The Extension of Baird's Rule to Twisted Heteroannulenes: Aromaticity Reversal of Singly and Doubly Twisted Molecular Systems in the Lowest Triplet State

Yongseok Hong, Juwon Oh, Young Mo Sung, Yasuo Tanaka, Atsuhiro Osuka, Dongho Kim

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13 Citations (Scopus)


We have investigated the aromaticity of singly twisted Möbius aromatic and doubly twisted Hückel antiaromatic bis(palladium(II)) [36]octaphyrins in the lowest triplet state (T1) by spectroscopic measurements and quantum calculations. The T1 state of the singly twisted Möbius [36]octaphyrin shows broad and weak absorption spectral features that are analogous to those of antiaromatic expanded porphyrins while the T1 state of the doubly twisted Hückel [36]octaphyrin exhibits intense and distinct spectral features, indicating the aromatic nature. These results along with theoretical calculations support the hypothesis that the aromaticity is reversed in the T1 state. Furthermore, we show that the degree of structural smoothness affects the aromaticity reversal in the T1 state.

Original languageEnglish
Pages (from-to)2932-2936
Number of pages5
JournalAngewandte Chemie - International Edition
Issue number11
Publication statusPublished - 2017 Jan 1


All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)

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