A Unique Fe–N₄ Coordination System Enabling Transformation of Oxygen into Superoxide for Photocatalytic CH Activation with High Efficiency and Selectivity

Advanced Materials, Journal Year: 2022, Volume and Issue: 34(27)

Published: May 11, 2022

Selective oxidation of CH bonds is one the most important reactions in organic synthesis. However, activation α-CH bond ethylbenzene by use photocatalysis-generated superoxide anions (O2•- ) remains a challenge. Herein, formation individual Fe atoms on polymeric carbon nitride (CN), that activates O2 to create O2•- for facilitating reaction form acetophenone, demonstrated. By utilizing density functional theory and materials characterization techniques, it shown are coordinated four N CN resultant low-spin Fe-N4 system (t2g6 eg0 not only great adsorption site oxygen molecules, but also allows fast transfer electrons generated framework adsorbed , producing . The triggered ions turns out have high conversion rate 99% as well an acetophenone selectivity 99%, which can be ascribed novel pathway different from conventional route involving hydroxyl radicals production phenethyl alcohol. Furthermore, possesses potential other besides oxidation.

Language: Английский

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Photocatalytic C(sp³) radical generationviaC–H, C–C, and C–X bond cleavage

Chemical Science, Journal Year: 2022, Volume and Issue: 13(19), P. 5465 - 5504

Published: Jan. 1, 2022

C(sp 3 ) radicals (R˙) are of broad research interest and synthetic utility.

Language: Английский

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CdS Quantum Dots as Potent Photoreductants for Organic Chemistry Enabled by Auger Processes

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(27), P. 12229 - 12246

Published: June 30, 2022

Strong reducing agents (<−2.0 V vs saturated calomel electrode (SCE)) enable a wide array of useful organic chemistry, but suffer from variety limitations. Stoichiometric metallic reductants such as alkali metals and SmI2 are commonly employed for these reactions; however, considerations including expense, ease use, safety, waste generation limit the practicality methods. Recent approaches utilizing energy multiple photons or electron-primed photoredox catalysis have accessed reduction potentials equivalent to Li0 shown how this enables selective transformations aryl chlorides via radicals. However, in some cases, low stability catalytic intermediates can turnover numbers. Herein, we report ability CdS nanocrystal quantum dots (QDs) function strong photoreductants present evidence that highly electron is generated two consecutive photoexcitations QDs with intermediate reductive quenching. Mechanistic experiments suggest Auger recombination, photophysical phenomenon known occur photoexcited anionic QDs, generates transient thermally excited electrons observed reductions. Using blue light-emitting diodes (LEDs) sacrificial amine reductants, phosphate esters up −3.4 SCE photoreductively cleaved afford hydrodefunctionalized functionalized products. In contrast small-molecule catalysts, stable under conditions numbers 47 500 been achieved. These also effect other challenging reductions, tosylate protecting group removal amines, debenzylation benzyl-protected alcohols, ring opening cyclopropane carboxylic acid derivatives.

Language: Английский

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Solvent‐in‐Gas System for Promoted Photocatalytic Ammonia Synthesis on Porous Framework Materials

Advanced Materials, Journal Year: 2023, Volume and Issue: 35(14)

Published: Jan. 17, 2023

Photocatalytic nitrogen reduction reaction (PNRR) is emerging as a sustainable ammonia synthesis approach to meet global carbon neutrality. Porous framework materials with well-designed structures have great opportunities in PNRR; however, they suffer from unsatisfactory activity the conventional gas-in-solvent system (GIS), owing hindrance of utilization and strong competing hydrogen evolution caused by overwhelming solvent. In this study, porous are combined novel "solvent-in-gas" system, which can bring their superiority into full play. This enables photocatalysts directly operate gas-dominated environment limited proton source uniformly suspended it, achieving accumulation high-concentrated within while efficiently restricting solvent-photocatalyst contact. An over eightfold increase production rate (1820.7 µmol g-1 h-1 ) compared GIS an apparent quantum efficiency high ≈0.5% at 400 nm achieved. system-level strategy further finds applicability photocatalytic CO2 reduction, featuring it staple for photosynthetic methodology.

Language: Английский

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Semiconductor quantum dots: a versatile platform for photoredox organic transformation

Journal of Materials Chemistry A, Journal Year: 2023, Volume and Issue: 11(7), P. 3262 - 3280

Published: Jan. 1, 2023

A summary of the research progress diverse organic transformations over semiconductor quantum dot based photofunctional catalysts is provided.

