Híbridos orgânicos-inogânicos aminosilano-ácido ricinoleico
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2009-08-08
Autores
Arruda, Kíria Serranegra de [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Novos híbridos orgânicos-inorgânicos, chamados de maneira geral de amidosis foram preparados a partir de ácido ricinoleico (AR) e 3-aminopropiltrietoxisilano (APTES) em duas razões estequiométricas APTES:AR diferentes (1:1 e 1:0,5). As amostras foram preparadas em tetrahidrofurano (THF) sob refluxo e caracterizadas por espectroscopia de absorção na região do infravermelho (FTIR) e ressonância magnética nuclear (RMN) de 13C, 1H e 29Si. Com essas análises foi possível confirmar a formação da ligação covalente amida entre as partes orgânica e inorgânica dos precursores. As bandas características (amida I e amida II) foram observadas nos espectros FTIR para as duas razões estequiométricas e medidas de RMN bi-dimensionais confirmam o sucesso da síntese. Híbridos amidosis luminescentes foram obtidos utilizando-se como precursores cloreto de európio ou o complexo [Eu(tta)3(H2O)2] (tta- tenoiltrifluoroacetonato). Observou-se a contribuição de duas espécies principais para a luminescência que cobre toda a região do visível, uma banda larga referente à matriz e bandas finas características do íon Eu3+. A presença do ligante tta aumenta a absorção de luz no UV através do conhecido efeito antena. De maneira interessante notou-se um aumento da intensidade luminosa de emissão com adição de excesso de ligante ao meio sugerindo um mecanismo de excitação de esfera externa. Além disso, para amostras contendo excesso de aminosilano em relação ao ácido observou-se a decomposição do ligante tta provavelmente devido ao pH igual a nove do meio reacional.
New organic-inorganic hybrids, generally classified as amidosils, were prepared from ricinoleic acid (AR) and 3-aminopropyltriethoxisilane (APTES) by using two stoichiometric ratios APTES:AR (1:1 and 1:0.5). Samples were prepared under reflux in tetrahydrofurane (THF) and were characterized by infrared absorption (FTIR) and 13C, 29Si and 1H Nuclear Magnetic Ressonance (NMR) spectroscopies. The resulting amide group was successfully identified by FTIR (amide I and amide II bands) and bi-dimensional NMR analysis. Luminescent amidosil hybrids were obtained by the addition of different Eu3+ compounds, i.e., europium chloride and the complex [Eu(tta)3(H2O)2] (tta stands for thenoyltrifluoroacetonate). Strong luminescence was observed with the contribution of mainly two components, a broad band from the hybrid matrix and the characteristic narrow lines from Eu3+. The tta organic ligand contributes to the luminescence intensity through the well known antenna effect. The addition of excess tta (completely out of a stoichiometric ratio) leads to higher light output suggesting an interesting outer sphere excitation mechanism. For samples prepared with the stoichiometric ratio APTES:AR 1:0.5 decomposition of the tta ligand was clearly observed, most probably due to the basic pH observed in the reactional medium.
New organic-inorganic hybrids, generally classified as amidosils, were prepared from ricinoleic acid (AR) and 3-aminopropyltriethoxisilane (APTES) by using two stoichiometric ratios APTES:AR (1:1 and 1:0.5). Samples were prepared under reflux in tetrahydrofurane (THF) and were characterized by infrared absorption (FTIR) and 13C, 29Si and 1H Nuclear Magnetic Ressonance (NMR) spectroscopies. The resulting amide group was successfully identified by FTIR (amide I and amide II bands) and bi-dimensional NMR analysis. Luminescent amidosil hybrids were obtained by the addition of different Eu3+ compounds, i.e., europium chloride and the complex [Eu(tta)3(H2O)2] (tta stands for thenoyltrifluoroacetonate). Strong luminescence was observed with the contribution of mainly two components, a broad band from the hybrid matrix and the characteristic narrow lines from Eu3+. The tta organic ligand contributes to the luminescence intensity through the well known antenna effect. The addition of excess tta (completely out of a stoichiometric ratio) leads to higher light output suggesting an interesting outer sphere excitation mechanism. For samples prepared with the stoichiometric ratio APTES:AR 1:0.5 decomposition of the tta ligand was clearly observed, most probably due to the basic pH observed in the reactional medium.
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Química inorgânica, Fotoluminescencia, Europio, Inorganic chemistry
Como citar
ARRUDA, Kíria Serranegra de. Híbridos orgânicos-inogânicos aminosilano-ácido ricinoleico. 2009. 71 f. Dissertação (mestrado) - Universidade Estadual Paulista, Instituto de Química, 2009.