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Master's Dissertation
DOI
10.11606/D.54.1982.tde-16042014-172123
Document
Author
Full name
Márcio Francisco Colombo
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 1982
Supervisor
Committee
Massabni, Antonio Carlos
Panepucci, Horacio Carlos
Tabak, Marcel
Title in Portuguese
Investigação dos complexos de Cu(II) com tris-(hidroximetil) aminometano formados em solução aquosa por ressonância paramagnética eletrônica e absorção ótica
Keywords in Portuguese
Absorção ótica
Cu(II)
RPE
Tris-hidroximetil-aminometano
Abstract in Portuguese
Ressonância Paramagnética Eletrônica (RPE) e Absorção Ótica Eletrônica foram utilizadas para estudar-se os complexos de Cobre (II) com tris-hidroximetil aminometano em solução. A análise dos parâmetros de RPE e óticos medidos na solução a diversos pHs foi feita tendo-se à mão as curvas de formação dos complexos. Estas curvas foram construídas em função do pH da solução, usando os dados de equilíbrio químico publicado por K. S. Bai e Martell (J. Inorg. Nucl. Chem. 31 (1969) 1697-1707), numa faixa de concentração de tris na qual este reagente é usando como tampão em estudos biológicos e químicos. Determinou-se cinco conjunto de parâmetros de RPE (go, ao, a11 e A11, correspondentes a diferentes complexos de íon metálico. Cada um desses espectros é encontrado em determinados intervalos de pH, sendo possível associá-los aos complexos previstos nas curvas de formação. A maior estabilidade dos complexos que se formam a pHs mais altos segundo as constantes de equilíbrio é evidenciada pelos valores e go isotrópico (RPE) menores pelos desdobramentos hiperfino isotrópico ao (RPE) e de campo cristalino (ótica) maiores do que os encontrados nas soluções menos alcalinas. A formação do complexo quelato neutro a pH alcalino foi observada, e obteve-se seu tensor g, das medidas do cristal simples. Este tensor encontra-se em bom acordo com o valor de g isotrópico determinado em solução (go=1/3(gxx+gyy+gzz)). Existe evidência de que este complexo seja pentacoordenado). Observou-se similaridade entre os parâmetros para os complexos coordenados por: 2N e 1N+1 0‾ 3N e 2N+1 0‾ ; 4N e 2N+2 0‾. Isto leva à conclusão de que do ponto de vista energético a coordenação de nitrogênio Cu2+ e a coordenação do oxigênio negativo ao Cu2+ nestes complexos são equivalentes, pelo menos dentro de nossa resolução experimental.
Title in English
Investigation of Cu(II) complexes with tris-hydroxymethyl-amino-methane formed in aqueous solution: EPR and optical absorption
Keywords in English
Cu(II)
EPR
Optical absorption
Tris-hydroxymethyl-aminomethane
Abstract in English
Electron Paramagnetic Ressonance (EPR) and optical visible spectroscopies were used to study the complexes of Cu (II) íon with tris-hydroxymethylamino methane (tris) in solution. Analyses of EPR and optical parameters measured in solution were made using the calculated formation curvesof the complexes. These formation curves were calculated as function of the solution pH, on the basis of the equilibrium constants published by K.S. Bai and Martell (J. Inorg.Nucl. Chem. 31 (1969)-1967-1707), for a concentration of this normally employed in a buffer in biochemical studies. Five sets of EPR parameters ((go, ao, a11 e A11) were determined corresponding to different metal complexes. Each det is found in a characteristic pH range and it was possible to make a correlation of these complexes with the appear in the formation curve plot. The greater stability of the complexes in the high pH range is indicated by the values of go, wich are smaller and the values of the hyperfine splittings ao and the crystal field splittings (from optical measurements) which are greater tahn at the less alcaline solutions. The formation of the neural chelate complexa t alcaline pH was observed, and its g-factors were obtained from measurements with the single crystal. These g-factors agree very well with the solution value (go=1/3(gxx+gyy+gzz)) and the orthorombic symmetriy is obtained. Evidence is present that this complex is penta-coordinated. It was observed a similarity between the EPR parameters for the complexes coordinated by: : 2N e 1N+1 0‾ 3N e 2N+1 0‾ ; 4N e 2N+2 0‾. This lead us the conclusion that from the energetical point of view the coordination of Cu2+ to nitrogen or to negative oxigen in these cases are equivalent, at or our resolution is not sufficent to differentiate between them.
 
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Publishing Date
2014-04-22
 
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