Proton-Coupled Redox Switching in an Annulated π-Extended Core-Modified Octaphyrin

Tridib Sarma, Gakhyun Kim, Sajal Sen, Won Young Cha, Zhiming Duan, Matthew D. Moore, Vincent M. Lynch, Zhan Zhang, Dongho Kim, Jonathan L. Sessler

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16 Citations (Scopus)

Abstract

Proton-coupled electron transfer (PCET) is an important chemical and biological phenomenon. It is attractive as an on-off switching mechanism for redox-active synthetic systems but has not been extensively exploited for this purpose. Here we report a core-modified planar weakly antiaromatic/nonaromatic octaphyrin, namely, a [32]octaphyrin(1.0.1.0.1.0.1.0) (1) derived from rigid naphthobipyrrole and dithienothiophene (DTT) precursors, that undergoes proton-coupled two-electron reduction to produce its aromatic congener in the presence of HCl and other hydrogen halides. Evidence for the production of a [4n + 1] π-electron intermediate radical state is seen in the presence of trifluoroacetic acid. Electrochemical analyses provide support for the notion that protonation causes a dramatic anodic shift in the reduction potentials of octaphyrin 1, thereby facilitating electron transfer from halide anions (viz. I-, Br-, and, Cl-). Electron-rich molecules, such as tetrathiafulvene (TTF), phenothiazine (PTZ), and catechol, were also found to induce PCET in the case of 1. Both the oxidized and two-electron reduced forms of 1 were characterized by X-ray diffraction analyses in the solid state and in solution via spectroscopic means.

Original languageEnglish
Pages (from-to)12111-12119
Number of pages9
JournalJournal of the American Chemical Society
Volume140
Issue number38
DOIs
Publication statusPublished - 2018 Sep 26

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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    Sarma, T., Kim, G., Sen, S., Cha, W. Y., Duan, Z., Moore, M. D., Lynch, V. M., Zhang, Z., Kim, D., & Sessler, J. L. (2018). Proton-Coupled Redox Switching in an Annulated π-Extended Core-Modified Octaphyrin. Journal of the American Chemical Society, 140(38), 12111-12119. https://doi.org/10.1021/jacs.8b06938