Oxygen-18 Labeling Defines a Ferric Peroxide (Compound 0) Mechanism in the Oxidative Deformylation of Aldehydes by Cytochrome P450 2B4

ACS catalysis

Published On 2024/1/31

Most cytochrome P450 (P450) oxidations are considered to occur with the active oxidant being a perferryl oxygen (FeO3+, Compound I). However, a ferric peroxide (FeO2̅, Compound 0) mechanism has been proposed, as well, particularly for aldehyde substrates. We investigated three of these systems, the oxidative deformylation of the model substrates citronellal, 2-phenylpropionaldehyde, and 2-methyl-2-phenylpropionaldehyde by rabbit P450 2B4, using 18O labeling. The formic acid product contained one 18O derived from 18O2, which is indicative of a dominant Compound 0 mechanism. The formic acid also contained only one 18O derived from H218O, which ruled out a Compound I mechanism. The possibility of a Baeyer–Villiger reaction was examined by using synthesized possible intermediates, but our data do not support its presence. Overall, these findings unambiguously demonstrate the role of the …

Journal

ACS catalysis

Published On

2024/1/31

Volume

14

Page

2388-2394

Authors

Fred Guengerich

Fred Guengerich

Vanderbilt University

Position

Professor of Biochemistry

H-Index(all)

175

H-Index(since 2020)

51

I-10 Index(all)

0

I-10 Index(since 2020)

0

Citation(all)

0

Citation(since 2020)

0

Cited By

0

Research Interests

Enzymology

drug metabolism

cytochrome P450

mutagenesis

University Profile Page

Kevin D. McCarty

Kevin D. McCarty

Vanderbilt University

Position

H-Index(all)

4

H-Index(since 2020)

4

I-10 Index(all)

0

I-10 Index(since 2020)

0

Citation(all)

0

Citation(since 2020)

0

Cited By

0

Research Interests

Biochemistry

University Profile Page

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Fred Guengerich

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Fred Guengerich

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Fred Guengerich

Fred Guengerich

Vanderbilt University

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Fred Guengerich

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2023/11/24

Article Details
Fred Guengerich

Fred Guengerich

Vanderbilt University

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ACS Catalysis

In Situ Dissociated Chalcogenide Anions Regulate the Bi-Catalyst/Electrolyte Interface with Accelerated Surface Reconstruction toward Efficient CO2 Reduction

Understanding the structure change of the electrocatalysts during the electrochemical CO2 reduction reaction (CO2RR) is of crucial importance to illustrate the structure–performance relationship. Here, the reconstruction of Bi–O–M (M = S, Se, or Cl) nanosheets induced by the in situ dissociated chalcogenide anions toward efficient CO2RR to formate is reported. The surface work function and potential of zero charge (PZC) of metallic Bi are reduced upon anions’ adsorption, facilitating the regeneration of active Bi–O structures during reduction. Moreover, a correlation between the pKb values of the anions and the local pH of the catalyst/electrolyte interface can be established. The anion with a smaller pKb (S2– < Se2– < Cl–) would induce a more alkaline environment and further promote the formation of Bi–O structures. Among them, Bi2O2S with in situ released S2– during reconstruction exhibits the best CO2RR-to …

2023/12/22

Article Details
Li Peng (彭丽)

Li Peng (彭丽)

Xiamen University

ACS Catalysis

Nitrogen, Sulfur Co-doped Hollow Carbon-Encapsulated Cu/Co2P for Selective Oxidation Esterification of Furfurals

With the remarkable capability of encapsulating multifunctional active sites inside, carbon-based materials play vital roles in multifarious chemical transformations such as hydrogenation reactions, oxidation reactions, esterification reactions, etc. Herein, we propose an efficient and facile approach to construct a Cu/Co2P@C-NS catalyst, which consists of nitrogen–sulfur co-doped carbon (C-NS) encapsulated cobalt phosphide (Co2P) and copper double active sites. This approach focuses on the design and preparation of core–shell materials, that is, the ZIF-67 core is coated with an adhesive poly(cyclotriphosphazene-co-4,4′-sulfonyldiphenol) (PZS) polymer shell. The ZIF-67 core possesses a highly porous structure, coexistence of carbon and nitrogen elements, and uniform dispersion of Co species, making it an ideal template. The heteroatomic PZS polymer with decent coating ability makes it a promising …

