Photoinduced electron transfer in triazole-bridged donor-acceptor dyads - A critical perspective

In recent years, dyads in which molecular donor and acceptor moieties are chemically linked by a bridg-ing ligand have emerged as attractive systems for light-driven catalysis. Their modular structure, control-lable donor-acceptor distance, and their ability to undergo light-driven charge transfer, which is not limited by diffusion, render such systems promising in light-driven charge-transfer reactions and light -driven redox catalysis. Copper-catalyzed alkyne azide cycloaddition (CuAAC) is a particularly popular synthetic strategy for coupling donor and acceptor moieties. This CLICK chemistry approach yields dyads with a 1,2,3-triazole bridging motif. In this review, we discuss the complex role played by this triazole linker to drive electron transfer (eT) in a respective triazole-bridged donor-acceptor dyad upon photoex-citation. We review how structural and electronic properties of the bridge influence charge separation and recombination rates. Furthermore, the role of the triazole bridge energetics in thermal as well as oxidative and reductive photoinduced eT will be discussed. Finally, criteria for the design of dyads with different eT properties are derived.(c) 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

In recent years, dyads in which molecular donor and acceptor moieties are chemically linked by a bridging ligand have shown promise in light-driven catalysis. The modular structure, control-lable donor-acceptor distance, and light-driven charge transfer abilities make these systems attractive for light-driven charge-transfer reactions and light-driven redox catalysis. This review discusses the role of 1,2,3-triazole bridging motif in driving electron transfer in triazole-bridged donor-acceptor dyads upon photoexcitation, and how the structural and electronic properties of the bridge influence charge separation and recombination rates. Criteria for designing dyads with different electron transfer properties are also derived.