Graduate School of Science and Engineering, Ehime University, