Radical Hydrocarboxylation of Unactivated Alkenes via Photocatalytic Formate Activation

Journal of the American Chemical Society, Год журнала: 2023, Номер 145(20), С. 10991 - 10997

Опубликована: Май 15, 2023

Herein we disclose a strategy to promote the hydrocarboxylation of unactivated alkenes using photochemical activation formate salts. We illustrate that an alternative initiation mechanism circumvents limitations prior approaches and enables this challenging substrate class. Specifically, found accessing requisite thiyl radical initiator without exogenous chromophore eliminates major byproducts have plagued attempts exploit similar reactivity for alkene substrates. This redox-neutral method is technically simple execute effective across broad range Feedstock alkenes, such as ethylene, are hydrocarboxylated at ambient temperature pressure. A series cyclization experiments indicate how described in report can be diverted by more complex processes.

Язык: Английский

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Redox Molecular Junction Metal‐Covalent Organic Frameworks for Light‐assisted CO₂ Energy Storage

Angewandte Chemie International Edition, Год журнала: 2024, Номер 63(23)

Опубликована: Март 28, 2024

Abstract Visible‐light sensitive and bi‐functionally favored CO 2 reduction (CRR)/evolution (CER) photocathode catalysts that can get rid of the utilization ultraviolet light improve sluggish kinetics is demanded to conquer current technique‐barrier traditional Li‐CO battery. Here, a kind redox molecular junction sp c metal‐covalent organic framework (i.e. Cu 3 ‐BTDE‐COF) has been prepared through connection between BTDE serve as efficient catalyst in light‐assisted ‐BTDE‐COF with redox‐ability, visible‐light‐adsorption region, electron‐hole separation ability endows excellent round‐trip efficiency (95.2 %) an ultralow voltage hysteresis (0.18 V), outperforming Schiff base COFs ‐BTDA‐COF ‐DT‐COF) majority reported catalysts. Combined theoretical calculations characterizations, integration centers, thiazole cyano groups possess strong adsorption/activation Li + interaction/diffusion boost CRR/CER related battery property.

Язык: Английский

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Excited Organic Radicals in Photoredox Catalysis

JACS Au, Год журнала: 2025, Номер 5(2), С. 426 - 447

Опубликована: Янв. 29, 2025

Many important synthetic-oriented works have proposed excited organic radicals as photoactive species, yet mechanistic studies raised doubts about whether they can truly function photocatalysts. This skepticism originates from the formation of (photo)redox-active degradation products and picosecond decay electronically radicals, which is considered too short for diffusion-based photoinduced electron transfer reactions. From this perspective, we analyze synthetic transformations where been photocatalysts, comparing their theoretical maximum state potentials with required observed photocatalytic reactivity. We summarize structurally similar photocatalysts indicating different reaction pathways some catalytic systems, addressing cases radical exceed Additionally, perform a kinetic analysis to explain in on subpicosecond time scales. further rationalize potential anti-Kasha reactivity higher states femtosecond lifetimes, highlighting how future photocatalysis advancements could unlock new photochemical pathways.

Язык: Английский

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Photo- and electro-chemical strategies for the activations of strong chemical bonds

Chemical Society Reviews, Год журнала: 2023, Номер 53(1), С. 263 - 316

Опубликована: Дек. 7, 2023

The employment of light and/or electricity - alternatively to conventional thermal energy unlocks new reactivity paradigms as tools for chemical substrate activations. This leads the development synthetic reactions and a vast expansion spaces. review summarizes recent developments in photo- electrochemical activation strategies functionalization strong bonds particularly carbon-heteroatom (C-X)

Язык: Английский

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Shining Fresh Light on Complex Photoredox Mechanisms through Isolation of Intermediate Radical Anions

ACS Catalysis, Год журнала: 2023, Номер 13(14), С. 9392 - 9403

Опубликована: Июнь 30, 2023

Photoredox catalysis (PRC) has gained enormous and wide-ranging interest in recent years but also been subject to significant mechanistic uncertainty, even controversy. To provide a method by which the missing understanding can begin be filled in, we demonstrate herein that it is possible isolate as authentic materials one-electron reduction products of representative PRC catalysts (PCs). Specifically, KC8 both 9,10-dicyanoanthracene naphthalene monoamide derivative presence cryptand provides convenient access corresponding [K(crypt)+][PC·-] salts clean fully characterized techniques including EPR XRD. Because PC·- states are key intermediates reactions, such isolation allows for highly controlled study these anions' specific reactivity hence their roles. As demonstration this principle, show used conveniently interrogate mechanisms recent, high-profile "conPET" "e-PRC" currently acute Using very simple experiments, able striking insights into reactions' underlying observe surprising levels hidden complexity would otherwise have challenging identify emphasize care control needed when interrogating interpreting mechanisms. These studies foundation far broader range questions around conPET, e-PRC, other reaction future, using same strategy isolation.

