Acenaphthylene‐Fused Cyclo[8]pyrroles with Intense Near‐IR‐Region Absorption Bands. Issue 41 (26th August 2013)

• Record Type: Journal Article
• Authors: Okujima, Tetsuo; Ando, Chie; Mack, John; Mori, Shigeki; Hisaki, Ichiro; Nakae, Takahiro; Yamada, Hiroko; Ohara, Keishi; Kobayashi, Nagao; Uno, Hidemitsu
• Is Part Of: Chemistry. Volume 19:Issue 41(2013)
• Page Start: 13970
• Page End: 13978
• Publication Date: 2013-08-26
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201301294
• Languages: English
• ISSNs: 0947-6539

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>An acenaphthylene‐fused cyclo[8]pyrrole was synthesized by using an oxidative coupling reaction of the corresponding 2, 2′‐bipyrrole. Two conformational isomers <bold>1 a</bold> and <bold>1 b</bold> were isolated, and their molecular structures were elucidated by X‐ray crystallographic studies. The less‐polar and lower‐symmetry <bold>1 b</bold> isomer can be converted into the <bold>1 a</bold> 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.</p> </abstract>