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Influence of the N-[methylpyridyl]acetamide ligands on the photoluminescent properties of Eu(III)-perchlorate complexes

2002; Elsevier BV; Volume: 21; Issue: 18 Linguagem: Inglês

10.1016/s0277-5387(02)01032-x

1873-3719

Ercules E. S. Teotônio, José G.P. Espı́nola, Hermi F. Brito, Oscar L. Malta, Severino F. de Oliveira, Dalva Lúcia Araújo de Faria, Celly M. S. Izumi,

Magnetism in coordination complexes

This work reports the synthesis, characterization and spectroscopic studies of Eu(III)-perchlorate complexes with amide ligands derived from N-[x-methylpyridyl]acetamide where x=3, 4 and 6. The Eu(ClO4)33(x-mpa) complexes were characterized by elemental analyses, molar conductance, TG analyses and vibrational spectroscopy. Raman and infrared data show that the perchlorate ion, (ClO4 −), is bonded to Eu(III) as a monodentate ligand and that in these three complexes water molecules are not coordinated to the rare earth ion. The profiles of the emission spectra of the complexes with 3- and 4-mpa ligands are very similar but they differ from the complex containing 6-mpa ligand. This spectroscopic behavior can be rationalized in terms of the Ωλ (λ=2 and 4) and R02 experimental intensity parameters. The values of Ω2 (∼6.5×10−20 cm2) in these complexes are smaller than in Eu(III)-TTA compounds (Ω2∼35.0×10−20 cm2), indicating that in the former case the rare earth ion is in a chemical environment less polarizable. Lifetime and emission quantum efficiency measurements for the emitting level 5D0 were carried out and the results are discussed.