resumo
A series of europium Eu- and La-doped complexes with two different crystal structures, namely, EuxLa1-x(phen)(2)(NO3)(3) [phen = 1,10-phenanthroline, x = 1.0 (1), 0.88 (2), 0.73 (3), and 0.52 (4)] and {[EuxLa1-x(phen)(2)(H2O)(2)(NO3)(2)](NO3)2(phen)(H2O)} [x = 0.28 (5) and 0.0 (6)], were synthesized in aqueous solution by using different Eu/La ratios.The complexes were characterized by single-crystal and powder X-ray diffraction, Fourier transform infrared spectroscopy, elemental analysis, thermogravimetry, and scanning electron microscopy. Compounds 1-4 and 5, 6 were obtained for Eu/La molar ratios higher than 5:5 and smaller than 3:7, respectively. The photoluminescence properties of these compounds depend on the crystal structure, which is determined by the Eu/La reactant ratio. Complexes 1-4 exhibit a quantum efficiency ( = 55%) and quantum yield (q = 31%) higher than 5 ( = 23% and q = 6%). The photophysical properties assessed by using the LUMPAC software are in good accord with the experimental values, particularly, the calculated (26%) and measured emission quantum yields (31%; excitation at the ligands at 255 nm).
palavras-chave
METAL-ORGANIC FRAMEWORK; EMISSION QUANTUM YIELD; RARE-EARTH IONS; INTRAMOLECULAR ENERGY-TRANSFER; LANTHANIDE COMPLEXES; PHOTOLUMINESCENCE PROPERTIES; COORDINATION-COMPOUNDS; DIFFERENTIAL-OVERLAP; INTERMEDIATE NEGLECT; THEORETICAL APPROACH
categoria
Chemistry
autores
Yang, TH; Fu, LS; Ferreira, RAS; Nolasco, MM; Rocha, J; Carlos, LD; Shi, FN
nossos autores
Fa-Nian Shi
Investigador
João Rocha
Prof. Catedrático
Lianshe Fu
Investigador Auxiliar
Luís Carlos
Professor Catedrático
Maria Rute de Amorim e Sá Ferreira André
Professor Catedrático
Mariela Martins Nolasco
Investigador Auxiliar
Tinghai Yang
Bolseiro de pós-DoutoramentoGrupos
G1 - Materiais Porosos e Nanossistemas
G2 - Materiais Fotónicos, Eletrónicos e Magnéticos
G6 - Materiais Virtuais e Inteligência Artificial
Projectos
CICECO - Aveiro Institute of Materials (UID/CTM/50011/2013)
Harvesting the energy of the sun for a sustainable future (CENTRO-07-ST24-FEDER-002032)
agradecimentos
This work was financed by the Portuguese Fundacao do Ministerio de Ciencia e Tecnologia (FCT) (PTDC/CTM-NAN/119994/2010, grant to F.-N. S. and SFRH/BPD/74582/2010, grant to T.-H. Y.) and through the Aveiro Institute of Materials, CICECO project number UID/CTM/50011/2013, and when applicable co-financed by the Fundo Europeu de Desenvolvimento Regional (FEDER) under the PT2020 Partnership Agreement. T.-H. Y. acknowledges support by the NSF of Jiangsu Province (BK20140244), by the the project sponsored by the Scientific Research Foundation for Returned Overseas Chinese Scholars of the State Education Ministry, by the NSF for Universities in Jiangsu Province (13KJB150013), by the Science and Technology Bureau of Changzhou City (CJ20140031) and by the Jiangsu University of Technology (KYY13035). M. M. N. is thankful for a post-doctoral scholarship by the Project Mais Centro - PORC, project number CENTRO-07-ST24-FEDER-002032 (grant number BPD/UI96/3340/2014).