlled ligands effectively enhanced the anion sensitivity in lanthanide luminescence sensory process. Since this type of chiral lanthanide complexes offered visual sensing of Cl- or NO3- anion, further combinations of stereo-controlled ligands and functional lanthanide centers have broad applications in the generation of novel lanthanide functions. (C) 2003 Elsevier B.V. All rights reserved.