1416881-52-1Relevant articles and documents
Luminescent solar concentrators based on thermally activated delayed fluorescence dyes
Hong, Sung-Kyu,Lee, Sae Youn,Mateen, Fahad
, p. 3708 - 3716 (2020)
Thermally activated delayed fluorescence (TADF) dyes are third-generation light emitting materials. With impressive photophysical properties, TADF dyes are now widely recognized as successful emitters in organic light emitting diodes (OLEDs). However, their use in photovoltaic applications has not been realized. In this study, we for the first time present a TADF dye based luminescent solar concentrator device for efficient sunlight harvesting. We synthesized two carbazole dicyanobenzene (CDCB) derivative dyes and employed them in a bulk LSC device. Due to the charge transfer characteristics and twisted structures, TADF dyes help to achieve reduced reabsorption losses in the LSC. The photovoltaic measurements showed that the optical conversion efficiency (ηopt) and power conversion efficiency (ηPCE) of the champion device are 10.4% and 2.2%, respectively. Additionally, the superior resistance against photodegradation of TADF dyes facilitates their long-term use in LSCs. The results demonstrate that TADF dye-based LSCs provide a promising route for high-efficiency and low-cost solar energy generation.
Photocatalytic intermolecular carboarylation of alkenes by selective C-O bond cleavage of diarylethers
Ji, Meishan,Chang, Chenyang,Wu, Xinxin,Zhu, Chen
, p. 9240 - 9243 (2021)
Disclosed herein is a novel radical-mediated intermolecular carboarylation of alkenes by cleaving inert C-O bonds. The strategically designed arylbenzothiazolylether diazonium salts are harnessed as dual-function reagents. A vast array of alkenes are proven to be suitable substrates. The benzothiazolyl moiety in the products serves as the formyl precursor, and the OH residue provides the cross-coupling site for further product elaboration, indicating the robust transformability of the products.
Development of Thermally Activated Delayed Fluorescence Materials with Shortened Emissive Lifetimes
Kretzschmar, Andreas,Patze, Christian,Schwaebel, S. Thimon,Bunz, Uwe H. F.
, p. 9126 - 9131 (2015)
We have prepared a thermally activated delayed fluorescence (TADF) capable molecular system carrying halogen substituents at the carbazole units. The attachment of the halogen atoms considerably decreases the half-life of the delayed fluorescence. The effect is significant. The heavier the halogen, the greater the effect. Our materials have the shortest reported emissive lifetimes for TADF achieved to date. Intersystem crossing (ISC) is improved through the heavy atom effect, yet high quantum yields are achieved both in solution as well as in thin doped films. The simple and efficient synthesis of our targets uses inexpensive and easily obtained starting materials.
Visible-light-initiated 4CzIPN catalyzed multi-component tandem reactions to assemble sulfonated quinoxalin-2(1H)-ones
Wang, Zhiwei,Liu, Qishun,Liu, Ruisheng,Ji, Zhongyin,Li, Yan,Zhao, Xiaohui,Wei, Wei
supporting information, p. 1479 - 1482 (2021/09/06)
A mild and efficient photochemical multi-component tandem reaction of quinoxalin-2(1H)-ones, alkenes and sulfinic acids is reported. This tandem reaction could be conveniently carried out at room temperature by employing 4CzIPN as the metal-free photocata
Solvent-Minimized Synthesis of 4CzIPN and Related Organic Fluorophores via Ball Milling
Leitch, Jamie A.,Smallman, Harry R.,Browne, Duncan L.
supporting information, p. 14095 - 14101 (2021/07/31)
The mechanochemical synthesis of 2,4,5,6-tetra(9H-carbazol-9-yl)isophthalonitrile and related organic fluorophores/photocatalysts via a solvent-minimized four-fold SNAr pathway is herein described. Employing sodium tert-butoxide as base, and negating the need for any air/moisture-sensitive reaction set-ups, a selection of organic dyes was synthesized in just 1 h using this ball-milling technique. Furthermore, the transformation was then showcased on a multigram scale.
