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200576 https://hdl.handle.net/2286/R.2.N.200576 http://rightsstatements.org/vocab/InC/1.0/ http://creativecommons.org/licenses/by-nc-sa/4.0 2025-05 43 pages Murray, Catherine (Caitlyn) Moore, Ana Gonzalez Lopez, Edwin Moore, Thomas Moore, Gary Barrett, The Honors College School of Molecular Sciences Proton-coupled electron transfer (PCET) in photosystem II is responsible for the water splitting and the proton gradient used to generate ATP, which sustains all life on earth. In this study, the P680-Tyr-His pair in photosystem II has been replicated by a porphyrin-BIP (benzimidazole-phenol) system capable of undergoing PCET. When the BIP is oxidized either electrochemically or photochemically, an electron is transferred from the phenol group to the electrode or the excited porphyrin. This is coupled with the transfer of the phenol proton to the hydrogen-bonded nitrogen on the benzimidazole. In this study, the properties of PCET were investigated, taking into consideration two factors: the distance the electron travels, done by introducing phenyl spacers in between the BIP and the porphyrin, and the angle of the BIP with respect to the porphyrin, introduced by the addition of fluorine atoms on the ortho-position of a phenyl spacer. Three new molecules were designed and synthesized to study these two factors in systems capable of performing a PCET process. It was shown that all molecules successfully undergo the PCET process upon electrochemical oxidation of the phenol. In the photochemical process where the excited state of the porphyrin oxidizes the phenol, the quenched fluorescence lifetime indicates that, most likely, the PCET process is taking place in these constructs. Transient absorption measurement in the visible spectra identified signals corresponding to the formation of the porphyrin radical anion. These measurements detected the electron transfer associated with PCET but did not address the proton transfer component of the process. Artificial Photosynthesis Proton-coupled electron transfer Porphyrin-BIP Modulating Distance and Conformation in Artificial Photosynthetic Constructs