A long-standing goal in understanding bioenergetic processes is the ability to couple proton transport with redox processes in order to set up the energy gradients required to drive new chemical reactions. Proton-coupled electron transfer (PCET) is the essential process that links the electron and proton transfer reactions, and understanding the factors that govern PCET yields new tools and insights to design materials for electron and proton transport. In artificial photosynthetic constructs, proton translocation of four protons along a ~ 16 Angstrom proton relay has been observed as the result of oxidation of a phenol-based model of Tyrz in photosynthesis. The length of the proton relay, as well as the number of protons involved, may be modified by incorporating additional benzimidazole moieties along the network. In this reversible process, reversing the electrode potential to reducing conditions changes the direction of the proton translocation, recovering the initial neutral species. Theoretical studies highlight key energetic and structural factors involved in the process, paving the way toward designing new proton relays based on tuning the pKa’s of intermediates along the proton relay. Such insights are valuable to understanding bioenergetics as well as developing new artificial photosynthetic systems.

Engineering a redox-active proton wire with proton-coupled electron transfer

2019 Fall National Meeting

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