Visible-Light-Promoted C–S Cross-Coupling via Intermolecular Charge Transfer

Journal of the American Chemical Society, Год журнала: 2017, Номер 139(39), С. 13616 - 13619

Опубликована: Сен. 14, 2017

Disclosed is a mild, scalable, visible-light-promoted cross-coupling reaction between thiols and aryl halides for the construction of C–S bonds in absence both transition metal photoredox catalysts. The scope thiol partners includes over 60 examples therefore provides an entry point into various thioether building blocks pharmaceutical interest. Furthermore, to demonstrate its utility, this coupling protocol was applied drug synthesis late-stage modifications active ingredients. UV–vis spectroscopy time-dependent density functional theory calculations suggest that intermolecular charge transfer within thiolate–aryl halide electron donor–acceptor complex permits reactivity catalyst.

Язык: Английский

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Externally controlled atom transfer radical polymerization

Chemical Society Reviews, Год журнала: 2018, Номер 47(14), С. 5457 - 5490

Опубликована: Янв. 1, 2018

ATRP can be externally controlled by electrical current, light, mechanical forces and various chemical reducing agents. The mechanistic aspects preparation of polymers with complex functional architectures their applications are critically reviewed.

Язык: Английский

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Photons or Electrons? A Critical Comparison of Electrochemistry and Photoredox Catalysis for Organic Synthesis

Chemical Reviews, Год журнала: 2021, Номер 122(2), С. 2487 - 2649

Опубликована: Ноя. 9, 2021

Redox processes are at the heart of synthetic methods that rely on either electrochemistry or photoredox catalysis, but how do and catalysis compare? Both approaches provide access to high energy intermediates (e.g., radicals) enable bond formations not constrained by rules ionic 2 electron (e) mechanisms. Instead, they 1e mechanisms capable bypassing electronic steric limitations protecting group requirements, thus enabling chemists disconnect molecules in new different ways. However, while providing similar intermediates, differ several physical chemistry principles. Understanding those differences can be key designing transformations forging disconnections. This review aims highlight these similarities between comparing their underlying principles describing impact electrochemical photochemical methods.

Язык: Английский

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Atom Transfer Radical Polymerization: Billion Times More Active Catalysts and New Initiation Systems

Macromolecular Rapid Communications, Год журнала: 2018, Номер 40(1)

Опубликована: Окт. 30, 2018

Approaching 25 years since its invention, atom transfer radical polymerization (ATRP) is established as a powerful technique to prepare precisely defined polymeric materials. This perspective focuses on the relation between structure and activity of ATRP catalysts, consequent choice initiating system, which are paramount aspects well-controlled polymerizations. The mechanism discussed, including effect kinetic thermodynamic parameters side reactions affecting catalyst. coordination chemistry copper complexes used in reviewed chronological order, while emphasizing structure-activity correlation. ATRP-initiating systems described, from normal low ppm Cu systems. Most recent advancements regarding dispersed media oxygen-tolerant techniques presented, well future opportunities that arise progressively more active catalysts deeper mechanistic understanding.

Язык: Английский

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Highly Conjugated Three-Dimensional Covalent Organic Frameworks Based on Spirobifluorene for Perovskite Solar Cell Enhancement

Journal of the American Chemical Society, Год журнала: 2018, Номер 140(31), С. 10016 - 10024

Опубликована: Июль 14, 2018

Highly conjugated three-dimensional covalent organic frameworks (3D COFs) were constructed based on spirobifluorene cores linked via imine bonds (SP-3D-COFs) with novel interlacing conjugation systems. The crystalline structures confirmed by powder X-ray diffraction and detailed structural simulation. A 6- or 7-fold interpenetration was formed depending the structure of linking units. obtained SP-3D-COFs showed permanent porosity high thermal stability. In application for solar cells, simple bulk doping to perovskite cells (PSCs) substantially improved average power conversion efficiency 15.9% SP-3D-COF 1 18.0% 2 as compared reference undoped PSC, while offering excellent leakage prevention in meantime. By aid both experimental computational studies, a possible photoresponsive perovskite–SP-3D-COFs interaction mechanism proposed explain improvement PSC performance after doping.

Язык: Английский

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Photoinduced Organocatalyzed Atom Transfer Radical Polymerization (O-ATRP): Precision Polymer Synthesis Using Organic Photoredox Catalysis

Chemical Reviews, Год журнала: 2021, Номер 122(2), С. 1830 - 1874

Опубликована: Ноя. 29, 2021

The development of photoinduced organocatalyzed atom transfer radical polymerization (O-ATRP) has received considerable attention since its introduction in 2014. Expanding on many the advantages traditional ATRP, O-ATRP allows well-defined polymers to be produced under mild reaction conditions using organic photoredox catalysts. As a result, opened access range sensitive applications where use metal catalyst could concern, such as electronics, certain biological applications, and coordinating monomers. However, key limitations this method remain necessitate further investigation continue field. such, review details achievements made to-date well future research directions that will expand capabilities application landscape O-ATRP.