Language: Английский

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MoS2 decorated CdS composite catalyst for photoredox-mediated C–N coupling of amines to imines and hydrogen production

Molecular Catalysis, Journal Year: 2024, Volume and Issue: 557, P. 113991 - 113991

Published: Feb. 29, 2024

Language: Английский

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Guest‐Regulated Generation of Reactive Oxygen Species from Porphyrin‐Based Multicomponent Metallacages for Selective Photocatalysis

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(14)

Published: Feb. 2, 2024

Abstract The development of novel materials for highly efficient and selective photocatalysis is crucial their practical applications. Herein, we employ the host‐guest chemistry porphyrin‐based metallacages to regulate generation reactive oxygen species further use them photocatalytic oxidation benzyl alcohols. Upon irradiation, sole metallacage ( 6 ) can generate singlet 1 O 2 effectively via excited energy transfer, while its complex with C 70 ⊃C opens a pathway electron transfer promote formation superoxide anion (O ⋅ − ), producing both . addition 4,4′‐bipyridine (BPY) forms more stable ⊃BPY) coordination Zn‐porphyrin faces BPY, which drives fullerenes out cavities restores ability generation. Therefore, alcohols are oxidized into aldehydes upon irradiation in presence or ⊃BPY, they benzoic acids when employed as photosensitizing agent. This study demonstrates strategy that utilizes photooxidation reactions, could utilization related complexes

Language: Английский

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Heterogeneous Photocatalytic Strategies for C(sp³)−H Activation

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(13)

Published: Jan. 16, 2024

Abstract Activation of ubiquitous C(sp 3 )−H bonds is extremely attractive but remains a great challenge. Heterogeneous photocatalysis offers promising and sustainable approach for activation has been fast developing in the past decade. This Minireview focuses on mechanism strategies heterogeneous photocatalytic activation. After introducing mechanistic insights, including precise design active sites, regulation reactive radical species, improving charge separation reactor innovations are discussed. In addition, recent advances hydrocarbons, alcohols, ethers, amines amides by summarized. Lastly, challenges opportunities outlined to encourage more efforts development this exciting field.

Language: Английский

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Reductive Carbon–Carbon Coupling on Metal Sites Regulates Photocatalytic CO₂ Reduction in Water Using ZnSe Quantum Dots

Angewandte Chemie International Edition, Journal Year: 2022, Volume and Issue: 61(31)

Published: May 30, 2022

Colloidal quantum dots (QDs) consisting of precious-metal-free elements show attractive potentials towards solar-driven CO2 reduction. However, the inhibition hydrogen (H2 ) production in aqueous solution remains a challenge. Here, we describe first example carbon-carbon (C-C) coupling reaction to block competing H2 evolution photocatalytic reduction water. In specific system taking ZnSe QDs as photocatalysts, introduction furfural can significantly suppress leading CO with rate ≈5.3 mmol g-1 h-1 and turnover number (TON) >7500 under 24 h visible light. Meanwhile, is upgraded self-coupling product yield 99.8 % based on consumption furfural. Mechanistic insights that reductive occurs surface Zn-sites consume electrons protons originally used for production, while formation pathway at anion vacancies from remains.

Language: Английский

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Stop-Flow Microtubing Reactor-Assisted Visible Light-Induced Hydrogen-Evolution Cross Coupling of Heteroarenes with C(sp³)–H Bonds

ACS Catalysis, Journal Year: 2022, Volume and Issue: 12(8), P. 4473 - 4480

Published: March 31, 2022

The synthesis of valuable alkyl-substituted heteroarenes from abundant and inexpensive feedstocks under mild conditions is attractive highly desirable in pharmaceutical natural product synthesis. Minisci-type cross dehydrogenative coupling between C(sp3)–H bonds offers direct access to these important scaffolds a step-economic manner. Herein, assisted by stop-flow microtubing reactors, an operationally simple protocol for the visible light-induced hydrogen-evolution with unactivated was developed metal- external oxidant-free A wide range alkylated generated common feedstock chemicals, including ethane. Mechanistic studies indicated that photoredox-induced hydrogen atom transfer processes followed rearomatization delivered desired products. merits this strategy were further demonstrated late-stage functionalization various complex bioactive molecules.

Language: Английский

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