Zethrene and dibenzozethrene: Masked biradical molecules

Ya Chu Hsieh, Hau Yu Fang, Yi Ting Chen, Rong Yang, Chen I. Yang, Pi Tai Chou, Ming Yu Kuo, Yao Ting Wu

Research output: Contribution to journalArticlepeer-review

21 Citations (Scopus)


The syntheses, structures, and physical properties of dibenzozethrenes were explored. The results thus obtained were compared with those for zethrenes. Dibenzozethrenes were synthesized by the nickel-catalyzed cyclodimerization of 9-ethynyl-1-iodoanthracenes. The substituents in zethrene and dibenzozethrene twisted their backbones, and remarkably influenced their properties. Unlike closed-shell disubstituted derivatives, the parent zethrene and dibenzozethrene are singlet open-shell biradicals, which were studied by variable-temperature 1H NMR, ESR, SQUID and computational methods. Since substituents were observed to affect significantly the biradical properties, the relevant mechanisms were analyzed. The nonlinear optical performance of each of these compounds depends on its π-conjugation and biradical properties. Dibenzozethrenes have larger two-photon absorption cross-sections than zethrenes, as most strongly evidenced by the parent dibenzothrene [σmax = 4323 GM at 530 nm].

Original languageEnglish
Pages (from-to)3069-3073
Number of pages5
JournalAngewandte Chemie - International Edition
Issue number10
Publication statusPublished - 2015 Mar 2

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)


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