Synthesis of calix[4]arene receptors incorporating (2,2′-bipyridin-6-yl)methyl and (9-methyl-1,10-phenanthrolin-2-yl)methyl chromophores and luminescence of their Eu3+ and Tb3+ complexes

Abstract

Several new calix[4]arene derivatives in the cone conformation 3–5 and 8–11, incorporating 2,2′-bipyridine or 1,10-phenanthroline chromophores have been synthesized in order to obtain luminescent complexes with Eu³⁺ and Tb³⁺. Whereas phenanthroline containing ligands 10 and 11 gave no indication of complex formation with lanthanide ions, the ligand 3 incorporating four 2,2′-bipyridine chromophores and the ligands 8 and 9, bearing two amide and two 2,2′-bipyridine groups, were able to sensitize Eu³⁺ and Tb³⁺ luminescence. The Tb³⁺ complex of compound 9 showed intense metal luminescence thanks to the high values of the molar absorption coefficient (ε= 29 000 dm³ mol^–1 cm^–1) and quantum yield (Φ= 0.12).