Síntese e caracterização de estruturas supramoleculares organizadas a partir de sistemas de paládio(II)/ácidos dicarboxílicos/ligantes lineares nitrogenados
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Data
2008-02-26
Autores
Fernandes, Rafael Lilli [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Este trabalho contempla a preparação e a caracterização estrutural, térmica e morfológica de novas espécies de paládio (II), discretas e multidimensionais, usando o complexo [PdCl2(CH3CN)2] como material de partida. Visando obter sólidos de coordenação porosos, foram utilizados como ligantes os espaçadores lineares nitrogenados 4,4’-bipiridina (4,4’-bipy), trans–1,2-bis(4-piridil)etileno (bpe) e pirazina (pz), além dos grupos dicarboxilatos oxalato e fumarato. Foram obtidas duas séries de compostos, [Pd2(μ-ox)(ox)(L)]n (1-3) e [Pd(μ-fum)(μ-L)]n.nH2O (4-6) (ox = oxalato; fum = fumarato; L = 4,4’-bipy, bpe, pz). As hipóteses estruturais mais prováveis para essas metalosupramoléculas envolvem a formação de espécies octanucleares contendo cavidades quadradas e grades 2D retangulares, respectivamente. Curvas TG/DSC permitiram o estabelecimento da ordem de estabilidade térmica e a confirmação das estequiometrias propostas para os compostos obtidos. A microscopia eletrônica de varredura permitiu averiguar as características morfológicas das partículas dos compostos, bem como inferir a presença de poros nos mesmos. Foram realizados, então, ensaios de adsorção de nitrogênio e de porosimetria de mercúrio, onde pode ser observado que as dimensões das cavidades ou canais formados nas estruturas das supramoléculas podem ser manipuladas pela escolha adequada do tamanho ou funcionalidade do espaçador.
This work deals with the synthesis and structural, thermal and morphological characterization of novel, discrete and multidimentional, palladium(II) species using the complex [PdCl2(CH3CN)2] as starting material. In order to obtain porous coordination solids, the linear N-based spacers, 4,4’-bipyridine (4,4’-bipy), trans–1,2-bis(4- pyridil)ethylene (bpe) and pyrazine (pz), as well the dicarboxylate groups, oxalate and fumarate, were utilized as ligands. Two series of compounds were obtained, [Pd2(μ- ox)(ox)(L)]n (1-3) and [Pd(μ-fum)(μ-L)]n.nH2O (4-6) (ox = oxalate; fum = fumarate; L = 4,4’- bipy, bpe, pz). The more probable structural hypothesis for these metallosupramolecules includes the formation of octanuclear species containing square cavities and 2D retangular grids, respectively. TG/DSC curves allowed the proposition of a thermal stability order and the confirmation of the proposed stoichiometric composition for the obtained compounds. MEV micrographies permitted to investigate the morphologic characteristics of the particles of the compounds, as well to infer about the presence of the porous in these systems. Mercury porosimetry and nitrogen adsorption experiments were then carried out, in which it was possible to observe that the dimentions of the cavities or canals of the supramolecules can be manipulated by the convenient choice of the size or the functionality of the spacer.
This work deals with the synthesis and structural, thermal and morphological characterization of novel, discrete and multidimentional, palladium(II) species using the complex [PdCl2(CH3CN)2] as starting material. In order to obtain porous coordination solids, the linear N-based spacers, 4,4’-bipyridine (4,4’-bipy), trans–1,2-bis(4- pyridil)ethylene (bpe) and pyrazine (pz), as well the dicarboxylate groups, oxalate and fumarate, were utilized as ligands. Two series of compounds were obtained, [Pd2(μ- ox)(ox)(L)]n (1-3) and [Pd(μ-fum)(μ-L)]n.nH2O (4-6) (ox = oxalate; fum = fumarate; L = 4,4’- bipy, bpe, pz). The more probable structural hypothesis for these metallosupramolecules includes the formation of octanuclear species containing square cavities and 2D retangular grids, respectively. TG/DSC curves allowed the proposition of a thermal stability order and the confirmation of the proposed stoichiometric composition for the obtained compounds. MEV micrographies permitted to investigate the morphologic characteristics of the particles of the compounds, as well to infer about the presence of the porous in these systems. Mercury porosimetry and nitrogen adsorption experiments were then carried out, in which it was possible to observe that the dimentions of the cavities or canals of the supramolecules can be manipulated by the convenient choice of the size or the functionality of the spacer.
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Palavras-chave
Química inorgânica, Química supramolecular, Palladius, Rutilius Taurus Aemilianus
Como citar
FERNANDES, Rafael Lilli. Síntese e caracterização de estruturas supramoleculares organizadas a partir de sistemas de paládio (II)/ácidos dicarboxílicos/ligantes lineares nitrogenados. 2008. 86 f. Dissertação (mestrado) - Universidade Estadual Paulista, Instituto de Química., 2008.