Binuclear CuII complexes as catalysts for hydrocarbon and catechol oxidation reactions with hydrogen peroxide and molecular oxygen

Martins, Luciana R.; Souza, Elizabeth T.; Fernandez, Tatiana L.; Souza, Bernardo de; Rachinski, Sílvio; Pinheiro, Carlos B.; Faria, Roberto B.; Casellato, Annelise; Machado, Sérgio P.; Mangrich, Antônio S.; Scarpellini, Marciela

doi:10.1590/s0103-50532010000700009

Cited by 22 publications

(14 citation statements)

References 51 publications

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“…These results are comparable with those previously reported for a V IV O complex in a N 3 O 3 environment and for a dinuclear Cu II complex. 16,18 Despite the low overall conversion presented by complexes 1 and 2, it is higher than the corresponding uncatalyzed reactions which lead to less than 0.5% of overall conversion and selectivity to cyclohexylhydroperoxide or cyclohexyl-tert-butylhidroperoxide. Considering that these experiments were carried out at 1 atm pressure, room ), auxiliary = platinum wire and ferrocene as internal reference.…”

Section: Catalytic Oxidation Of Cyclohexanementioning

confidence: 99%

“…16 Thus, the development of bioinspired catalysts, which have low activation energy and require friendly oxidants, embrace important advantages from the environmental standpoint. [16][17][18] In this way, a number of model complexes for vanadium containing enzymes and other vanadium complexes had their catalytic properties evaluated towards the peroxidative oxidation of alkenes and aromatic hydrocarbons. 6,[19][20][21][22][23] In this work, we present the synthesis and characterization of two novel vanadium(V) cis-dioxo complexes of general formula [VO 2 (L)] and [VO 2 (HLox)], where HL = (3-[(bis-pyridin-2-yl-methylamino)-methyl]-2-hydroxy-5-methyl-benzaldehyde) and H 2 Lox = (3-[(bis-pyridin-2-ylmethylamino)-methyl]-2-hydroxy-5-methyl-benzaldehyde oxime), and preliminary reactivity studies on the catalytic oxidation of cyclohexane by these complexes employing H 2 O 2 or t-BuOOH as oxidants.…”

Section: Introductionmentioning

confidence: 99%

“…In fact, this same behavior has been observed before and may be one of the reasons of the overall conversion values using H 2 O 2 to be about nine times larger compared with t-BuOOH, for complex 1. 16,18,[40][41][42] However, it cannot be excluded that acetonitrile plays an important role in this process because of a competition between the solvent and the hydrocarbon by an oxidizing species, which can be generated with both oxidants. 16,43 Although the overall conversion values for both complexes are low, they showed to be selective to the intermediates cyclohexylhydroperoxide (Cy-OOH) or cyclohexyl-tert-butylhydroperoxide (Cy-OO-t-Bu), depending if the oxidant was H 2 O 2 or t-BuOOH.…”

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confidence: 99%

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Synthesis, characterization and catalytic activity of two novel cis-dioxovanadium(v) complexes: [VO2(L)] and [VO2(Hlox)]

