Journal of the American Chemical Society, Vol.117, No.37, 9408-9414, 1995
New Sensitizer-Modified Calix(4)Arenes Enabling Near-UV Excitation of Complexed Luminescent Lanthanide Ions
The synthesis is described of a series of calix[4]arenes with three different sensitizer chromophores ("antenna") attached to the lower rim via a short spacer. In the Eu3+ and Tb3+ complexes of these calixarenes, 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 case of Eu3+, especially a triphenylene antenna is found to have strong sensitizing ability toward not only Eu3+ but also Tb3+, allowing excitation of the lanthanide with wavelengths extending to 350 nm.