Язык: Английский

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A General Photocatalytic Strategy for Nucleophilic Amination of Primary and Secondary Benzylic C–H Bonds

Journal of the American Chemical Society, Год журнала: 2023, Номер 145(33), С. 18487 - 18496

Опубликована: Авг. 11, 2023

We report a visible-light photoredox-catalyzed method that enables nucleophilic amination of primary and secondary benzylic C(sp3)-H bonds. A novel amidyl radical precursor organic photocatalyst operate in tandem to transform bonds into carbocations via sequential hydrogen atom transfer (HAT) oxidative radical-polar crossover. The resulting carbocation can be intercepted by variety N-centered nucleophiles, including nitriles (Ritter reaction), amides, carbamates, sulfonamides, azoles, for the construction pharmaceutically relevant C(sp3)-N under unified reaction conditions. Mechanistic studies indicate HAT is radical-mediated operates reductive quenching pathway. These findings establish mild, metal-free, modular protocol rapid diversification library aminated products.

Язык: Английский

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Electron‐Poor Acridones and Acridiniums as Super Photooxidants in Molecular Photoelectrochemistry by Unusual Mechanisms

Angewandte Chemie International Edition, Год журнала: 2023, Номер 62(44)

Опубликована: Авг. 16, 2023

Abstract Electron‐deficient acridones and in situ generated acridinium salts are reported as potent, closed‐shell photooxidants that undergo surprising mechanisms. When bridging acyclic triarylamine catalysts with a carbonyl group (acridones), this completely diverts their behavior away from open‐shell, radical cationic, ‘beyond diffusion’ photocatalysis to closed‐shell, neutral, diffusion‐controlled photocatalysis. Brønsted acid activation of dramatically increases excited state oxidation power (by +0.8 V). Upon reduction protonated acridones, they transform electron‐deficient even more potent (* E 1/2 =+2.56–3.05 V vs SCE). These oxidize arenes where conventional salt have thusfar been limited electron‐rich arenes. Surprisingly, upon photoexcitation these appear two electron reductive quenching form acridinide anions, spectroscopically‐detected forms. This new behaviour is partly enabled by catalyst preassembly the arene, contrasts SET salts. Critically, study illustrates how redox active chromophoric molecules initially considered photocatalysts can during reaction catalytically species different spectroscopic properties.

Язык: Английский

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Ultraviolet Light Debondable Optically Clear Adhesives for Flexible Displays through Efficient Visible‐Light Curing

Advanced Materials, Год журнала: 2023, Номер 36(14)

Опубликована: Дек. 26, 2023

With growing sustainability concerns, the need for products that facilitate easy disassembly and reuse has increased. Adhesives, initially designed bonding, now face demands selective removal, enabling rapid assembly-disassembly efficient maintenance across industries. This is particularly evident in display industry, with rise of foldable devices necessitating specialized adhesives. A novel optically clear adhesive (OCA) presented display, featuring a unique UV-stimulated removal feature. approach incorporates benzophenone derivatives into polymer network, facilitating debonding under UV irradiation. key feature this method adept use visible-light-driven radical polymerization OCA film fabrication. shows remarkable compatibility various monomers exhibits orthogonal reactivity to benzophenone, rendering it ideal large-scale production. The resultant not only high transparency balanced elasticity, along excellent resistance repeated folding, but also significantly reduced adhesion when exposed By merging customized formulation strategically integrated UV-responsive elements, an effective solution offered enhances manufacturing efficiency product reliability rapidly evolving field sustainable electronics displays. research additionally contributes eco-friendly device fabrication, aligning emerging technology demands.

Язык: Английский

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Lessons learnt in photocatalysis – the influence of solvent polarity and the photostability of the photocatalyst

Chemical Science, Год журнала: 2024, Номер 15(10), С. 3741 - 3757

Опубликована: Янв. 1, 2024

The triplet energies and redox properties of eight photocatalysts were found to vary a function solvent polarity. Irrespective solvent, the photodegraded under PET reaction conditions, but not PEnT conditions.

Язык: Английский

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Generation of holes from intra-valence band for enhanced oxidation potentials under visible light

Chem, Год журнала: 2024, Номер 10(4), С. 1252 - 1267

Опубликована: Фев. 19, 2024

Breaking the trade-off between oxidation potential and spectral response range has been an enduring challenge in field of photocatalysis. Here, we present a general approach to initiating intra-valence band (intra-VB) hole generation organic conjugated molecular crystals under visible light irradiation. The electron-deficient precursor with intrinsically empty side-VB is introduced by Fe3+, enabling electron transition from intra-VB side-VB. By studying five typical photocatalysts, demonstrate that holes strong potentials (up 3.85 V vs. RHE) are generated light. For PTCDA crystals, (HOCO-1 β) couple carbonyl groups, forming hole-coupled sites (–C=O+) extending lifetime 241 times 84.5 ns. Efficient transfer –C=O+ reactants subsequently initiates reactions. high-energy photogenerated exhibit scalable applicability, such as degradation pollutants water natural sunlight.

Язык: Английский

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