Silva¹,

Pinheiro²,

Chacon³

et al. 2011

J. Braz. Chem. Soc.

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Dois novos complexos [VO 2 (L)] e [VO 2 (HLox)]foram sintetizados e caracterizados por espectroscopias no IV, UV-Vis e RMN, voltametria cíclica, análise elementar e difração de raios X. A síntese do ligante inédito H 2 Lox também é descrita. Os complexos 1 e 2 foram obtidos pela reação de [VO(acac) 2 ] com os respectivos ligantes HL e H 2 Lox. Alternativamente, 2 foi preparado a partir da reação de HL com [VO(acac) 2 ] na presença de hidroxilamina, e através da reação de 1 com hidroxilamina. Dados cristalográficos mostram que 1 e 2 apresentam estruturas moleculares similares, onde o centro de vanádio(V) cis-dioxo encontra-se coordenado em um ambiente octaédrico distorcido formado pelos ligantes L -e HLox -, respectivamente. A atividade catalítica destes compostos foi avaliada na oxidação do cicloexano, utilizando H 2 O 2 e t-BuOOH como oxidantes. Ambos apresentam seletividade > 70% para formação de cicloexilidroperóxido. Cálculos B3LYP/6-31G(d) foram empregados na otimização da geometria e para auxiliar na atribuição do espectro eletrônico.Two novel complexes, [VO 2 (L)] (1) and [VO 2 (HLox)] (2), were synthesized and characterized by IV, UV-Vis and NMR spectroscopy, cyclic voltammetry, elemental analysis and X-ray diffraction. The synthesis of a new ligand, H 2 Lox, is also described. Complexes 1 and 2 were obtained by the reaction of [VO(acac) 2 ] with the ligands HL and H 2 Lox, respectively. Alternatively, 2 was also obtained by the reaction of HL with [VO(acac) 2 ] in the presence of hydroxylamine, and by the reaction of 1 with hydroxylamine. Crystallographic data show that complexes 1 and 2 have similar molecular structures, in which the cis-dioxovanadium(V) center is coordinated to L -or HLox -, respectively, in a distorted octahedral environment. The catalytic activity of these compounds towards cyclohexane oxidation was evaluated using H 2 O 2 and t-BuOOH as oxidants. Both complexes presented > 70% selectivity for cyclohexylhydroperoxide formation. B3LYP/6-31G(d) calculations were used to confirm the geometry and to help assign the electronic spectra. Keywords: oxovanadium(V), bioinspired catalysts, peroxide activation IntroductionVanadium coordination chemistry has received attention in recent years due to its presence in several biological systems and its applications in catalysis. The first example of vanadium-dependent enzyme are the vanadium haloperoxidases (VHPOs), isolated from the marine algae Ascophyllum nodosum.1,2 Later, these enzymes were isolated from different sources such as seaweed, lichens and other algae and characterized as iodoperoxidases, bromoperoxidases and chloroperoxidases, depending on the most electronegative halogen the enzyme is capable of oxidizing.3 These enzymes are responsible for the two-electron oxidation catalyses of chloride, bromide Silva et al. 661 Vol. 22, No. 4, 2011 and iodide by hydrogen peroxide and are involved in the halogenation of a large variety of organic substrates in vivo. 4 The discovery of its structure initiated the investigation of vanadium...

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Section: Catalytic Oxidation Of Cyclohexanementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Synthesis, characterization and catalytic activity of two novel cis-dioxovanadium(v) complexes: [VO2(L)] and [VO2(Hlox)]

Silva¹,

Pinheiro²,

Chacon³

et al. 2011

J. Braz. Chem. Soc.

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“…We proposed the mechanism of binuclear Cu(II) complex catalyzed oxidation of primary alcohol to aldehyde. Cu(II)Cu(II) binuclear complex undergoes reduction to intermediate Cu(I)Cu(I) form without breaking the oxobridge[58] in CH 3 CN and oxidizes alcohol to aldehyde. Here, (NH 4 ) 2 S 2 O 8 enhances the formation of molecular oxygen in the system and helps the conversion of Cu(I)Cu(I) to Cu(II)Cu(II) by releasing water as byproduct to complete the catalytic cycle[59][60][61][62][63].…”

mentioning

confidence: 99%

Nickel(II), copper(II), cobalt(II), and palladium(II) complexes with a Schiff base: crystal structure, DFT study and copper complex catalyzed aerobic oxidation of alcohol to aldehyde

Sarma

Devi

Kalita

et al. 2015

Journal of Coordination Chemistry

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Ni(II), Cu(II), Co(II) and Pd(II) complexes were synthesized with a Schiff base containing thioether with ONS-donors chelating to the metal center. The ligand and complexes were characterized by elemental analysis, FT-IR, 1 H-NMR, UV-visible spectroscopy and magnetic studies. The crystal structures of the ligand and its Ni(II) and Pd(II) complexes were determined by single-crystal X-ray diffraction analysis. The structure reveals that ligand-chelated Ni(II) andPd(II) in slightly distorted octahedral and slightly distorted square planar environment, respectively. DFT studies of the Pd(II) complex reveal that the calculated structural parameters are very close with the experimentally observed data. The Cu(II) complex shows very good catalytic activity towards conversion of alcohol to aldehyde under aerobic oxidation with ammonium persulfate.

