Covalent organic frameworks for direct photosynthesis of hydrogen peroxide from water, air and sunlight

Nature Communications, Journal Year: 2023, Volume and Issue: 14(1)

Published: July 19, 2023

Solar-driven photosynthesis is a sustainable process for the production of hydrogen peroxide, efficiency which plagued by side reactions. Metal-free covalent organic frameworks (COFs) that can form suitable intermediates and inhibit reactions show great promise to photo-synthesize H2O2. However, insufficient formation separation/transfer photogenerated charges in such materials restricts H2O2 production. Herein, we provide strategy design donor-acceptor COFs greatly boost photosynthesis. We demonstrate optimal intramolecular polarity COFs, achieved using amounts phenyl groups as electron donors, maximize free charge generation, leads high yield rates (605 μmol g-1 h-1) from water, oxygen visible light without sacrificial agents. Combining in-situ characterization with computational calculations, describe how triazine N-sites N 2p states play crucial role H2O activation selective oxidation into further experimentally be efficiently produced tap, river or sea water natural sunlight air decontamination.

Language: Английский

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Catalysis by Bidentate Iodine(III)-Based Halogen Donors: Surpassing the Activity of Strong Lewis Acids

The Journal of Organic Chemistry, Journal Year: 2021, Volume and Issue: 86(7), P. 5317 - 5326

Published: March 25, 2021

The poorly understood mode of activation and catalysis bidentate iodine(III)-based halogen donors have been quantitatively explored in detail by means state-of-the-art computational methods. To this end, the uncatalyzed Diels-Alder cycloaddition reaction between cyclohexadiene methyl vinyl ketone is compared to analogous process mediated a iodine(III)-organocatalyst related, highly active iodine(I) species. It found that iodine(III)-catalyst accelerates lowering barrier up 10 kcal mol-1 parent reaction. Our quantitative analyses reveal origin significant reduction steric (Pauli) repulsion diene dienophile, which originates from both more asynchronous polarization π-system dienophile away incoming diene. Notably, activity can be further enhanced increasing electrophilic nature system. Thus, novel systems are designed whose actually surpasses strong Lewis acids such as BF3.

Language: Английский

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Cycloaddition Reactivities Analyzed by Energy Decomposition Analyses and the Frontier Molecular Orbital Model

Accounts of Chemical Research, Journal Year: 2022, Volume and Issue: 55(17), P. 2467 - 2479

Published: Aug. 25, 2022

ConspectusThis Account describes our quest to understand and predict organic reactivity, a principal goal of physical theoretical chemistry. The focus is on the development testing models for prediction cycloaddition reactivities selectivities. We describe involvement Houk group, other groups, in evolution that can achieve ever greater accuracy as well provide practical heuristic understanding prediction.Is venerable frontier molecular orbital (FMO) model, basis Kenichi Fukui's 1981 Nobel Prize, still useful, or must it be replaced with more advanced models? In particular, such Conceptual Density Functional, Pauli Exclusion Model, recent popularity Electrostatic Potential Plots Dispersion Energies have not only added understanding, but they also created uncertainty about whether simple FMO model has place 21st century discussions. This addresses this issue asserts value model.Beginning brief descriptions selected reactivity starting early donor–acceptor (nucleophile–electrophile) charge-transfer concepts, reviews Salem Klopman's orbital, electrostatic repulsion conceptual DFT by Parr later Domingo others, Bickelhaupt Distortion/Interaction Activation Strain Bickelhaupt-Hamlin's Pauli-repulsion lowering model.Computations analyses four well-studied Diels–Alder cycloadditions, both normal inverse electron-demand types, are presented. Most were studied earlier published work presented here new insights from calculations modern methods. Depending types substrates (cycloaddends), dominant factors controlling interactions, electrostatics polarization, dispersion effects, combination all these.By comparing especially influence we show why powerful─and theoretically meaningful─heuristic predicting reactivity. present method effects activation barriers, ρ(1.1). use reaction coordinate, extent along path, advocated emphasize role repulsive occupied interactions reactivity.Fukui's effective because parallel quantities continues guide experiments.

Language: Английский

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An easy-to-perform evaluation of steric properties of Lewis acids

Chemical Science, Journal Year: 2023, Volume and Issue: 14(9), P. 2275 - 2288

Published: Jan. 1, 2023

An easy-to-perform approach to assess and quantify steric properties of Lewis acids is reported. The novel LAB-Rep model (Lewis acid/base repulsion model) introduced, which judges in pairs.

