Rare earth complexes in sol-gel glasses

The origin of the spectra of rare earth ions arising from f → f and f → d transitions is discussed. The parity-forbidden luminescence of lanthanide ions can be strongly intensified by excitation via molecules characterized by high transition probabilities. Such behaviour opens a route for creation of a class of new sophisticated materials. Luminescent materials based on heteroaromatic lanthanide cryptates are attractive as labels for advanced time-resolved fluoroimmunoassays and molecular markers, their potential use is also conceivable in the field of luminescent displays, molecular photonics and highly luminescent materials in hybrid organic/inorganic glasses. The recent findings of lanthanide complexes trapped in solgel inorganic glasses based on silica and zirconia networks are discussed and the theoretical basis of their spectroscopy is presented.