Luminescence and circularly polarized luminescence of macrocyclic Eu(III) and Tb(III) complexes embedded in xerogel and sol-gel SiO2 glasses

Luminescence, time-resolved luminescence, circularly polarized luminescence (CPL) and decay profiles of Ln(III) (15-crownether-5) (Ln = Ce, Sm, Eu, Tb) and Tb(III)-(R),(S)-cyclen derivative complexes doped in xerogel and sol-gel silica glasses are measured at temperatures down to 10 K to characterize luminescence properties and the electronic 2 (2) structure in the excited states. Luminescence spectral profiles and calculation of crystal field parameters (B-0((2)),B-2((2))) in the D-5(0) --> F-7(J)(J = 1, 2) transition give evidence of the fact that the pentagonal and planar structure of Eu(III) (15-crownether-5) does hold in xerogel and sol-gel glasses prepared at temperatures below 100degreesC. As annealing temperatures are increased from 80degreesC to 750degreesC, Eu(III) complexes in sol gel glasses are found to decompose gradually to SiO2:Eu3+. Tb(III)-(R) and (S)-cyclen derivative complexes in xerogel reveal at room temperature and 10 K sharp CPL spectra with luminescence dissymmetry factors g(lum) = -0.1 and 0.1, respectively. These complexes doped in sol-gel glasses represent luminescence characteristics of rare earth ions encapsulated in the nano-porous host. (C) 2002 Published by Elsevier Science B.V.