resumo
Lanthanide-based coordination compounds of molecular formula [Ln(keto)(3)(H2O)], where Ln=Gd, Eu and keto=ketoprofen, were synthesized and their photoluminescence features were detailed in the 12-300 K interval. The emission spectra of [Eu(keto)(3)(H2O)] reveal a strong dependence with the temperature, well-illustrated by an unusual large blue-shift (similar to 17 cm(-1)) of the D-5(0)-> F-7(0) transition as the temperature is raised. The arithmetic difference between the absorption spectrum of [Eu(keto)(3)(H2O)] with that of [Gd(keto)(3)(H2O)] pointed out the presence of a ligand-to-metal charge transfer (LMCT) band (320-370 nm). From the [Gd(keto)(3)(H2O)] phosphorescence the energy of the keto-related triplet states was determined showing a large overlap with the intra-4f(6) levels and a strong electron-phonon coupling. The high-resonance between the LMCT and triplet states and the Eu3+ levels leads to a strong dependence of the D-5(0) lifetime value, typical of the presence of operative energy transfer processes. (C) 2015 Elsevier B.V. All rights reserved.
palavras-chave
TEMPERATURE-MEASUREMENTS; SENSITIZED LUMINESCENCE; TRIVALENT LANTHANIDES; EUROPIUM(III) IONS; SOLID KETOPROFEN; IN-VITRO; COMPLEXES; FLUORESCENCE; LINEWIDTH; LIFETIMES
categoria
Optics
autores
Lahoud, MG; Frem, RCG; Galico, DA; Bannach, G; Nolasco, MM; Ferreira, RAS; Carlos, LD
nossos autores
Luís Carlos
Professor Catedrático
Maria Rute de Amorim e Sá Ferreira André
Professor Catedrático
Mariela Martins Nolasco
Investigador AuxiliarGrupos
G2 - Materiais Fotónicos, Eletrónicos e Magnéticos
G6 - Materiais Virtuais e Inteligência Artificial
agradecimentos
This work is partially developed in the scope of the project CICECO-Aveiro Institute of Materials (Ref. FCT UID/CTM/5001/2013), financed by Portuguese funds through FCT/MEC and when applicable co-financed by FEDER under the PT2020 Partnership Agreement. M.M.N. (BPD/UI96/3340/2014) also acknowledge the post-doctoral scholarship under the Project Mais Centro - PORC, CENTRO-07-ST24-FEDER-002032. CAPES and CNPq foundations (Brazil) are also acknowledged for their general funding scheme.