Organic compounds that show Thermally Activated Delayed Fluorescence (TADF) have become wildly popular as next-generation emitters in organic light emitting diodes (OLEDs). Since 2016, a subset of these have found increasing use as photocatalysts. This review comprehensively highlights their potential by documenting the diversity of the reactions where an organic TADF photocatalyst can be used in lieu of a noble metal complex photocatalyst. Beyond the small number of TADF photocatalysts that have been used to date, the analysis conducted within this review reveals the wider potential of organic donor–acceptor TADF compounds as photocatalysts. A discussion of the benefits of compounds showing TADF for photocatalysis is presented, which paints a picture of a very promising future for organic photocatalyst development.

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Organic thermally activated delayed fluorescence (TADF) compounds used in photocatalysis

We have calculated the optical structure of wurtzite ZnO doped with Silicon (Si). The calculations are based on the density functional theory with the generalized gradient approximation (GGA) and the projector augmented wave pseudopotentials. The GGA with the Perdew Burke Ernzerhof exchange-correlation functional are employed in the simulations. Ultrasoft pseudopotentials are utilized for the geometry optimization to render the computations tractable as well as to enhance the efficiency. We investigate two kinds of defects in ZnO, namely the substitution of Zn by Si and O by Si. The optical properties, including dielectric function, reflectivity and absorption coefficient of wurtzite ZnO are calculated. The variation in the band gap and energetics have been validated against published results. The dielectric properties follow a steep decreasing trend for the low energy level. In addition, the reflectivity and absorption coefficients reduce abruptly due to the doping.

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Optical properties of silicon doped ZnO

The visible light harnessing ability of Rose Bengal, an organic dye, has been extensively employed in organic chemistry over the last few years. In visible light mediated reactions, this photoredox catalyst operates through multiple pathways and has the ability to provide distinctly different and valuable results. The most significant of these results are bond creation, bond functionalization, particularly for C–H and C–heteroatom bonds, and cross couplings. It is crucial to study these cases whenever these bond formations and couplings lead to the formation of heterocyclic compounds or their functionalization. The diverse biological activity and medicinal applications of heterocyclic compounds is an extensively explored area. This review primarily attempts to demonstrate the synthetic potential of Rose Bengal for synthesis and site selective functionalization of nitrogen containing heterocycles.

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Recent applications of Rose Bengal catalysis in N-heterocycles: a short review

Recent Developments in Photo-Catalyzed/Promoted Synthesis of Indoles and Their Functionalization: Reactions and Mechanisms

Disulfides are versatile catalysts. They can be photocatalysts, hydrogen atom transfer (HAT) catalysts, cocatalysts, or initiators in photocatalytic reactions. Under photoirradiation, organic disulfides can be easily cleaved into free thiyl radicals (RS•) and can reversibly add to unsaturated multiple bonds to catalyze a variety of functionalization reactions under mild conditions. In photoredox catalysis reactions, an excellent electron transfer ability and excellent radical properties also made these thiyl radicals powerful HAT catalysts. They have increasingly been proven useful in various types of organic photoreactions, such as cyclizations, anti-Markovnikov additions, aromatic olefin carbonylations, isomerizations, etc. They are a class of green, economic, mild, and chemoselective radical catalysts that deserve more attention. The present review highlights the recent progress in the field of disulfide-catalyzed and -cocatalyzed photocatalytic reactions for different reaction types.

https://www.beilstein-journals.org/bjoc/content/pdf/1860-5397-16-118.pdf

An overview on disulfide-catalyzed and -cocatalyzed photoreactions.

A novel and facile visible-light-mediated alkylation of indoles and nitroalkenes has been developed. In this protocol, rose bengal acts as a photosensitizer, and environmentally benign water was used as the green and efficient reaction medium. Indoles reacted smoothly with nitroalkenes under the irradiation of visible-light and generated corresponding 3-(2-nitroalkyl)indoles in moderate to good yields (up to 87%).

/pdf/rose-bengal-as-photocatalyst-visible-light-mediated-friedel-1xv76lrh24.pdf

Rose bengal as photocatalyst: visible light-mediated Friedel–Crafts alkylation of indoles with nitroalkenes in water

Visible light-mediated selective α-functionalization of 1,3-dicarbonyl compounds via disulfide induced aerobic oxidation

A sustainable and practical protocol to prepare epoxides has been established by using air as the oxidant in the presence of K2CO3 in isopropylbenzene (CM) at 80–140 °C. The olefins are successfull...

Cunfei Ma

Papers

Rose bengal as photocatalyst: visible light-mediated Friedel–Crafts alkylation of indoles with nitroalkenes in water

Visible light-mediated selective α-functionalization of 1,3-dicarbonyl compounds via disulfide induced aerobic oxidation

Sustainable and Practical Access to Epoxides: Metal-Free Aerobic Epoxidation of Olefins Mediated by Peroxy Radical Generated In Situ

Selective Oxidation of Benzylic sp3 C–H Bonds using Molecular Oxygen in a Continuous-Flow Microreactor

Ab initio investigations on the electronic structure and optical properties of HX-ZnO