Язык: Английский

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Structure–Property Relationships for Tailoring Phenoxazines as Reducing Photoredox Catalysts

Journal of the American Chemical Society, Год журнала: 2018, Номер 140(15), С. 5088 - 5101

Опубликована: Март 7, 2018

Through the study of structure–property relationships using a combination experimental and computational analyses, number phenoxazine derivatives have been developed as visible light absorbing, organic photoredox catalysts (PCs) with excited state reduction potentials rivaling those highly reducing transition metal PCs. Time-dependent density functional theory (TD-DFT) modeling photoexcitation N-aryl core modified phenoxazines guided design PCs absorption profiles in regime. In accordance our previous work N,N-diaryl dihydrophenazines, characterization noncore demonstrated that nature substituent dictates ability PC to access charge transfer state. However, current analysis revealed these molecules can different type CT which we posit involves electron acceptor. Modification electron-donating electron-withdrawing substituents was used alter triplet energies, potentials, oxidation derivatives. The catalytic activity explored organocatalyzed atom radical polymerization (O-ATRP) for synthesis poly(methyl methacrylate) (PMMA) white irradiation. All were determined be suitable O-ATRP indicated by linear growth polymer molecular weight function monomer conversion synthesize PMMA moderate low dispersity (dispersity less than or equal 1.5) initiator efficiencies typically greater 70% at high conversions. only exhibit strong maintain control over during entire course reaction. established here will enable application other photoredox-catalyzed small molecule syntheses.

Язык: Английский

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Selective C–F Functionalization of Unactivated Trifluoromethylarenes

Journal of the American Chemical Society, Год журнала: 2019, Номер 141(33), С. 13203 - 13211

Опубликована: Авг. 1, 2019

Fluorinated organic molecules are pervasive within the pharmaceutical and agrochemical industries due to range of structural physicochemical properties that fluorine imparts. Currently, most abundant methods for synthesis aryl–CF2 functionality have relied on deoxyfluorination ketones aldehydes using expensive poorly atom economical reagents. Here, we report a general method aryl–CF2R aryl–CF2H compounds through activation corresponding trifluoromethyl arene precursors. This strategy is enabled by an endergonic electron transfer event provides access radical anions lie outside catalyst reduction potential. Fragmentation these reactive intermediates delivers difluorobenzylic radicals can be intercepted alkene feedstocks or hydrogen provide diverse array difluoalkylaromatics.

Язык: Английский

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Intramolecular Charge Transfer and Ion Pairing in N,N-Diaryl Dihydrophenazine Photoredox Catalysts for Efficient Organocatalyzed Atom Transfer Radical Polymerization

Journal of the American Chemical Society, Год журнала: 2016, Номер 139(1), С. 348 - 355

Опубликована: Дек. 14, 2016

Photoexcited intramolecular charge transfer (CT) states in N,N-diaryl dihydrophenazine photoredox catalysts are accessed through catalyst design and investigated combined experimental studies density functional theory (DFT) calculations. These CT reminiscent of the metal to ligand (MLCT) ruthenium iridium polypyridyl complexes. For cases where polar state is lowest energy excited state, we observe its population significant solvatochromic shifts emission wavelength across visible spectrum by varying solvent polarity. We propose importance accessing for catalysis atom radical polymerization lies their ability minimize fluorescence while enhancing electron rates between photoexcited substrate. Additionally, polarity influences deactivation pathway, greatly affecting strength ion pairing oxidized photocatalyst bromide anion thus realize a controlled polymerization. Greater understanding these with respect enables application toward methyl methacrylate synthesis polymers precisely tunable molecular weights dispersities typically lower than 1.10.

Язык: Английский

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Strongly Reducing, Visible‐Light Organic Photoredox Catalysts as Sustainable Alternatives to Precious Metals

Chemistry - A European Journal, Год журнала: 2017, Номер 23(46), С. 10962 - 10968

Опубликована: Июнь 27, 2017

Abstract Photoredox catalysis is a versatile approach for the construction of challenging covalent bonds under mild reaction conditions, commonly using photoredox catalysts (PCs) derived from precious metals. As such, there need to develop organic analogues as sustainable replacements. Although several PCs have been introduced, remains lack strongly reducing, visible‐light PCs. Herein, we establish critical photophysical and electrochemical characteristics both dihydrophenazine phenoxazine system that enables their success trifluoromethylation reactions dual photoredox/nickel‐catalyzed C−N C−S cross‐coupling reactions, which historically exclusive metal

Язык: Английский

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