Issue 14, 2021

Redox-induced reversible [2 + 2] cycloaddition of an etheno-fused diporphyrin


3,5-Ethenoporphyrin is a π-extended porphyrin containing a fused ethene unit between the meso- and β-positions, exhibiting unique contribution of macrocyclic antiaromaticity. We have recently reported that its analogue, etheno-fused diporphyrin, underwent thermal [2 + 2] cycloaddition to furnish X-shaped cyclobutane-linked tetraporphyrins. Here we demonstrate that the cyclobutane-ring formation is dynamically redox-active. Namely, the tetraporphyrin underwent two-step four-electron oxidation to afford two etheno-fused diporphyrin dications. The reduction of the resulting dication regenerated the cyclobutane-linked tetraporphyrin. The dication was sufficiently stable to allow its isolation under ambient conditions. The structure of the dication has been confirmed by 1H NMR spectroscopy and X-ray diffraction analysis. Importantly, the simultaneous double C–C bond cleavage in the cyclopropane ring in the tetraporphyrin is exceptional among dynamic redox (dyrex) systems to achieve large structural changes, thus offering new insights for the design of novel redox-active functional organic materials for electrochromic dyes, organic batteries, and organic memories.

Graphical abstract: Redox-induced reversible [2 + 2] cycloaddition of an etheno-fused diporphyrin

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Article information

Article type
Edge Article
24 Jan 2021
23 Feb 2021
First published
24 Feb 2021
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2021,12, 5224-5229

Redox-induced reversible [2 + 2] cycloaddition of an etheno-fused diporphyrin

K. Miyagawa, I. Hisaki, N. Fukui and H. Shinokubo, Chem. Sci., 2021, 12, 5224 DOI: 10.1039/D1SC00438G

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