High‐Quality Whispering‐Gallery‐Mode Lasing from Cesium Lead Halide Perovskite Nanoplatelets

Advanced Functional Materials, Journal Year: 2016, Volume and Issue: 26(34), P. 6238 - 6245

Published: July 1, 2016

Semiconductor micro/nano‐cavities with high quality factor (Q) and small modal volume provide critical platforms for exploring strong light‐matter interactions quantum optics, enabling further development of coherent photonic devices. Constrained by exciton binding energy thermal fluctuation, only a handful wide‐band semiconductors such as ZnO GaN have stable excitons at room temperature. Metal halide perovskite cubic lattice well‐controlled may solutions. In this work, high‐quality single‐crystalline cesium lead CsPbX 3 (X = Cl, Br, I) whispering‐gallery‐mode (WGM) microcavities are synthesized vapor‐phase van der Waals epitaxy method. The as‐grown perovskites show emission temperature over the whole visible spectra range. By varying composition, multi‐color (400–700 nm).WGM excitonic lasing is achieved low threshold (~ 2.0 μJ cm −2 ) coherence (~0.14–0.15 nm). results advocate promise inorganic towards optoelectronic devices coupling in optics.

Language: Английский

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Transition-Metal (Cu, Pd, Ni)-Catalyzed Difluoroalkylation via Cross-Coupling with Difluoroalkyl Halides

Accounts of Chemical Research, Journal Year: 2018, Volume and Issue: 51(9), P. 2264 - 2278

Published: Aug. 22, 2018

Difluoroalkylated compounds play a remarkably important role in life and materials sciences because of the unique characteristics difluoromethylene (CF2) group. In particular, precise introduction CF2 group at benzylic position can dramatically improve biological properties corresponding molecules. As consequence, difluoroalkylation aromatic has become powerful strategy modulating bioactivities organic However, efficient strategies to selectively synthesize difluoroalkylated arenes had been very limited before 2012. Traditional synthetic methods this regard suffer from either harsh reaction conditions or narrow substrate scope, significantly restricting their widespread applications, particularly for late-stage bioactive To overcome these limitations, straightforward route access valuable skeletons is direct (CF2R) onto rings through transition-metal-catalyzed cross-coupling. instability some metal species, which are prone protonation, dimerization, and/or generation other unknown byproducts, it difficult control catalytic cycle suppress side reactions. context, we proposed use low-cost widely available difluoroalkyl halides as fluoroalkyl sources reactions via Account, summarize our major efforts on copper-, palladium-, nickel-catalyzed difluoroalkylations aromatics with sources. Four modes reactions, including nucleophilic difluoroalkylation, electrophilic radical metal-difluorocarbene coupling (MeDiC), have demonstrated careful modulation systems. Among MeDiC represents new mode fluoroalkylation. These processes enable variety aryl arylboron reagents under mild conditions. A wide range halides, activated (Cl/BrCF2R, R = π system), unactivated (BrCF2R, alkyl, H), especially inert inexpensive industrial chemical chlorodifluoromethane (ClCF2H), applicable providing facile routes diverse (hetero)arenes. halide-based also be applied prepare alkenes, alkynes, alkanes feature impressive advantages over conventional synthesis terms efficiency, functional tolerance, structural diversity. molecules offers good opportunities development medicinal agents without need multistep de novo syntheses.

Language: Английский

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Flexibility Matters: Cooperative Active Sites in Covalent Organic Framework and Threaded Ionic Polymer

Journal of the American Chemical Society, Journal Year: 2016, Volume and Issue: 138(48), P. 15790 - 15796

Published: Nov. 17, 2016

The combination of two or more reactive centers working in concert on a substrate to facilitate the reaction is now considered state art catalysis, yet there still remains tremendous challenge. Few heterogeneous systems this sort have been exploited, as active sites spatially separated within rigid framework are usually difficult cooperate. It shown that roadblock can be surpassed. underlying principle strategy presented here integration catalytic components with excellent flexibility and porous catalysts, demonstrated by placement linear ionic polymers close proximity surface Lewis acid anchored walls covalent organic (COF). Using cycloaddition epoxides CO2 model reaction, dramatic activity improvements achieved for composite catalysts relation individual component. Furthermore, they also clearly outperform benchmark formed molecular organocatalysts while affording additional recyclability. extraordinary enriched concentration catalytically moieties concerted thus leading superior performance. This work therefore uncovers an entirely new designing bifunctional double-activation behavior opens avenue design multicapable mimic biocatalysis.

