The role of seven-membered ring in the photoisomerization and photodissociation of small aromatic molecules

Chien-Ming Tseng, Yuri A. Dyakov, Cheng Liang Huang, Yuan T. Lee, Sheng Hsien Lin, Chi Kung Ni*

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

3 Scopus citations

Abstract

Photoisomerization and photodissociation of toluene, xylene, 4-methyl-pyridine, and aniline under collision-free conditions are reviewed. For many years, it was thought that all the isomerization of aromatic molecules could be described in terms of ring permutation. One important characteristic of ring permutation is that the atoms belonging to the alkyl or amino groups attached to the aromatic ring are not involved in the exchange with the atoms within the aromatic ring. Only the relative positions of these alkyl or amino groups are changed. However, the observation of new dissociation products from toluene, xylene, 4-methyl-pyridine, and aniline suggests that a small fraction of these molecules undergo another kind of isomerization prior to dissociation. This isomerization involves the exchange between six-membered ring and seven-membered ring structures. It provides a new pathway for aromatic molecules to undergo totally different structural change. The significance of this isomerization is that the carbon atoms (or nitrogen atom) and hydrogen atoms belonging to the alkyl group (or amino group) attached to the aromatic ring are involved in an exchange with those atoms in the aromatic ring during the isomerization. The structural change and competition between isomerization and bond dissociation are discussed.

Original languageEnglish
Pages (from-to)33-40
Number of pages8
JournalJournal of the Chinese Chemical Society
Volume53
Issue number1
DOIs
StatePublished - 1 Jan 2006

Keywords

  • Aniline
  • Aromatic molecule
  • Methyl-pyridine
  • Photodissociation
  • Photoisomerization
  • Seven-membered ring
  • Toluene
  • Xylene

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