Macrocyclic furans are predicted to switch between global aromaticity and antiaromaticity, depending on their oxidation states. However, the macrocyclic furans reported to date are stabilized by electron withdrawing groups, which result in inaccessible oxidation states. To circumvent this problem, a post-macrocyclization approach was applied to introduce methylene-substituted macrocyclic furans, which display an extremely low oxidation potential of −0.23 vs. Fc/Fc+, and are partially oxidized in ambient conditions. Additional oxidation to the dication results in aromaticity switching to a global 30πe− aromatic state, as indicated by the formation of a strong diatropic current observed in the 1H NMR spectrum. NICS and ACID calculations support this trend and provide evidence for a different pathway for the global current in the neutral and dicationic states. According to these findings, macrocyclic furans can be rendered as promising p-type materials with stable oxidation states.
Bibliographical noteFunding Information:
This research was supported by the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (Grant Agreement No. 850836, ERC Starting Grant “PolyHelix”). This research was supported by The Israel Science Foundation – FIRST Program (grant No. 1453/19).
© 2022 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.
- macrocyclic compounds
- organic semiconductors
- π-conjugated macrocycles