Luminescence of a new Tm3+ β-diketonate compound

This work reports the results for the synthesis, characterization and photophysical properties of a new Tm(ppa)(3). 2H(2)O complex (ppa = 3-phenyl-2,4-pentanedionate). Its characterization was carried out by EDTA titration and TGA analysis, which indicates the presence of the tris-beta-diketonate complex with two water molecules completing the metal coordination sphere. The photophysical analyses of the Tm(ppa)(3). 2H(2)O complex were carried out at room (25 degrees C) and liquid nitrogen (77 K) temperatures. Excitation and absorption spectra showed a broad band centered at similar to 335 nm which is ascribed to the complex, since the ppa absorbance maximum is centered at 296 nm. The emission spectra (lambda(ex) = 335 nm) presented the characteristic bands of Tm3+ due to the (1)G(4)-->H-3(6) (478 nm), (1)G(4)-->F-3(4) (650 nm), (1)G(4) --> H-3(5) (770 nm) and H-3(4)-->H-3(6) (790 nm) transitions. A pyridine adduct was also prepared but no spectral features could be observed in it. The Gd(ppa)(3).2H(2)O was synthesized in order to determine the triplet state of the ppa. (C) 1998 Elsevier Science S.A.