Lanthanide
Mostrando 25-36 de 102 artigos, teses e dissertações.
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25. AvaliaÃÃo espectroscÃpica da substituiÃÃo sistemÃtica de molÃculas de Ãgua coordenadas por ligantes β-dicetonas em complexos com Ãons lantanÃdeos
In this work, lanthanide complexes with β-diketones (2,4-pentanedione and trifluoroacetylacetone) and β-keto esters (etil 4,4,4,-trifluoro-2,4- pentanedione) ligands have been synthesized. The complexes showed general formulas: [Ln(acac)(H2O)6]Cl2, [Ln(acac)2(H2O)4]Cl, [Ln(tfa)(H2O)6]Cl2, [Ln(tfa)2(H2O)4]Cl e [Ln(eta)2(H2O)4]Cl. The compounds were
Publicado em: 2008
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26. Estudos conformacionais em compostos contendo íons lantanídeos
Lanthanide macrocyclic complexes, especially containing Gd(III) ions, are largely used as contrast agents in the medical diagnostic technique named Magnetic Resonance Imaging (MRI). Theoretical investigation of these compounds by molecular modeling methods is an emerging research area today. In this work we have performed a conformational study of the follow
Publicado em: 2008
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27. Redes de coordenaÃÃo com Ãons lantanÃdeos: sÃntese, caracterizaÃÃo e estudo espectroscÃpio
This work shows the synthesis of new metalorganic frameworks containing Eu3+ and Gd3+ ions, using 1,3,5,-benzenetrisbenzoic acid (H3BTB) as ligand. The H3BTB was synthesized in two steps and characterized by elemental analysis, infrared spectroscopy and nuclear magnetic resonance 1H and 13C; the obtained results confirm all literature dataâs. Networks of co
Publicado em: 2008
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28. Study of the influence of synthesis conditions on the size particles of polystyrene and poly(methylmethacrylate) with lanthanide complexes / Estudo da influÃncia das condiÃÃes de sÃntese no tamanho de partÃcula de lÃtices de poliestireno e poli(metilmetacrilato) e incorporaÃÃo de complexos de lantanÃdeos
A polimerizaÃÃo em emulsÃo à um processo utilizado na produÃÃo de lÃtex sintÃticos. A tÃcnica à muito utilizada, pois permite a produÃÃo de grande variedade de polÃmeros, permitindo o controle das propriedades fÃsico-quÃmicas e morfolÃgicas do lÃtex. A concentraÃÃo do monÃmero, iniciador, fluxo de nitrogÃnio, velocidade de agitaÃÃo e a
Publicado em: 2008
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29. Intercalação de íons lantanídeos e de poli(óxido de etileno) assistida por tensoativo na matriz hospedeira VOPO4.2H2O / Intercalation of ions Lanthanides and Poly (ethylene oxide) assisted by surfactant in host matrix of VOPO4.2H2O
Vanadium compounds are intensively studied due to their electrochemical, catalytic, magnetic and biological properties. In this work, our goal was to investigate the VOPO4.2H2O (vanadyl phosphate), which has a lamellar structure formed by VOPO4 sheets interconnected by weak interactions. Taking advantage of this structure, it is possible to synthesize severa
Publicado em: 2008
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30. Desenvolvimento de um biossensor de peróxido de hidrogênio de baixo custo baseado na emissão do európio III. / Development of a low cost hydrogen peroxide biosensor based on europium (III).
In this work was studied the optical properties of Europium-Tetracycline complex (EuTc), determining the best conditions to obtain an efficient complex formation. Optical parameters as absorption, emission, lifetime and refractive index were obtained. Variation of europium complexes concentration, temperature, optimal pH and solutions time reaction were anal
Publicado em: 2008
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31. Synthesis and characterization of Eu3+ and Er3+ doped SiO2-ZrO2 based transparent glass ceramic nanocomposites via sol-gel process / Síntese e caracterização de nanocompósitos vitrocerâmicos transparentes a base de SiO2-ZrO2 dopados com íons Eu3+ e Er3+ via processo sol-gel
The preparation of transparent glass-ceramic based on the SiO2-ZrO2 doped with Eu3+ and Er3+ ions by the sol-gel methodology was the aim of this work. The structural and optical properties of the systems as a function of the time and temperature of annealing and also zirconium concentration are presented. The sol was prepared in acid solution and left in res
Publicado em: 2008
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32. Ãteres coroa com Ãons lantanÃdeos: de compostos de coordenaÃÃo a novos materiais nanoestruturados de sÃlica
Com o objetivo de desenvolver novos materiais e ligantes, baseados em Ãteres coroa, capazes de coordenarem um ou mais Ãons lantanÃdeos, o presente trabalho mostra a sÃntese de compostos de coordenaÃÃo mono e binucleares, livres ou ligados Ãs matrizes de sÃlica. As caracterizaÃÃes foram realizadas via anÃlise elementar, anÃlise termogravimÃtrica,
Publicado em: 2008
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33. Parâmetros operacionais no processamento de zeólitas desativadas por fusão com KHSO4
This work presents a study on the determination of the optimal experimental conditions for processing spent commercial zeolites in order to recover lanthanide elements and eventually other elements. The process is based on the fusion of the sample with potassium hydrogenosulfate (KHSO4). Three experimental parameters were studied: temperature, reaction time
Química Nova. Publicado em: 2007-04
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34. Modelo Sparkle: novos avanÃos para o estudo quÃmico-quÃntico de complexos de lantanÃdeos
Since 1994, the Sparkle Model for Lanthanide Complexes has been used for the calculation of ground state geometries of only Eu(III) complexes. In the present thesis, we evolved the Sparkle Model and advanced Sparkle/AM1 and Sparkle/PM3: new paradigms for semiempirical quantum chemical calculations on lanthanide complexes. Parameterizations for all fifteen tr
Publicado em: 2007
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35. Estudo do comportamento térmico e da luminescência de filmes de quitosana com os íons Eu3+ e Tb3+
Films of chitosan with trivalent lanthanides ions Eu3+ and Tb3+ were respectively prepared in the ratio of 3:1 m/m (chitosan: lanthanide) and 6:1 m/m (chitosan: lanthanide). There were no formations of films in a ratio of 1:1 m/m (chitosan: lanthanides). The films of chitosan with the Tb3+ ion have the same transparent appearance than the pure chitosan films
Publicado em: 2007
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36. SYNTHESIS, CHARACTERIZATION AND STUDIES SPECTROSCOPY OF COORDINATION NETWORKS HYBRID CONTAINING LANTHANIDES. / SÍNTESE, CARACTERIZAÇÃO E ESTUDOS ESPECTROSCÓPICOS DE REDES DE COORDENAÇÃO HÍBRIDAS CONTENDO LANTANÍDEOS.
In this work is presented the hydrothermal synthesis, the structural studies and spectroscopic properties of three coordination polymers based on lanthanides ions (Eu3+, Tb3+ and Gd3+) and DPA as ligand (DPA= 2,6- dipicolinate). Structural study of [Eu(DPA)(HDPA)(H2O)2.4H2O] displayed the presence of self-assembled dimeric and hexameric water clusters fit in
Publicado em: 2007