Luminescent molecular sensors based on analyte coordination to transition-metal complexes

Recent research towards luminescent molecular chemosensors in which sensing is achieved via binding of analytes as ligands to metal-based receptors is described. In some cases, the metal complex acts both as receptor and lumophore; in others, a pendant lumophore is coordinated to the metal receptor. Analyte binding can occur at a vacant coordination site on the metal chemosensor, or alternatively by displacement of a weakly bound ligand. In the latter case, hemilabile ligands, in which the displaced ligand remains attached to the complex upon analyte binding, have also been used. Examples of each of these approaches to metal-based chemosensors are discussed. (C) 2002 Elsevier Science B.V. All rights reserved.