Acenaphthylene-fused cyclo[8]pyrroles with intense near-IR-region absorption bands

Tetsuo Okujima, Chie Ando, John Mack, Shigeki Mori, Ichiro Hisaki, Takahiro Nakae, Hiroko Yamada, Keishi Ohara, Nagao Kobayashi, Hidemitsu Uno

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18 Citations (Scopus)

Abstract

An acenaphthylene-fused cyclo[8]pyrrole was synthesized by using an oxidative coupling reaction of the corresponding 2,2'-bipyrrole. Two conformational isomers 1 a and 1 b were isolated, and their molecular structures were elucidated by X-ray crystallographic studies. The less-polar and lower-symmetry 1 b isomer can be converted into the 1 a isomer through a thermal ring flip. Application of the perimeter model developed by Michl to magnetic circular dichroism spectroscopic data and theoretical calculations demonstrate that there is a marked redshift of the near-IR absorption maxima relative to cyclo[8]isoindole because there is a significant stabilization of the LUMO due to the differing effects of a fused ring expansion with acenaphthylene and benzene moieties on the frontier π molecular orbitals. Fused ring expansion: An oxidative coupling reaction of the corresponding 2,2'-bipyrrole leads to the synthesis of an acenaphthylene-fused cyclo[8]pyrrole. Application of Michl's perimeter model to magnetic circular dichroism spectral data and the results of theoretical calculations demonstrate that there is a marked redshift of the near-IR absorption maxima (see figure).

Original languageEnglish
Pages (from-to)13970-13978
Number of pages9
JournalChemistry - A European Journal
Volume19
Issue number41
DOIs
Publication statusPublished - 2013 Oct 4

Keywords

  • IR spectroscopy
  • circular dichroism
  • density functional calculations
  • macrocycles
  • pyrroles

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry

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    Okujima, T., Ando, C., Mack, J., Mori, S., Hisaki, I., Nakae, T., Yamada, H., Ohara, K., Kobayashi, N., & Uno, H. (2013). Acenaphthylene-fused cyclo[8]pyrroles with intense near-IR-region absorption bands. Chemistry - A European Journal, 19(41), 13970-13978. https://doi.org/10.1002/chem.201301294