Mechanochromism, Twisted/Folded Structure Determination, and Derivatization of (N-Phenylfluorenylidene)acridane

Yutaka Matsuo, Ya Wang, Hiroshi Ueno, Takafumi Nakagawa, Hiroshi Okada

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48 Citations (Scopus)


(N-Phenylfluorenylidene)acridane (Ph-FA) compounds with electron-withdrawing and -donating substituents (H, MeO, Ph, NO2, Br, F) at the para position of the phenyl group were successfully synthesized by Barton–Kellogg reactions of N-aryl thioacridones and diazofluorene. By using the substituent on the nitrogen atom to alter the electronic properties, both the folded and twisted conformers of p-NO2-C6H4-FA could be crystallographically characterized, which enabled the charge transfer from the electron-donating acridane moiety to the electron-accepting fluorenylidene moiety to be understood. Ground-state mechanochromism, thermochromism, vapochromism, and proton-induced chromism were demonstrated between the folded and twisted conformations of the conformers. Protonation and chemical oxidation of Ph-FA gave two stable acridinium compounds, namely, the fluorenylacridinium and acridinium radical cations. The present study will contribute to the development of functional dyes and organic semiconductors.

Original languageEnglish
Pages (from-to)8762-8767
Number of pages6
JournalAngewandte Chemie - International Edition
Issue number26
Publication statusPublished - 2019 Jun 24


  • aromatic enes
  • conformers
  • mechanochromism
  • nitrogen heterocycles
  • overcrowded alkenes


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