Language: Английский

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Difluoromethylation Reactions of Organic Compounds

Chemistry - A European Journal, Journal Year: 2017, Volume and Issue: 23(59), P. 14676 - 14701

Published: June 20, 2017

Abstract The relevance of the ‐CF 2 H moiety has attracted considerable attention from organic synthetic and medicinal chemistry communities, because this group can act as a more lipophilic isostere carbinol, thiol, hydroxamic acid, or amide groups. Being weakly acidic, CF establish hydrogen‐bonding interactions to improve binding selectivity biologically active compounds. Therefore, hydroxyl, amino, thio substituents lead structures are routinely replaced by motif in drug discovery, with great benefits pharmacological activity drugs candidates agrochemicals. Consequently, late‐stage introduction is sought‐after strategy designing bioactive Secondly, but nonetheless relevant meaningful, study pathways introduce −Y (Y≠H, F) into substrates compounds that contain functionality have also found vast applications other areas, such fungicides, insecticides, etc., thus, deserves special attention. Although emphasis made on difluoromethylation strategies functionalize different families compounds, three main methodological protocols will be presented review article for Y moieties substrates: i) metal‐photoredox catalysis; ii) through transition metal‐catalyzed thermal protocols; iii) transition‐metal‐free strategies.

Language: Английский

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Bimetallic catalysis for C–C and C–X coupling reactions

Chemical Science, Journal Year: 2017, Volume and Issue: 8(3), P. 1705 - 1718

Published: Jan. 1, 2017

Bimetallic catalysis represents an alternative paradigm for coupling chemistry that complements the more traditional single-site approach.

Language: Английский

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Recent Progress toward the Introduction of Functionalized Difluoromethylated Building Blocks onto C(sp²) and C(sp) Centers

Chemistry - A European Journal, Journal Year: 2015, Volume and Issue: 21(37), P. 12836 - 12865

Published: July 14, 2015

Fluorine chemistry is a field undergoing tremendous expansion. Although much attention has been paid to the introduction of fluorine atom and CF3 group, less interest devoted functionalized fluorinated building blocks, in sharp contrast with high versatility products. In this Minireview, most relevant methods for difluoromethylated blocks are summarized. Access arenes, alkenes, alkynes highlighted special explanation reaction mechanism.

Language: Английский

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Synergistic Dual Transition Metal Catalysis

Chemical Reviews, Journal Year: 2020, Volume and Issue: 120(24), P. 13382 - 13433

Published: Nov. 29, 2020

Synergistic catalysis, a type of plural catalysis which utilizes at least two different catalysts to enable reaction between separately activated substrates, has unlocked plethora previously unattainable transformations and novel chemical reactivity. Despite the appreciable utility synergistic specific examples involving transition metals have been limited, as ensuring judicious choice parameters prevent deactivation catalysts, undesirable monocatalytic event(s) leading side products, or premature termination other potentially troublesome outcomes present formidable challenge. Excluding those driven by photocatalytic mechanisms, this review will highlight reported reactions that make use simultaneous catalytic cycles metal catalysts.

Language: Английский

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Chlorodifluoromethane-triggered formation of difluoromethylated arenes catalysed by palladium

Nature Chemistry, Journal Year: 2017, Volume and Issue: 9(9), P. 918 - 923

Published: March 13, 2017

Language: Английский

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Late-stage difluoromethylation: concepts, developments and perspective

Chemical Society Reviews, Journal Year: 2021, Volume and Issue: 50(14), P. 8214 - 8247

Published: Jan. 1, 2021

This review describes the conceptual advances that have led to multiple difluoromethylation processes making use of well-defined CF₂H sources.

Language: Английский

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Metal‐Catalyzed Direct Difluoromethylation Reactions

Asian Journal of Organic Chemistry, Journal Year: 2016, Volume and Issue: 6(2), P. 139 - 152

Published: Dec. 19, 2016

Abstract Owing to the excellent performance of fluorinated compounds in areas pharmaceuticals, agrochemicals, and materials chemistry, organic chemists have made great efforts towards selective incorporation fluorine or moieties into molecules through nucleophilic, electrophilic, radical, metal‐catalyzed pathways. Impressive progress fluorination perfluoroalkylation (especially trifluoromethylation) reactions has been over past few decades. However, methods for incorporating lightly groups (such as −CF 2 H) are still underdeveloped, spite their important applications pharmaceuticals agrochemicals. This Focus Review summarizes recent developments direct difluoromethylation reactions.

Language: Английский

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