Spectroscopic properties of a new light-converting device Eu(thenoyltrifluoroacetonate)(3) 2(dibenzyl sulfoxide). A theoretical analysis based on structural data obtained from a sparkle model

We report the synthesis, characterization and spectroscopic properties of the compound Eu(thenoyltrifluoroacetonate)(3) 2(dibenzyl sulfoxide) which is highly luminescent under UV excitation. Experimental and theoretical results on ligand field parameters, 4f-4f intensities and intramolecular energy transfer processes are described. The characteristic emission spectrum of the Eu3+ ion shows a very high intensity for the hypersensitive D-5(0) --> F-7(2) transition, pointing to a highly polarizable chemical environment around the Eu3+ ion. No emission at low temperature from the organic part of the compound is observed, in contrast to the case of the analog compound with Gd3+, indicating that energy transfer from the ligands to the Eu3+ ion is quite efficient. Lifetime measurements confirm that the Eu3+ luminescence has a higher efficiency than in the case of the hydrated compound (two water molecules in the place of the dibenzyl sulphoxides). The theoretical calculations are based on an optimized coordination geometry and electronic structure obtained from the SMLC/AM1 (Sparkle Model for the calculation of lanthanide complexes within the Austin Model 1), recently introduced in the literature, and ligand field and 4f-4f intensity models previously developed. A comparison with experiment is made. Considerably high values of intramolecular energy transfer rates are predicted.