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“…24,25 Além disso, complexos de Cu 2+ com ligante semelhante já demonstraram boa atividade catalítica. 17 A inserção de substituintes com diferentes caráteres doador e aceptor de densidade eletrônica, como -OCH 3 e -NO 2 , respectivamente, visa entender a influencia destes na atividade catalítica destes complexos.…”

Section: -22unclassified

Theoretical Study of the Binuclear Complexes of Manganese (Ii) With Ligand 2-Hydroxybenzylglycine, Possibles Mimics for Catechol Oxidase

Silva¹,

Casellato²,

Machado³

2016

Química Nova

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. This work applies the Density Functional Theory (DFT) to study binuclear complexes of Mn 2+ with the ligand 2-hydroxibenzilglycine and its substituted derivatives. The results showed the isomer 2 with multiplicity 11-ete as the most stable between all the structures and multiplicities obtained. Then, the most stable complex with the -OCH 3 , -Br, -Cl and -NO 2 substituents were analyzed. Finally, the absolute hardness and the percentage of LUMO orbital participation for the substituted complexes were evaluated. Among them, the complexes with -NO 2 , -H, -Br groups were more likely to play the catalytic activity, respectively. Keywords: catechol oxidase; complexes of manganese; DFT. INTRODUÇÃOA catecol oxidase é uma metaloenzima binuclear de cobre da classe das oxido-redutases. Ela catalisa, especificamente, a oxidação do substrato catecol à correspondente orto-quinona com a redução do oxigênio à água (Figura 1). 1A catecol oxidase é encontrada em diversos frutos e vegetais, tendo como função a proteção destes contra patógenos e insetos. No ataque por agentes externos, a catecol oxidase atua na oxidação dos catecóis contidos na planta gerando as quinonas. A polimerização destas quinonas forma o pigmento escuro chamado melanina.2 Eicken e colaboradores propuseram um mecanismo para a ação catalítica da catecol oxidase. A estrutura do sítio ativo desta metaloenzima é composta por um centro binuclear de íons Cu 2+ com três resíduos de histidinas coordenadas a cada um destes centros bimetálicos. O ciclo inicia-se com a forma met da enzima, uma vez que essa é a forma nativa. Através do estudo de inibição com a feniltiouréia foi proposta uma ligação monodentada do substrato ao centro de CuB. A forma met reage com um mol de catecol e gera um mol da quinona correspondente. O centro de Cu 2+ -Cu 2+ sofre redução para a forma desoxi Cu + -Cu + possuindo uma molécula de solvente no CuA. Esta etapa é justificada pela formação de quantidades estequiométricas de quinona formadas na ausência de O 2 . Em seguida a forma desoxi se liga simultaneamente ao oxigênio e a uma molécula de catecol. Quando o oxigênio se liga aos íons Cu + , é formada a ponte do tipo m-h 2 :h 2 e ocorre a oxidação dos íons cuprosos a cúpricos (forma oxi). No complexo CO-O 2 2--catecol, dois elétrons são transferidos do substrato para o peróxido, seguido da quebra da ligação O-O, com a perda de água e a geração da quinona. Com isso, a forma met é restabelecida e o ciclo pode ser reiniciado (Figura 2). 3A catecol oxidase pode apresentar potencial tecnológico através do seu uso como biosensor no diagnóstico médico. Isso porque catecolaminas hormonais como a dopamina, adrenalina e noradrenalina podem ser quantificadas com a reação de produção de quinonas por ela promovida. 4 No trabalho de Lupetti e colaboradores a enzima foi usada para determinação de dopamina em formulações farmacêuti-cas.5 Outra possível aplicação é como agente oxidante de compostos poluentes em efluentes de despolpa do café, no caso, catecóis. 6Muitas vezes é praticamente impossível estu...

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Binuclear CuII complexes as catalysts for hydrocarbon and catechol oxidation reactions with hydrogen peroxide and molecular oxygen

Cited by 22 publications

References 51 publications

Synthesis, characterization and catalytic activity of two novel cis-dioxovanadium(v) complexes: [VO2(L)] and [VO2(Hlox)]

Synthesis, characterization and catalytic activity of two novel cis-dioxovanadium(v) complexes: [VO2(L)] and [VO2(Hlox)]

Nickel(II), copper(II), cobalt(II), and palladium(II) complexes with a Schiff base: crystal structure, DFT study and copper complex catalyzed aerobic oxidation of alcohol to aldehyde

Theoretical Study of the Binuclear Complexes of Manganese (Ii) With Ligand 2-Hydroxybenzylglycine, Possibles Mimics for Catechol Oxidase

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