A multidisciplinary team of researchers led by Dr Ludovic Troian-Gautier (Université Catholique de Louvain) have published a study on the mechanism of photoredox reactions involving aryl diazonium salts and a range of photosensitisers.

Photoredox catalysis is a powerful approach that uses light to unlock new molecular synthesis pathways, in this case borylation of aryldiazonium to form a C – B bond. Light excites a photosensitiser molecule which transfers an electron to the substrate molecule. The resulting pair of radicals can then recombine or escape their solvent cage to generate reaction products. Understanding the mechanism of the reaction is essential to optimise its conditions and maximise its yield. This is what Dr Troian-Gautier’s team set out to do, using a combination of different reaction schemes and spectroscopic techniques.

Using the LP980 transient absorption spectrometer from Edinburgh Instruments, the team detected the transient pair of radicals formed in the process and the lifetime of the reaction intermediates, as well as the corresponding cage escape yield which determines the efficiency of the reaction. Their results shed light on the excited state reactivity of diazonium salts and pave the way for implementing these synthetic approaches in industry.

Download the full article: Photosensitized activation of diazonium derivatives for C-B bond formation