Visible Light Photoredox Catalysis with Transition Metal Complexes: Applications in Organic Synthesis

Sulfonylative and Azidosulfonylative Cyclizations by Visible‐Light‐Photosensitization of Sulfonyl Azides in THF

“…Single‐electron‐transfer to organic azides has been postulated in photocatalytic reactions 4a,4i. However, the reduction potential E 1/2 red of para ‐toluenesulfonyl azide ( 2 a ) was measured by cyclic voltammetry to be −1.22 V versus SCE in MeCN,12 and it would appear that the photoexcited states of the iridium complexes Ir 1 – 3 are insufficiently reducing to promote this electron transfer efficiently ( Ir 1 , E * III/IV =−0.96 V vs. SCE;3e Ir 2 , E * III/IV =−0.85 V vs. SCE,13 and Ir 3 , E * III/IV =−0.89 V vs. SCE3e). The superiority of THF over other solvents is also not readily explained by an electron transfer mechanism.…”

A Fully Automated Continuous‐Flow Platform for Fluorescence Quenching Studies and Stern–Volmer Analysis

“…In photoredox reactions, the ability of a photocatalyst to absorb visible light, reach an excited state and ultimately engage in a single electron transfer (SET) with an organic substrate is exploited as a powerful trigger to induce selective and unique transformations 1a, 2. In this context, a great deal of effort has been devoted to the understanding of the photophysical and photochemical aspects governing SET processes 3.…”

“…In other words, a photocatalyst dissipates the energy acquired through light absorption by either emitting light or heat. However, in presence of an organic molecule that can act as either energy acceptor or electron donor/acceptor, energy dissipation is averted and a productive transfer can occur, thus generating radical species of interest 1a. Therefore, observing a decrease in the emission of an excited photocatalyst can be considered as a tangible proof of its interaction with an organic substrate and is the principle on which fluorescence quenching studies are based 5…”

A Non‐Heme Iron Photocatalyst for Light‐Driven Aerobic Oxidation of Methanol

“…Photoredox catalysis has emerged as a versatile method to access highly reactive species in a selective and clean manner 1, 2. The redox‐active photosensitizers available include organic dyes,3 inorganic clusters,4 and transition‐metal complexes, such as [Ru(bpy) 3 ] 2+ and its derivatives,5, 6 whose redox potentials can be fine‐tuned by ligand modification 7, 8, 9.…”