Language: Английский

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Inverted Region in Electrochemical Reduction of CO₂Induced by Potential-Dependent Pauli Repulsion

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(26), P. 14267 - 14275

Published: June 9, 2023

Electrochemical CO2 reduction reaction (eCO2RR) is of great significance to energy and environmental engineering, while fundamental questions remain regarding its mechanisms. Herein, we formulate a understanding the interplay between applied potential (U) kinetics activation in eCO2RR on Cu surfaces. We find that nature mechanism varies with U, it sequential electron-proton transfer (SEPT) dominant at working U but switched concerted proton-electron (CPET) highly negative U. then identify barrier electron-transfer step SEPT exhibits an inverted region as decreases, which originates from rapidly rising Pauli repulsion physisorption decreasing further demonstrate catalyst designs effectively suppress adverse effect repulsion. This may be general for electrochemical reactions closed-shell molecules.

Language: Английский

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Understanding the reactivity of frustrated Lewis pairs with the help of the activation strain model–energy decomposition analysis method

Chemical Communications, Journal Year: 2022, Volume and Issue: 58(32), P. 4931 - 4940

Published: Jan. 1, 2022

This Feature article presents recent representative applications of the combination Activation Strain Model reactivity and Energy Decomposition Analysis methods to understand Frustrated Lewis Pairs (FLPs).

Language: Английский

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Catalytic Asymmetric Conjugate Reduction

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(20)

Published: Feb. 9, 2023

Enantioselective reduction reactions are privileged transformations for the construction of trisubstituted stereogenic centers. While these include established synthetic strategies, such as asymmetric hydrogenation, methods based on enantioselective addition hydridic reagents to electrophilic prochiral substrates have also gained importance. In this context, conjugate (ACR) α,β-unsaturated compounds has become a convenient approach synthesis chiral with stereocenters in α-, β-, or γ-position electron-withdrawing functional groups. Because activating groups diverse and amenable further derivatizations, ACRs provide general powerful entry towards variety valuable building blocks. This Review provides comprehensive collection catalytic ACR involving transition-metal, organic, enzymatic catalysis since its first versions dating back late 1970s.

Language: Английский

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Substituent Effects in Bioorthogonal Diels–Alder Reactions of 1,2,4,5‐Tetrazines

Chemistry - A European Journal, Journal Year: 2023, Volume and Issue: 29(29)

Published: Feb. 28, 2023

1,2,4,5-Tetrazines are increasingly used as reactants in bioorthogonal chemistry due to their high reactivity Diels-Alder reactions with various dienophiles. Substituents the 3- and 6-positions of tetrazine scaffold known have a significant impact on rate cycloadditions; this is commonly explained basis frontier molecular orbital theory. In contrast, we show that differences between classes tetrazines not controlled by interactions. particular, demonstrate mono-substituted decreased Pauli repulsion, which leads more asynchronous approach associated reduced distortion energy. This follows recent Vermeeren-Hamlin-Bickelhaupt model increase asymmetric reactions. addition, reveal ethylene good compound for other alkenes

Language: Английский

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Mechanistic Insight into Lewis Acid-Catalyzed Cycloaddition of Bicyclo[1.1.0]butanes with Ketene: Bicyclo[1.1.0]butanes Serving as an Electrophile

The Journal of Organic Chemistry, Journal Year: 2024, Volume and Issue: 89(2), P. 1241 - 1248

Published: Jan. 1, 2024

Lewis acid-catalyzed cycloaddition between bicyclo[1.1.0]butanes (BCBs) and unsaturated substrates has recently been demonstrated to be a powerful strategy for synthesizing bicyclo[2.1.1]hexanes. However, their reaction mechanisms remain elusive. This computational work explored the developed TMSOTf-catalyzed of BCB ketone ketene determined rate-determining step as activation ketone. Contrary previous proposal enolate active species, this instead identified catalytically species partially acid-activated cation, which shows greater electrophilicity larger orbital interactions with compared those pristine BCB. The most favorable pathway uniquely utilizes activated an electrophile react nucleophile, while previously proposed is relatively inactive. Moreover, in situ-generated TfO anion revealed non-innocent, its coordination mode orientation could affect kinetics.

Language: Английский

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What defines electrophilicity in carbonyl compounds

Chemical Science, Journal Year: 2024, Volume and Issue: 15(11), P. 3980 - 3987

Published: Jan. 1, 2024

The origin of the electrophilicity a series cyclohexanones and benzaldehydes is investigated using activation strain model quantitative Kohn–Sham molecular orbital (MO) theory.

Language: Английский

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