The trivalent cations of the lanthanides have photoluminescent properties that are favorable for several kinds of applications. However, it is difficult to generate this luminescence by direct excitation of the lanthanide ion, because of the ions' poor ability to absorb light. Organic chromophores do a better job at absorbing light. The energy absorbed by such chromophores can be transferred to a nearby lanthanide ion, which is then able to emit its characteristic luminescence. The organic chromophore acts like some sort of 'antenna'
Various lanthanide complexes containing organic antennae are known to show efficient photoluminescence. The basic architecture of these systems is depicted in the picture below.
Typical emission spectra of luminescent lanthanide complexes containing antenna chromophores are shown below. The emissions are coming from terbium(III), dysprosium(III), europium(III) and samarium(III), respectively. The antenna was excited at 337 nm.
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