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Proton-coupled electron transfer of macrocyclic ring hydrogenation: The chlorinphlorin.

ABSTRACT: SignificanceThe chemical reduction of unsaturated bonds occurs by hydrogenation with H₂ as the reductant. Conversely, in biology, the unavailability of H₂ engenders the typical reduction of unsaturated bonds with electrons and protons from different cofactors, requiring olefin hydrogenation to occur by proton-coupled electron transfer (PCET). Moreover, the redox noninnocence of tetrapyrrole macrocycles furnishes unusual PCET intermediates, including the phlorin, which is an intermediate in tetrapyrrole ring reductions. Whereas the phlorin of a porphyrin is well established, the phlorin of a chlorin is enigmatic. By controlling the PCET reactivity of a chlorin, including the use of a hangman functionality to manage the proton transfer, the formation of a chlorinphlorin by PCET is realized, and the mechanism for its formation is defined.

SUBMITTER: Sun R

PROVIDER: S-EPMC9171799 | biostudies-literature | 2022 May

REPOSITORIES: biostudies-literature

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Proton-coupled electron transfer of macrocyclic ring hydrogenation: The chlorinphlorin.

Sun Rui R Liu Mengran M Zheng Shao-Liang SL Dogutan Dilek K DK Costentin Cyrille C Nocera Daniel G DG

Proceedings of the National Academy of Sciences of the United States of America 20220509 20

SignificanceThe chemical reduction of unsaturated bonds occurs by hydrogenation with H<sub>2</sub> as the reductant. Conversely, in biology, the unavailability of H<sub>2</sub> engenders the typical reduction of unsaturated bonds with electrons and protons from different cofactors, requiring olefin hydrogenation to occur by proton-coupled electron transfer (PCET). Moreover, the redox noninnocence of tetrapyrrole macrocycles furnishes unusual PCET intermediates, including the phlorin, which is an ...[more]

PMID: 35533271

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