Azulene-Fused Acenes

Albert Ong, Tao Tao, Qing Jiang, Yi Han, Yaping Ou, Kuo-Wei Huang, Chunyan Chi

Research output: Contribution to journalArticlepeer-review

Abstract

Non-alternant non-benzenoid π-conjugated polycyclic hydrocarbons (PHs) are expected to exhibit very different electronic properties from the all-benzenoid PHs. Herein, we report the synthesis and physical properties of three azulene-fused acene molecules ( 1 , 2 and 3 ), which are isoelectronic to the pentacene, hexacene and heptacene, respectively. X-ray crystallographic analysis, NMR spectra, and theoretical calculations reveal a localised aromatic backbone comprising of all the six- and five-membered rings while the seven-membered ring remains non-aromatic. They display properties of both azulene and acenes and are much more stable than the respective acenes. The dications of 1 , 2 and 3 were formed by chemical oxidation. Notably, 3 2+ exhibited an open-shell diradical character (y 0 = 30.2%) as confirmed by variable-temperature NMR and ESR measurements, which can be explained by recovery of aromaticity of an 2,6-anthraquinodimethane unit annulated with two aromatic tropylium rings.
Original languageEnglish (US)
JournalAngewandte Chemie International Edition
DOIs
StatePublished - Jul 13 2022

ASJC Scopus subject areas

  • Chemistry(all)
  • Catalysis

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