Session: Photoredox Chemistry:

Introduction of peripheral amine groups to the simple triaryl carbenium system furnished a class of electron rich Acridinium series. Acridiniums are well known in the field of photocatalysis, mostly due to their robust photooxidation reactions in presence of blue lights. But this new acridinium family can initiate photo reductive reactions under green light besides their usual photooxidation reactions. Gratifyingly, this reducing ability can reach up to the reduction potential of -2.00 V in the photoexcited state under both green light (λ = 518 nm) and regular household white LED. Therefore, this acridinium series has been employed to activate the C(sp²)-X bond in the aryl halides. To our delight, successful photoreduction of aryl halides under green/white light outlined the potential strength of this organic photocatalyst. Overall, a very simple synthetic approach for this acridinium family along with their versatility in photooxidation and reduction sheds a new light on the acridinium photochemistry.

<b>A new class of highly reducing acridiniums in photochemistry. </b>(<b>A</b>) Activation of C(sp<sup>2</sup>)-X bond by the acridiniums under green (λ = 518 nm) or white LED. (<b>B</b>) Photoexcited oxidative and reductive quenching cycle of the new acridinium family. A, electron acceptor; D, electron donor.

A new class of highly reducing acridiniums in photochemistry. (A) Activation of C(sp²)-X bond by the acridiniums under green (λ = 518 nm) or white LED. (B) Photoexcited oxidative and reductive quenching cycle of the new acridinium family. A, electron acceptor; D, electron donor.

Md Mubarak Hossain

Graduate Student, The University of Arizona

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