Luminescence investigation of the Sm(III)-β-diketonates with sulfoxides, phosphine oxides and amides ligands

In this paper we report on a photoluminescent investigation of complexes involving Sm3+ -beta-diketonates with sulfoxides, phosphine oxides and amides ligands. In the synthesis of the coordination compounds we used samarium tris(thenoyltrifluoroacetonate) dihydrated precursor with the following ligands (L): DBSO and PTSO sulfoxides; TPPO phosphine oxide and (PHA) N-phenylacetamide. They have shown high orange luminescence characteristic of the Sm3+ ion. The emission spectra of the Sm3+-complexes present narrow bands arising from the (4)G(5/2) --> H-6(J) (J=5/2, 7/2, 9/2, 11/2) transitions with the hypersensitive (4)G(5/2) --> H-6(9/2) transition as a prominent group. It is observed an efficient intramolecular energy transfer from the triplet state (T) of the ligands to the emitting (4)G(5/2) state of the Sm3+ ion. The experimental intensity parameters and (eta(Sm) and eta(Eu)) for the Sm and Eu complexes have been determined and compared. The lifetimes (tau) of the emitting level (4)G(5/2) of the Sm-complexes are approximately 10 times higher than in the precursor compound [Sm(TTA)(3) . (H2O)(2)] indicating that radiative processes are operative in all the compounds due to the absence of multiphonon relaxation by coupling with the OH oscillators. (C) 2002 Elsevier Science B.V. All rights reserved.