Synthesis and Luminescence of Eu(3+) and Tb(3+) Complexes with Novel Calix[4]arene Ligands Carrying 2,2'-Bipyridine Subunits

Eu3+ and Tb3+ complexes with novel branched cali[4]arene ligands incorporating 2,2'-bipyridine subunits functionalized in the 6- or 5,5'-positions have been synthesized and their photophysical properties investigated. High luminescence intensity was obtained for the Eu3+ complex of the calix[4]arene ligand carrying four 5,5'-substituted-2,2'-bipyridines, which has high molar extinction coefficients (epsilon(max) = 39 600 M(-1) cm(-1)) and a high luminescence quantum yield (15%)