A new oxo-vanadium complex employing an imidazole-rich tripodal ligand: A bioinspired bromide and hydrocarbon oxidation catalyst

Fernandez, Tatiana L.; Souza, Elizabeth T.; Visentin, Lorenzo C.; Santos, J. V. dos; Mangrich, Antônio S.; Faria, Roberto B.; Antunes, Octávio Augusto Ceva; Scarpellini, Marciela

doi:10.1016/j.jinorgbio.2009.02.001

Cited by 26 publications

(13 citation statements)

References 55 publications

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“…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: -13mentioning

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.…”

Section: Catalytic Oxidation Of Cyclohexanementioning

confidence: 99%

“…14,15 To obtain these oxidized products, the actual industrial process requires temperature and pressure over 150 °C and 115 psi, respectively; and only about 3-8% of overall conversion is attained. 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.…”

Section: Introductionmentioning

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: -13mentioning

confidence: 99%

Section: Catalytic Oxidation Of Cyclohexanementioning

confidence: 99%

Section: Introductionmentioning

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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“…33 The reaction was performed in acetonitrile at room temperature and inert atmosphere, using H 2 O 2 as oxidant. The catalyst:substrate:oxidant reaction ratio was 1:1000:1000, with a catalyst concentration of 7×10 -4 mol L -1…”

Section: Reactivity Cyclohexane Oxidationmentioning

confidence: 99%

“…The results are expressed as relative yields. 33 Oxidation of 3,5-di-tert-butyl-catechol The cathecolase activities of complexes 1 and 2 were measured by the oxidation of 3,5-di-tert-butylcatechol (3,5-dtbc) to the respective quinone at 25 °C. The experiments were performed with an Agilent 8453 spectrophotometer, and the reactions were followed at 400 nm, which is the characteristic absorption band of the oxidation product (3,5-di-tert-butylquinone, 3,5-dtbq).…”

Section: Reactivity Cyclohexane Oxidationmentioning

confidence: 99%

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

Martins¹,

Souza²,

Fernandez³

et al. 2010

J. Braz. Chem. Soc.

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Dois ligantes tridentados, HL1, [(2-hidroxibenzil)(2-(imidazol-2-il)etil)]amina, e HL2, [(2-hidroxibenzil)(2-(piridil-2-il)etil]amina, foram usados na síntese dos complexos binucleares [Cu 2 (L1) 2 ]Cl 2• 2H 2 O, complexo 1, e [Cu 2 (L2) 2 ] (ClO 4 ) 2• 1.5H 2 O, complexo 2, para serem empregados como catalisadores em processos de oxidação. Os complexos foram caracterizados por análise elementar e espectroscopias na região do infravermelho, ultravioleta-visível e ressonância paramagnética eletrônica. Foram também estudados por voltametria cíclica e titulação potenciométrica, a fim de caracterizar seus comportamentos em solução. A resolução da estrutura cristalina do complexo 1 mostrou um cátion binuclear contendo dois grupos fenóxido em ponte. Este arranjo possui uma distância Cu … Cu de 3.043(10) Å, similar à observada na catecol oxidase (2.90 Å). Os comportamentos catalíticos destes complexos foram investigados nas oxidações de cicloexano e de catecol. Na oxidação de cicloexano observou-se baixa atividade para ambos os complexos, que pode ser atribuída ao estereoimpedimento produzido pela falta de coplanaridade entre os anéis aromáticos do arcabouço dos ligantes, sugerindo que a aproximação entre o substrato e o centro ativo binuclear é uma etapa determinante no mecanismo da reação. Com relação à atividade de catecolase, foram observadas altas eficiências, com o complexo 2 sendo mais ativo que o complexo 1. Isto indica que o ligante piridina é capaz de estabilizar melhor o intermediário proposto para esse processo, que contém o centro Cu • 1.5H 2 O, complex 2, in order to obtain catalysts for oxidative processes. Both complexes were characterized by elemental analysis, IR, UV-Vis and EPR spectroscopies. In addition, they were studied by cyclic voltammetry and potentiometric titration in order to investigate their behavior in solution. The crystal structure of complex 1 revealed a binuclear cation where the metal centers are bridged by two phenoxo groups. This arrangement provides a Cu … Cu distance of 3.043(10) Å, which is similar to the observed for catechol oxidase (2.90 Å). The catalytic reactivities of both complexes were investigated for hydrocarbon and catechol oxidations. Complexes 1 and 2 led to low overall hydrocarbon oxidation conversion values of 6.34 % and 7.15 %, respectively. However, for complex 1, only cyclohexanol (Cy-OH) and cyclohexanone (Cy=O) were isolated as reaction products, with selectivities of 68.1% for Cy-OH. This low overall conversion is tentatively attributed to steric hindrance effects produced by the non-coplanar aromatic rings of the ligand scaffolds, which suggest that the access of the hydrocarbon molecule to the binuclear active center is a determinant step in the reaction mechanism. Investigation of catecholase activities has shown high efficiencies, with complex 2 being more active than complex 1. It indicates that the pyridine-containing ligand is able to stabilize the intermediate Cu I Cu I center which is proposed to be formed in this process. This is corroborated by t...

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Cerium‐Based Metal–Organic Framework with Intrinsic Haloperoxidase‐Like Activity for Antibiofilm Formation

Zhou

Wei

et al. 2022

Adv Funct Materials

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Biofilms adhering to surfaces have severe impacts on both public health and industry. Environmentally friendly strategies for combating biofilms are needed due to the biosafety issues brought by traditional commercial anti-biofilm additives. Enzyme-based strategies for biofilm treatment have attracted great research interest, but there is still a major challenge ahead due to the high economic cost and limited stability of natural enzymes. Inspired by the antifouling mechanism of natural haloperoxidase (HPO) secreted by marine algae, which catalyzes the oxidative bromination of bacterial quorum sensing signaling molecules, its artificial enzyme is proposed here in response to the situation mentioned above. A cerium-based metal-organic framework (Ce-MOF) is verified to possess HPO-like activity. Based on its favorable enzyme-like activity, the Ce-MOF exhibits remarkable antibacterial and biofilm formation suppression abilities. This study not only expands the variety of HPO-like artificial enzymes but also paves the way for the application prospect of Ce-MOFs in water pipe cleaning and biofouling treatment.

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A new oxo-vanadium complex employing an imidazole-rich tripodal ligand: A bioinspired bromide and hydrocarbon oxidation catalyst

Cited by 26 publications

References 55 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)]

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

Cerium‐Based Metal–Organic Framework with Intrinsic Haloperoxidase‐Like Activity for Antibiofilm Formation

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