Wolfgang Kroutil

Wolfgang Kroutil

Karl-Franzens-Universität Graz

ACS catalysis

Deciphering the Unconventional Reduction of C═ N Bonds by Old Yellow Enzymes Using QM/MM

The reduction of C═X (X = N, O) bonds is a cornerstone in both synthetic organic chemistry and biocatalysis. Conventional reduction mechanisms usually involve a hydride ion targeting the less electronegative carbon atom. In a departure from this paradigm, our investigation into Old Yellow Enzymes (OYEs) reveals a mechanism involving transfer of hydride to the formally more electronegative nitrogen atom within a C═N bond. Beyond their known ability to reduce electronically activated C═C double bonds, e.g., in α, β-unsaturated ketones, these enzymes have recently been shown to reduce α-oximo-β-ketoesters to the corresponding amines. It has been proposed that this transformation involves two successive reduction steps and proceeds via imine intermediates formed by the reductive dehydration of the oxime moieties. We employ advanced quantum mechanics/molecular mechanics (QM/MM) simulations …

Francesc Illas

Francesc Illas

Universidad de Barcelona

ACS catalysis

Comprehensive Density Functional and Kinetic Monte Carlo Study of CO2 Hydrogenation on a Well-Defined Ni/CeO2 Model Catalyst: Role of Eley–Rideal Reactions

A detailed multiscale study of the mechanism of CO2 hydrogenation on a well-defined Ni/CeO2 model catalyst is reported that couples periodic density functional theory (DFT) calculations with kinetic Monte Carlo (kMC) simulations. The study includes an analysis of the role of Eley–Rideal elementary steps for the water formation step, which are usually neglected on the overall picture of the mechanism, catalytic activity, and selectivity. The DFT calculations for the chosen model consisting of a Ni4 cluster supported on CeO2 (111) show large enough adsorption energies along with low energy barriers that suggest this catalyst to be a good option for high selective CO2 methanation. The kMC simulations results show a synergic effect between the two 3-fold hollow sites of the supported Ni4 cluster with some elementary reactions dominant in one site, while other reactions prefer the another, nearly equivalent site. This …

Mark Muldoon

Mark Muldoon

Queen's University Belfast

ACS catalysis

Insights into the Palladium(II)-Catalyzed Wacker-Type Oxidation of Styrene with Hydrogen Peroxide and tert-Butyl Hydroperoxide

Wacker oxidations are ubiquitous in the direct synthesis of carbonyl compounds from alkenes. While the reaction mechanism has been widely studied under aerobic conditions, much less is known about such processes promoted with peroxides. Here, we report an exhaustive mechanistic investigation of the Wacker oxidation of styrene using hydrogen peroxide (H2O2) and tert-butyl hydroperoxide (TBHP) as oxidants by combining density functional theory and microkinetic modeling. Our results with H2O2 uncover a previously unreported reaction pathway that involves an intermolecular proton transfer assisted by the counterion [OTf]− present in the reaction media. Furthermore, we show that when TBHP is used as an oxidant instead of H2O2, the reaction mechanism switches to an intramolecular protonation sourced by the HOtBu moiety generated in situ. Importantly, these two mechanisms are predicted to …

Egon Campos dos Santos

Egon Campos dos Santos

Stockholms universitet

ACS Catalysis

A Water-Promoted Mars−van Krevelen Reaction Dominates Low-Temperature CO Oxidation over Au-Fe2O3 but Not over Au-TiO2

