Solvated Electrons! The Missing Link in Highly Reducing Photocatalysis

14 September 2022, Version 2
This content is a preprint and has not undergone peer review at the time of posting.


In recent years, in-situ generated organic radicals have been used as highly potent photoinduced electron transfer (PET) agents resulting in catalytic systems as reducing as alkaline metals that can activate remarkably stable bonds. However, the transient nature of these doublet state open-shell species has led to debatable mechanistic studies, hindering adoption and development. Herein, we document the use of an isolated and stable neutral organic radical as a highly photoreducing species with a reduction potential lower than – 3.5 V vs SCE. The isolated radical offers a unique platform to investigate the mechanism behind the photocatalytic activity of organic radicals. Our mechanistic study supports the involvement of solvated electrons formed by single electron transfer (SET) between the short-lived excited state organic radical and the solvent.


ConPET mechanism
Neutral Radical
Isolated [4]helicene radical
aryl halide activation
Two photon excitation
Radical photocatalyst
Potent photoreducing agent
solvated electrons
transient absorption spectroscopy

Supplementary materials

ESI for Isolated Neutral [4]Helicene Radical Provides Insight into Consecutive Two-Photon Excitation Photocatalysis
This document contains the information relevant to the synthesis of the photocatalysts, their characterizations, and the mechanistic studies. As well as the cyclic voltammetry, absorption and emission spectroscopy, the TA and lifetime measurements. The catalytic reaction condition optimizations, catalytic transformations, synthesis of the starting materials and characterization of the catalytic products formed and their spectra are also presented.


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