LUMINESCENCE PROPERTIES OF CRYPTATE EUROPIUM(III) COMPLEXES INCORPORATING HETEROCYCLIC N-OXIDE GROUPS

The luminescence spectra, lifetimes, and quantum yields of the cryptate-type complexes [Eu subset-of 1]3+ and [Eu subset-of 2]3+, where 1 and 2 are cryptand-type ligands containing two 2,2'-bipyridine (bpy) and one 2,2'-bipyridine-1,1'-dioxide (bpyO2) units (1) or two bpy and one 3,3'-biisoquinoline-2,2'-dioxide (biqO2) units (2), have been measured in H2O and D2O at 77 and 300 K. The luminescence quantum yield upon excitation in the ligand-centered bands is much higher than that exhibited by the previously investigated [Eu subset-of bpy.bpy.bpy]3+ cryptate. The role played by various radiative and non-radiative paths is discussed.