NEW SENSITIZER-MODIFIED CALIX[4]ARENES ENABLING NEAR-UV EXCITATION OFCOMPLEXED LUMINESCENT LANTHANIDE IONS

The synthesis is described of a series of calix[4]arenes with three di fferent sensitizer chromophores (''antenna'') attached to the lower ri m via a short spacer. In the Eu3+ and Tb3+ complexes of these calixare nes, photoexcitation of the antenna can induce lanthanide emission via intramolecular energy transfer. Although the higher energy of the Tb3 + luminescent state makes it more difficult to sensitize than in the c ase of Eu3+, especially a triphenylene antenna is found to have strong sensitizing ability toward not only Eu3+ but also Tb3+, allowing exci tation of the lanthanide with wavelengths extending to 350 nm.