Encapsulation of Lanthanide Ions in Calixarene Receptors. A Strongly Luminescent Tb(3+) Complex

Complexes in which the Eu3+, Tb3+, and Gd3+ ions are encapsulated in the p-t-butylcalix[4]arene-tetra-acetamide ligand, (1) have been synthesized and their photophysical properties investigated; the Tb3+ complex exhibits a high luminescence quantum yield (0.2) and a long luminescence lifetime (1.5 ms) upon ligand excitation in aqueous solution