Novos complexos binucleares de cobre de relevância bioinorgânica

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas.Novos complexos binucleares de cobre(II) foram sintetizados e caracterizados: [Cu2(H2bbppnol)(m-CH3COO)(H2O)2]Cl2.2H2O (1), [Cu2(H2bbppnol)(m-CH3COO)(m-ClO4)]ClO4·H2O·EtOAc (2), [Cu2(Hbbppnol)(H2O)4](ClO4)2×2CH3OH (3), [Cu2(Hbtppnol)(m-CH3COO)](ClO4)2 (4), [Cu2(tppnol)(m-CH3COO)](ClO4)2 (5) [Cu2(Hbtppnol)OH](ClO4)2 (6) e [Cu2(Hbtppnol)(m-(NO2-C6H4)PO4)](ClO4) (7). Os complexos (1) e (4) são os primeiros a apresentar a coordenação axial de grupos fenóis protonados a centros binucleares de cobre(II) servindo como modelos estruturais para o intermediário enzima-substrato no mecanismo de hidroxilação de monofenóis promovida pela tirosinase. Os bons resultados obtidos na modelagem estrutural conduziu-nos ao estudo dos complexos frente a substratos adequados. Os complexos foram testados e mostraram atividade frente ao substrato 3,5-di-terc-butilcatecol numa reação modelo para a atividade de catecolase desempenhada pelas enzimas tirosinase e catecol oxidase, e frente ao substrato bis(2,4-dinitrofenil)fosfato numa reação modelo para hidrolases

"Metallic Nanoparticles for Biomass Conversion to Highly Valued Chemicals"

International audienc

High performance magnetic separation of gold nanoparticles for catalytic oxidation of alcohols

We present the magnetic separation approach to facilitate the recovery of gold nanoparticle (AuNP) catalysts. The use of magnetically recoverable supports for the immobilization of AuNPs instead of traditional oxides, polymers or carbon based solids guarantees facile, clean, fast and efficient separation of the catalyst at the end of the reaction cycle. Magnetic separation can be considered an environmentally benign separation approach, since it minimizes the use of auxiliary substances and energy for achieving catalyst recovery. The catalyst preparation is based on the immobilization of Au(3+) on the surface of core-shell silica-coated magnetite nanoparticles, followed by metal reduction using two different methods. AuNPs were prepared by thermal reduction in air and by hydrogen reduction at mild temperature. Interestingly, the mean particle size of the supported AuNPs was similar (ca. 5.9 nm), but the polydispersity of the samples is quite different. The catalytic activity of both catalysts in the aerobic oxidation of alcohols was investigated and a distinct selectivity for benzyl alcohol oxidation was observed.FAPESPCNP

Catalytic hydrodechlorination of chlorobenzene over supported palladium catalyst in buffered medium

The catalytic hydrodechlorination (HDC) reaction, which is an attractive abatement process for chlorinated organic wastes, was studied over a magnetically recoverable supported Pd(0) catalyst. We investigated the most favorable reaction conditions under which to obtain the highest substrate conversion rates while preserving the catalyst properties and morphology. Sodium hydroxide, triethylamine and buffered solutions were used as proton scavengers in the HDC of chlorobenzene under mild conditions. It was observed that sodium hydroxide caused corrosion of the silica support, triethylamine in 2-propanol preserved the morphology of the catalyst which could be recycled for up to five successive H DC reactions, and aqueous buffer solutions preserved the catalyst morphology and the catalytic activity for up to four successive HDC reactions. The use of buffer solutions to neutralize the HCl formed during the HDC reaction is an interesting, less aggressive, alternative approach to HDC reactions. (C) 2010 Elsevier B.V. All rights reserved.FAPESPFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)CNPqConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Clean preparation of methyl esters in one-step oxidative esterification of primary alcohols catalyzed by supported gold nanoparticles

Methyl esters were prepared by the clean, one-step catalytic esterification of primary alcohols using molecular oxygen as a green oxidant and a newly developed SiO(2)-supported gold nanoparticle catalyst. The catalyst was highly active and selective in a broad range of pressure and temperature. At 3 atm O(2) and 130 degrees C benzyl alcohol was converted to methyl benzoate with 100% conversion and 100% selectivity in 4 h of reaction. This catalytic process is much ""greener"" than the conventional reaction routes because it avoids the use of stoichiometric environmentally unfriendly oxidants, usually required for alcohol oxidation, and the use of strong acids or excess of reactants or constant removal of products required to shift the equilibrium to the desired esterification product.FAPESPCNP

Selective oxidation of glucose to glucuronic acid by cesium-promoted gold nanoparticle catalyst

International audienc

Interação de tetracarboxilatos de di-rodio II com papaina : estudo cinético e termodinâmico

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Interação de tetracarboxilatos de di-rodio II com papaina : estudo cinético e termodinâmico

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