Estudo dos difenilfosfinatos de lantânio ativados por cério, európio e térbio emissores luminescentes multicores
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2008-01-22
Autores
Abreu, Edson Martins de [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Vários estudos do ponto de vista experimental sobre complexos lantanídicos revelaram características, como estabilidade térmica em torno de 500 ºC e inércia química, que eram só observadas em sólidos inorgânicos. A partir destas características vem sendo desenvolvido modelos teóricos para explicar qual fenômeno físico ou químico estão envolvidos nesta classe de compostos de coordenação. A luminescência também revela comportamentos interessantes como a eficiência da transferência de energia da parte orgânica para os íons lantanídeos. Portanto, os objetivos deste trabalho foram a preparação, a caracterização e o estudo da luminescência de compostos de difenilfosfinatos de lantânio ativados pelos íons cério, európio e térbio trivalentes. Os seguintes compostos foram preparados i) La1-xEux[O2P(Ph)2]3 ; ii) La1-xTbx[O2P(Ph)2]3; iii) La1-(x+y)CexEuy[O2P(Ph)2]3 ;iv) La1-(x+y+z) CexEuyTbz[O2P(Ph)2]3, onde x varia de 0,002 a 0,50, y varia de 0,01 a 0,10 e z de 0,01 a 0,10. Os difenilfosfinatos de lantanídeos formam pós brancos, cristalinos, insolúveis nas Condições Normais de Temperatura e Pressão e são química e termicamente estáveis. Algumas diferenças entre o ácido difenilfosfínico e os compostos sintetizados foram reveladas através da espectroscopia vibracional na região de absorção do infravermelho: i) nos espectros de infravermelho, o desaparecimento do modo vibracional P-OH e os deslocamentos da absorção das ligações P-O para regiões de energias menores evidenciaram a complexação. Pela análise dos difratogramas de raios-X .e resultados de simulação foram propostos os sistemas cristalinos hexagonal e cúbico. Os complexos sintetizados quando excitados através da banda do ligante apresentam emissões fortes na região do visível que dependem da concentração dos íons ativadores...
Several studies of the experimental point of view on lanthanides complexes revealed characteristics, such as thermal stability of around 500 ° C and chemical inert, which were only observed in solid inorganic. From these characteristics has been developed theoretical models to explain which physical or chemical phenomena are involved in this class of compounds of coordination. The luminescence also reveals interesting behaviors such as energy transfer efficiency from the organic ligand for the lanthanide ions. Therefore, the aims of this work were the preparation, the characterization, and the luminescence study of compounds of cerium, europium, and terbium ions activated by lanthanide diphenylphosphinates. The following compounds were prepared: i) La1-xEux[O2P(Ph)2]3 ; ii) La1-xTbx[O2P(Ph)2]3; iii) La1-(x+y)CexEuy[O2P(Ph)2]3 ; v) La1-(x+y+z) CexEuyTbz[O2P(Ph)2]3, where x ranges from 0.002 to 0.50, y varies from 0.01 to 0.10, and z from 0.01 to 0.10. The lanthanide diphenylphosphinates give rise to white crystalline powders, usually insoluble under standard conditions of temperature and pressure, showing thermal and chemical stability. Some differences between the diphenylphosphinic acid and the synthesized compounds were unveiled InfraRed Spectroscopy: i) in the IR spectra the disappearance of the P-OH vibrational mode and the red shift observed for the P-O bond evidenced the complex formation. The hexagonal and cubic crystalline systems were proposed by X-ray diffratometry and simulation results. When excited at the ligand absorption region, the complexes gave rise to a strong emission at the visible region, which was dependent on the concentration of activators. The photoluminescence spectra of La1-xEux[O2P(Ph)2]3 evidenced variations in the relationship of intensities for the Eu (III) ion emission bands, which indicate the presence of two or more symmetry sites, being one of them endowed...(Completo abstract click electronic access below)
Several studies of the experimental point of view on lanthanides complexes revealed characteristics, such as thermal stability of around 500 ° C and chemical inert, which were only observed in solid inorganic. From these characteristics has been developed theoretical models to explain which physical or chemical phenomena are involved in this class of compounds of coordination. The luminescence also reveals interesting behaviors such as energy transfer efficiency from the organic ligand for the lanthanide ions. Therefore, the aims of this work were the preparation, the characterization, and the luminescence study of compounds of cerium, europium, and terbium ions activated by lanthanide diphenylphosphinates. The following compounds were prepared: i) La1-xEux[O2P(Ph)2]3 ; ii) La1-xTbx[O2P(Ph)2]3; iii) La1-(x+y)CexEuy[O2P(Ph)2]3 ; v) La1-(x+y+z) CexEuyTbz[O2P(Ph)2]3, where x ranges from 0.002 to 0.50, y varies from 0.01 to 0.10, and z from 0.01 to 0.10. The lanthanide diphenylphosphinates give rise to white crystalline powders, usually insoluble under standard conditions of temperature and pressure, showing thermal and chemical stability. Some differences between the diphenylphosphinic acid and the synthesized compounds were unveiled InfraRed Spectroscopy: i) in the IR spectra the disappearance of the P-OH vibrational mode and the red shift observed for the P-O bond evidenced the complex formation. The hexagonal and cubic crystalline systems were proposed by X-ray diffratometry and simulation results. When excited at the ligand absorption region, the complexes gave rise to a strong emission at the visible region, which was dependent on the concentration of activators. The photoluminescence spectra of La1-xEux[O2P(Ph)2]3 evidenced variations in the relationship of intensities for the Eu (III) ion emission bands, which indicate the presence of two or more symmetry sites, being one of them endowed...(Completo abstract click electronic access below)
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Palavras-chave
Química inorgânica, Luminescencia, Transferência de energia, Polímeros de coordenação
Como citar
ABREU, Edson Martins de. Estudo dos difenilfosfinatos de lantânio ativados por cério, európio e térbio emissores luminescentes multicores. 2008. 138 f. Tese (doutorado) - Universidade Estadual Paulista, Instituto de Química, 2008.