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′-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.