We provide experimental evidence that is inconsistent with often proposed Langmuir−Hinshelwood (LH) mechanistic hypotheses for water-promoted CO oxidation over Au–Fe2O3. Passing CO and H2O, but no O2, over Au-γ-Fe2O3 at 25 °C, we observe significant CO2 production, inconsistent with LH mechanistic hypotheses. Experiments with H218O further show that previous LH mechanistic proposals cannot account for water-promoted CO oxidation over Au-γ-Fe2O3. Guided by density functional theory, we instead postulate a water-promoted Mars–van Krevelen (w-MvK) reaction. Our proposed w-MvK mechanism is consistent both with observed CO2 production in the absence of O2 and with CO oxidation in the presence of H218O and 16O2. In contrast, for Au-TiO2, our data is consistent with previous LH mechanistic hypotheses.

Andrew Gewirth

Andrew Gewirth

University of Illinois at Urbana-Champaign

ACS Catalysis

Inducing Microstrain in Electrodeposited Pt through Polymer Addition for Highly Active Oxygen Reduction Catalysis

We investigate an approach to tune the d-band center and enhance the oxygen reduction reaction (ORR) activity of Pt material without relying on foreign metals or the process of alloying/dealloying. It is known that Pt exhibits suboptimal ORR catalytic activity due to its strong binding to oxygen, therefore requiring a downshift in the d-band center by approximately 0.2 eV to weaken the Pt-O binding energy and boost ORR kinetics. We found that the d-band center can be tuned by inducing microstrain in the Pt electrodeposit, simply achieved by introducing polymer into the electrodeposition bath. Pt electrodes (Pt-P1 and Pt-PLA) prepared with the addition of poly-N-(6-aminohexyl)acrylamide (P1) or poly-l-arginine (PLA) exhibit improved ORR activity compared to Pt electrodeposited without polymer addition (Pt-alone) in both acidic and basic environments, with the order of activity being Pt-P1 > Pt-PLA > Pt-alone. Pt-P1 …

Tyler Sours

Tyler Sours

University of California, Davis

ACS catalysis

Screening Cu-Zeolites for Methane Activation Using Curriculum-Based Training

Machine learning (ML), when used synergistically with atomistic simulations, has recently emerged as a powerful tool for accelerated catalyst discovery. However, the application of these techniques has been limited by the lack of interpretable and transferable ML models. In this work, we propose a curriculum-based training (CBT) philosophy to systematically develop reactive machine learning potentials (rMLPs) for high-throughput screening of zeolite catalysts. Our CBT approach combines several different types of calculations to gradually teach the ML model about the relevant regions of the reactive potential energy surface. The resulting rMLPs are accurate, transferable, and interpretable. We further demonstrate the effectiveness of this approach by exhaustively screening thousands of [CuOCu]2+ sites across hundreds of Cu-zeolites for the industrially relevant methane activation reaction. Specifically, this large …

Cathleen M Crudden

Cathleen M Crudden

Queens University

ACS Catalysis

Electrocatalytic CO2 Reduction with Atomically Precise Au13 Nanoclusters: Effect of Ligand Shell on Catalytic Performance

Supported gold nanoclusters of the formula [Au13(L)5Cl2]3+ where L = N-heterocyclic carbene (NHC) or phosphine ligands are examined in the electrocatalytic CO2 reduction reaction (eCO2RR) in a membrane electrode assembly cell configuration. Gold nanoclusters bearing bisNHC ligands are shown to exhibit improved catalytic performance compared with diphosphine-stabilized nanoclusters after activation at the optimum treatment temperatures. The thermal properties of the nanoclusters are shown to have a significant impact on their catalytic activity. Thermogravimetric analysis, UV–vis absorption spectroscopy, and X-ray photoelectron spectroscopy revealed that thermal treatment of [Au13(diphosphine)5Cl2]3+ nanoclusters results in complete loss of diphosphine ligands while [Au13(bisNHC)5Cl2]3+ nanoclusters show stepwise and partial removal of bisNHC ligands. We propose that the partial removal of …