resumo
The [RE(NTA)(H2O)(2)]-(H2O) rare-earth complexes (RE3+: Eu, Gd, Tb and NTA: nitrilotriacetate) were synthesized and characterized by elemental analysis, thermogravimetry, X-ray diffraction, and infrared spectroscopy. The complexes show high crystallinity and thermostability. The photoluminescence behavior was studied based on the excitation and emission spectra, and luminescence decay curves. The compounds exhibit red (Eu3+), green (Tb3+) and UV (Gd3+) monochromatic emissions under UV excitation. The NTA ligand acts as luminescence sensitizer in the ligand-toRE(3+) intramolecular energy transfer process, owing to the fact that the first excited triplet state (Ti : 29 000 cm(-1)) is located above of the D-5(0) (Eu3+) and D-5(4) (Tb3+) emitting levels. The experimental intensity parameters ohm(lambda) (lambda : 2 and 4) for the Eu3+ NTA complex were calculated, and the results are discussed. The Gd3+ -NTA complex exhibits a high-intensity emission band in the UV region (32 000 cm(-1)) assigned to the P-6(7/2) -> S-8(7/2) intraconfigurational transition.
palavras-chave
INTRAMOLECULAR ENERGY-TRANSFER; SPECTROSCOPIC PROPERTIES; LANTHANIDE; LUMINESCENCE; IONS; PHOSPHORS; EUROPIUM; SPECTRA; DEVICES; ACID
categoria
Chemistry
autores
Silva, IGN; Brito, HF; Souza, ER; Mustafa, D; Felinto, MCFC; Carlos, LD; Malta, OL
nossos autores
Luís Carlos
Professor Catedráticoagradecimentos
We are grateful for financial support from the Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq, Brazil), Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP, Brazil), Instituto Nacional de Ciencia e Tecnologia de Nanotecnologia para Marcadores Integrados (inct-INAMI, Brazil), Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES, Brazil) and Fundacao para a Ciencia e a Tecnologia under contract Pest-C/CTM/LA0011/2013. L. D. C. thanks CAPES for a fellowship within the Nanobiotec network