Luminescent properties of diketonates of trivalent europium with dimethyl sulfoxide

Photoluminescent properties of the tris(thenoyltrifluoroacetonate)europium( III) dihydrate with dimethyl sulfoxide (DMSO), in the solid state, are repo rted. The compound Eu(TTA)(3). 2DMSO and the precursor salt were characteri zed by IR spectroscopy, differential scanning calorimetry and elemental ana lysis. The emission data indicate that the substitution of the two water mo lecules by DMSO ligand in the complex causes an intensification of luminesc ence corresponding to the D-5(0) --> F-7(J) (J = 0-4) transitions associate d with one of the site symmetries. Large values of the Omega(2) intensity p arameter (35.2 x 10(-20) cm(2)) were obtained, reflecting the hypersensitiv e character of the D-5(0) --> F-7(2) transition and indicating that Eu3+ io n is in a highly polarizable chemical environment. This is consistent with systems containing sulfoxide ligands DBSO and PTSO. The DMSO complex also s hows a higher value for the Omega(4) parameter (6.8 x 10(-20) cm(2)) as a c onsequence of the difference in the basicity of the oxygen donor ligand. Li fetime measurements (tau = 0.72 ms) confirm that the Eu3+ luminescence has a higher efficiency than in the case of the hydrated compound. (C) 2000 Els evier Science S.A. All rights reserved.