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Doctoral Thesis
DOI
10.11606/T.46.2018.tde-30112018-111457
Document
Author
Full name
Sergio Dovidauskas
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2001
Supervisor
Committee
Toma, Henrique Eisi (President)
Azzellini, Gianluca Camillo
Batista, Alzir Azevedo
Ferreira, Ana Maria da Costa
Iamamoto, Yassuko
Title in Portuguese
Química supramolecular de porfirino-clusters
Keywords in Portuguese
Bioquímica inorgânica
Catálise
Catalysis
Metalloporphyrins
Porphyrin-clusters
Química inorgânica
Sensors
Trinuclear ruthenium clusters
Abstract in Portuguese
Três novas supermoléculas, aqui designadas por ZnTCP4+, MnTCP5+ e CoTCP5+, foram obtidas pela coordenação de quatro acetatos trinucleares assimétricos de rutênio, [Ru3O(CH3CO2)6(py)2(CH3OH)]+, aos resíduos piridínicos de meso-tetra(4-piridil)porfirinato de ZnII, MnIII e CoIII, respectivamente (ZnTPyP, MnTPyP e CoTPyP). A caracterização destas supermoléculas foi efetuada por espectroscopia de ressonância magnética nuclear e espectroscopia eletrônica. O comportamento eletroquímico foi investigado por voltametria cíclica e espectroeletroquímica. Os efeitos dos acetatos trinucleares periféricos sobre a reatividade do núcleo porfirínico foram analisados: (i) para ZnTCP4+, além da supressão da luminescência, verificou-se que as constantes de coordenação axial determinadas em diclorometano para piridina e imidazol, quando comparadas às respectivas constantes de ZnTPyP e de meso-tetra(fenil)porfirinato de zinco, indicaram um aumento significativo da acidez de Lewis do íon Zn2+; (ii) MnTCP5+ revelou-se um catalisador mais seletivo que MnTPyP na oxidação de ciclohexano em fase homogênea, utilizando-se iodosilbenzeno como doador de oxigênio; (iii) os eletrodos modificados por filmes de CoTCP5+ apresentaram uma eficiente atividade catalítica na redução tetra-eletrônica de dioxigênio a água, comportamento que contrasta com o descrito na literatura para filmes de CoTPyP. A redução tetra-eletrônica de dioxigênio catalisada pelos filmes de CoTCP5+ foi confirmada por voltametria cíclica, voltametria de eletrodo disco rotatório e voltametria de eletrodo de anel e disco rotatórios.
Title in English
Supramolecular chemistry of porphyrin-clusters
Keywords in English
Catalysis
Inorganic chemistry
Metalloporphyrins
Porphyrin-clusters
Sensors
Trinuclear ruthenium clusters
Abstract in English
Three novel supermolecules designated as ZnTCP4+, MnTCP5+, and CoTCP5+ were obtained by coordination of four assymetric trinuclear ruthenium acetate species, [Ru3O(CH3CO2)6(py)2(CH3OH)]+ to pyridine residues of ZnII -, MnIII -, and CoIIITPyP, respectively (TPyP = meso-tetra(4-pyridil)porphyrinate). These new compounds were characterized by nuclear magnetic resonance spectroscopy and electronic spectroscopy. The electrochemical behavior was investigated by cyclic voltammetry, and spectroelectrochemistry. The influence of the peripheral trinuclear acetate on the porphyrin core reactivity was assayed: (i) for ZnTCP4+, besides the luminescence quenching, the calculated equilibrium constants for axial coordination of pyridine and imidazole in dichloromethane demonstrated a significant increase in the Zn2+ Lewis acidity in comparison with the respective constants from ZnTPyP and zinc meso-tetra(phenyl)porphyrinate; (ii) MnTCP5+ exhibited improved selectivity as catalyst for ciclohexane oxidation (homogeneous phase) in comparison with MnTPyP using iodosylbenzene as oxygen donor; (iii) modified electrodes by CoTCP5+ films showed an outstanding catalytic activity in the tetraelectronic reduction of dioxygen to water, in contrast with CoTPyP films described in the literature; the dioxygen tetraelectronic reduction was confirmed by cyclic voltammetry, rotating disk electrode voltammetry, and rotating ring and disk electrode voltammetry.
 
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Publishing Date
2018-11-30
 
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