Toward Tetraradicaloid: The Effect of Fusion Mode on Radical Character and Chemical Reactivity

Pan Hu, Sangsu Lee, Tun Seng Herng, Naoki Aratani, Théo P. Gonçalves, Qingbiao Qi, Xueliang Shi, Hiroko Yamada, Kuo Wei Huang, Jun Ding, Dongho Kim, Jishan Wu

Research output: Contribution to journalArticlepeer-review

95 Citations (Scopus)


Open-shell singlet diradicaloids display unique electronic, nonlinear optical, and magnetic activity and could become novel molecular materials for organic electronics, photonics, and spintronics. However, design and synthesis of diradicaloids with a significant polyradical character is a challenging task for chemists. In this Article, we report our efforts toward a tetraradicaloid system. A series of potential tetraradicaloids by fusion of two p-quinodimethane (p-QDM) units with naphthalene or benzene rings in different modes were synthesized. Their model compounds containing one p-QDM moiety were also prepared and compared. Their ground-state structures, physical properties, and chemical reactivity were systematically investigated by various experimental methods such as steady-state and transient absorption, two-photon absorption, X-ray crystallographic analysis, electron spin resonance, superconducting quantum interference device, and electrochemistry, assisted by density functional theory calculations. It was found that their diradical and tetraradical characters show a clear dependence on the fusion mode. Upon the introduction of more five-membered rings, the diradical characters greatly decrease. This difference can be explained by the pro-aromaticity/antiaromaticity of the molecules as well as the intramolecular charge transfer. Our comprehensive studies provide a guideline for the design and synthesis of stable open-shell singlet polycyclic hydrocarbons with significant polyradical characters.

Original languageEnglish
Pages (from-to)1065-1077
Number of pages13
JournalJournal of the American Chemical Society
Issue number3
Publication statusPublished - 2016 Jan 27

Bibliographical note

Publisher Copyright:
© 2015 American Chemical Society.

All Science Journal Classification (ASJC) codes

  • Catalysis
  • General Chemistry
  • Biochemistry
  • Colloid and Surface Chemistry


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