Oxygen activation by copper camphor complexes

Roseiro, Alexandra P. S.; Adão, Pedro; Galvão, Adelino M.; Pessoa, João Costa; Rego, A.M. Botelho do; Carvalho, M. Fernanda N. N.

doi:10.1039/c5qi00064e

Cited by 5 publications

(3 citation statements)

References 51 publications

(87 reference statements)

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“…The mechanism of O 2 activation by Cu(II) could involve Cu(I), as reported elsewhere. 46 Regarding Co-catalysts, upon O 2 addition most Co(II) complexes form kinetically inert lowspin Co(III) terminal superoxide or μ-peroxide compounds that are active only in catalysis by addition of a coreductant (often, an organic ligand with redox properties). 47 Hanna et al reported the oxidation of DMPO to the DMPO/ • OH adduct by Co(II) and ethylenediamine when O 2 was present.…”

Section: Discussionmentioning

confidence: 99%

New Insights about the Selectivity in the Activation of Hydrogen Peroxide by Cobalt or Copper Hydrogel Heterogeneous Catalysts in the Generation of Reactive Oxygen Species

et al. 2016

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We report the performance of Co(II) and Cu(II) coordination complexes on H2O2 activation. The heterogeneous catalysts containing aliphatic amine, N-heterocycle, and/or carboxylic acid ligands in hydrogel materials coordinated with Co(II) or Cu(II) were used in this study. These complexes were characterized by solid-state NMR, X-ray photoelectron spectroscopy (XPS), and X-ray fluorescence techniques in order to quantify the superficial and bulk metal ion centers together with the aim of elucidating the ligands involved in the uptake of Co and Cu ions. The release of free radicals on H2O2 activation and the identity of reactive oxygen species were studied by spin trapping using DMPO in electron spin resonance (ESR) experiments. The Co(II) complex/H2O2 systems produced O2, anion superoxide (O2 •–), and hydroxyl radical (OH•), which diffused into the solution at the time that a decrease in pH was detected. A possible catalytic mechanism would involve the Co(II)/Co(III) redox couple, according to XPS results. In the same way, the Cu(II) complex/H2O2 systems produced O2 and OH•, with evidence of Cu(II)/Cu(I) redox cycle. For these catalytic systems, there was no direct evidence of intermediary reactive species. The identity of the ligands played a crucial role in the efficiency of catalytic activation. In addition, in the absence of H2O2, the dissolved O2 was activated by most of the complexes tested, releasing only OH•.

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Section: Discussionmentioning

confidence: 99%

New Insights about the Selectivity in the Activation of Hydrogen Peroxide by Cobalt or Copper Hydrogel Heterogeneous Catalysts in the Generation of Reactive Oxygen Species

et al. 2016

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“…The hydrogen on the hydroxyl group is detached and complexed with anions, and phenol is converted into a phenoxyl radical . Due to the instability of Cu(I), it undergoes electron transfer with oxygen, activating molecular oxygen to generate the [O–O–Cu(II)HCl 4 ] 2– complex. , Because of the strong electronegativity of [O–O–Cu(II)HCl 4 ] 2– and the strong electron-withdrawing ability of the carbonyl group, the para position of the phenoxy radical shows strong electronegativity. Therefore, [O–O–Cu(II)HCl 4 ] 2– preferentially attacks the para position of the phenoxy group, generating p -benzoquinone and water.…”

Section: Resultsmentioning

confidence: 99%

Separation of Phenol from Oil and In Situ Oxidation of Phenol to p-Benzoquinone by Metal Complex Ionic Liquids

Li,

Feng,

Hou

et al. 2024

Ind. Eng. Chem. Res.

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Phenol mainly separated from coal tar is a valuable raw material in industry. Ionic liquids and deep eutectic solvents are environmentally friendly extractants for phenol separation through hydrogen bond interaction. However, the strong interaction makes extractants difficult to regenerate. p-Benzoquinone is a high-value-added product, which can be produced by the selective oxidation of phenol, but the conversion and selectivity are not high. Herein, metal complex ionic liquids were synthesized and used for separation of phenol from oil and conversion of phenol to p-benzoquinone without the addition of catalysts. The ionic liquids can separate phenol efficiently with an extract rate of more than 99%, and the phenol in ionic liquids can be totally oxidized under mild conditions. This work reached a phenol conversion rate of 100% and a selectivity of up to 96.4% for p-benzoquinone under the conditions of methanol as a solvent, oxygen as an oxidant, an oxygen pressure of 3.30 MPa, a temperature of 70 °C, a reaction time of 60 min, and n phenol/n [Emim]2[CuCl4] = 2:1. The regenerated ionic liquid can be reused for both the separation and conversion of phenol with no obvious change. The reaction path and mechanism are speculated and verified. The results show that [CuCl4]2– plays the key role in both the separation and oxidization of phenol. This work opens up a promising direction for phenolic compound separation coupled with efficient conversion to high-value-added products.

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“…48 The reactions were made in water and ethanol, respectively, with CCA-H and CCA-Li, although CCA-Li performs well in water. The choice aims at inhibit Li + /H + exchange that would be enhanced in H 2 O.…”

Section: Synthetic Approachmentioning

confidence: 99%

Camphor-based CCR5 blocker lead compounds – a computational and experimental approach

et al. 2016

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The C-C chemokine receptor type 5 (CCR5) is a transmembrane receptor that plays a pivotal role as a HIV anchor to human cell membranes, mediating viral entry. CCR5 antagonists, acting by blocking the receptor and preventing its interaction with the HIV proteins, are key agents towards effective anti-viral therapy. This work describes the computational study, synthesis and viral inhibition assay of a number of camphor derivatives as a first step towards new drug leads to block this specific entry pathway. Viral inhibition assays have identified three molecules, camphor carboxylic acid, its tri(hydroxymethyl)aminomethane amide derivative, and an hydroxyl-imide camphor derivative as promising agents to develop new drugs, with IC 50 values (0.16, 0.22 and 1.02 mM, respectively) one order below that of maraviroc (0.02 mM), a clinically used CCR5 antagonist.

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Oxygen activation by copper camphor complexes

Abstract: In situreduction of CuCl2enables formation of Cu(i) complexes prone to activate molecular oxygen from air towards catalytic oxidation of 1,3-dicarbonyls.

Cited by 5 publications

References 51 publications

New Insights about the Selectivity in the Activation of Hydrogen Peroxide by Cobalt or Copper Hydrogel Heterogeneous Catalysts in the Generation of Reactive Oxygen Species

New Insights about the Selectivity in the Activation of Hydrogen Peroxide by Cobalt or Copper Hydrogel Heterogeneous Catalysts in the Generation of Reactive Oxygen Species

Separation of Phenol from Oil and In Situ Oxidation of Phenol to p-Benzoquinone by Metal Complex Ionic Liquids

Camphor-based CCR5 blocker lead compounds – a computational and experimental approach

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