Antenna Effect in Eu3+ and Tb3+ Cryptates

Abstract

The absorption, emission, and excitation spectra, the excited state lifetimes (at 77 and 300 K, in H2O and D2O solution) and the emission quantum yields of some Eu3+ and Tb3+ cryptates are reported and compared with the corresponding properties of the Eu3+ and Tb3+ aquo ions. The cryptates examined are [M ⊂ 2.2.1]3+, [M ⊂ 2.2.1]3+−2F−, and [M ⊂ bpy.bpy.bpy]3+, where M stands for Eu3+ or Tb3+, 2.2.1 is the 4,7,13,16,21-pentaoxa−l,10-diazabicyclo−8,8,5-tricosane cryptand, and bpy.bpy.bpy is a macrobicyclic cryptand containing three 2,2{\textasciiacutex}-bipyridine groups. The possibility to design complexes exhibiting excellent absorption and luminescence properties is discussed on the basis of a detailed analysis of the above mentioned photophysical data.