A Unified Strategy to Access 2- And 4-Deoxygenated Sugars Enabled by Manganese-Promoted 1,2-Radical Migration
Carder, Hayden M.,Suh, Carolyn E.,Wendlandt, Alison E.
supporting information, p. 13798 - 13805 (2021/09/07)
The selective manipulation of carbohydrate scaffolds is challenging due to the presence of multiple, nearly chemically indistinguishable O-H and C-H bonds. As a result, protecting-group-based synthetic strategies are typically necessary for carbohydrate modification. Here we report a concise semisynthetic strategy to access diverse 2- and 4-deoxygenated carbohydrates without relying on the exhaustive use of protecting groups to achieve site-selective reaction outcomes. Our approach leverages a Mn2+-promoted redox isomerization step, which proceeds via sugar radical intermediates accessed by neutral hydrogen atom abstraction under visible light-mediated photoredox conditions. The resulting deoxyketopyranosides feature chemically distinguishable functional groups and are readily transformed into diverse carbohydrate structures. To showcase the versatility of this method, we report expedient syntheses of the rare sugars l-ristosamine, l-olivose, l-mycarose, and l-digitoxose from commercial l-rhamnose. The findings presented here validate the potential for radical intermediates to facilitate the selective transformation of carbohydrates and showcase the step and efficiency advantages attendant to synthetic strategies that minimize a reliance upon protecting groups.
SELECTIVE VALORIZATION OF BIOMASS SUGARS
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Page/Page column 23; 28-29, (2021/06/26)
Disclosed are methods of forming an epimer or a dehydrated isomer of a pyranose monosaccharide or a pyranose saccharide residue in an oligosaccharide or a glycoside.
Late Stage Phosphotyrosine Mimetic Functionalization of Peptides Employing Metallaphotoredox Catalysis
Brzozowski, Martin,Chen, Hao,Mao, Runyu,Nguyen, Nghi H.,Sleebs, Brad E.
supporting information, p. 4244 - 4249 (2021/06/28)
Access to phosphotyrosine (pTyr) mimetics requires multistep syntheses, and therefore late stage incorporation of these mimetics into peptides is not feasible. Here, we develop and employ metallaphotoredox catalysis using 4-halogenated phenylalanine to afford a variety of protected pTyr mimetics in one step. This methodology was shown to be tolerant of common protecting groups and applicable to the late stage pTyr mimetic modification of protected and unprotected peptides, and peptides of biological relevance.
Non-innocent Radical Ion Intermediates in Photoredox Catalysis: Parallel Reduction Modes Enable Coupling of Diverse Aryl Chlorides
Chernowsky, Colleen P.,Chmiel, Alyah F.,Wickens, Zachary K.,Williams, Oliver P.,Yeung, Charles S.
supporting information, p. 10882 - 10889 (2021/07/31)
We describe a photocatalytic system that elicits potent photoreductant activity from conventional photocatalysts by leveraging radical anion intermediates generated in situ. The combination of an isophthalonitrile photocatalyst and sodium formate promotes diverse aryl radical coupling reactions from abundant but difficult to reduce aryl chloride substrates. Mechanistic studies reveal two parallel pathways for substrate reduction both enabled by a key terminal reductant byproduct, carbon dioxide radical anion.
Electrochemical Activation of Diverse Conventional Photoredox Catalysts Induces Potent Photoreductant Activity**
Chernowsky, Colleen P.,Chmiel, Alyah F.,Wickens, Zachary K.
supporting information, p. 21418 - 21425 (2021/08/25)
Herein, we disclose that electrochemical stimulation induces new photocatalytic activity from a range of structurally diverse conventional photocatalysts. These studies uncover a new electron-primed photoredox catalyst capable of promoting the reductive cleavage of strong C(sp2)?N and C(sp2)?O bonds. We illustrate several examples of the synthetic utility of these deeply reducing but otherwise safe and mild catalytic conditions. Finally, we employ electrochemical current measurements to perform a reaction progress kinetic analysis. This technique reveals that the improved activity of this new system is a consequence of an enhanced catalyst stability profile.
