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.