Metal complexes as components of luminescent signalling systems

Freshly developing lines of research in luminescent signalling with metal c omplexes over the last year are critically discussed. Metal-containing moie ties are found to serve as remarkable lumophores with delayed emission and also as efficient receptors especially for anionic species. The photophysic al concepts of metal-centred (MC) excited states, metal to ligand charge tr ansfer (MLCT) excited states, metal-metal to ligand charge transfer (MMLCT) excited states, photoinduced electron transfer (PET) processes and electro nic energy transfer (EET) processes are all being exploited during these si gnalling operations. Novel sensors and switches are emerging as a result. ( C) 1999 Elsevier Science S.A. All rights reserved.