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meso-methyl-BODIPY photocages release a leaving group upon visible light irradiation but often lack thermal stability. In turn, our thermally-stable, red-shifted BODIPY phototether allows oligonucleotide cyclization, preventing complementary strand hybridization. Hybridization resumes upon red-NIR irradiation, disconnecting the phototether by oxidative cleavage, which is easily monitored by a blue shift in fluorescence. [ABSTRACT FROM AUTHOR]

N‐Trifluoromethylated organics may be applied in drug design, agrochemical synthesis, and materials science, among other areas. Yet, despite recent advances in the synthesis of aliphatic, cyclic and heterocyclic N‐trifluoromethyl compounds, no strategy based on trifluoromethyl nitrene has hitherto been explored. Here we describe the formation of triplet trifluoromethyl nitrene from azidotrifluoromethane, a stable and safe‐to‐use precursor, by visible light photocatalysis. The addition of CF3N to alkenes via biradical intermediates afforded previously unknown aziridines substituted with trifluoromethyl group on the nitrogen atom. The obtained aziridines were converted into either N‐trifluoromethylimidazolines, via formal [3+2] cycloaddition with nitriles, mediated by a Lewis acid, or into N‐trifluoromethylaldimines, via ring opening and aryl group migration mediated by a strong Brønsted acid. Our findings open new opportunities for the development of novel classes of N‐CF3 compounds with possible applications in the life sciences. [ABSTRACT FROM AUTHOR]

A fulgide photoswitch is presented as a novel actinometer for a broad range of wavelengths from the UV to the NIR region (340–700 nm). It is easily accessible and has a robust photochemistry and high fatigue resistance. Its photophysics and photochemistry are described in detail. Quantum yields of photoswitching were measured for a series of wavelengths and standardized against known standards (ferrioxalate actinometry, calibrated photodiode). We also present a method for the precise determination of photoswitching quantum yields by global analysis of the whole spectra and an alternative quick and easy method for rapid determination of photon fluxes. [ABSTRACT FROM AUTHOR]

To date, most known molecules that release carbon monoxide by the action of light are based on carbonyl complexes of metals. However, they suffer from several disadvantages, so the focus of this perspective is on photoactivatable metal-free CO precursors. The development and design of these systems from the starting point of deep-UV-absorbing hydrophobic molecules and leading to hydrophilic biocompatible visible-light-absorbing CO-releasing molecules (photoCORMs) is described with mechanistic details for several structural motifs. The possibilities of this development are not exhausted and here we discuss the design of new biologically interesting candidates. [ABSTRACT FROM AUTHOR]

Abstract: New photocatalysts from the flavin family were found to mediate the [2+2] photocycloaddition reaction. 3‐Butyl‐10‐methyl‐5‐deazaflavin (3 a) and 1‐butyl‐7,8‐dimethoxy‐3‐methylalloxazine (2 e), if irradiated by visible light, were shown to allow an efficient (Φ≈3–10 %) intramolecular cyclisation of various types of substrates including substituted styrene dienes and bis(aryl enones), considered as electron‐rich and electron‐poor substrates, respectively, without any additional reagent. The versatility of the procedure was demonstrated by the cyclisation of photosensitive cinnamyl (E)‐3‐iodoallyl ether. Structure–activity studies found alloxazine 2 e was more active than 7‐monosubstituted (R=Cl, Br and MeO) alloxazines. The introduction of chlorine and bromine atom on the deazaflavin skeleton did not enhance the catalytic efficiency of 3 a. A detailed electrochemical and spectroscopic study explains the reaction mechanism proceeding through energy transfer from the flavin excited triplet state to the diene followed by its cyclisation. [ABSTRACT FROM AUTHOR]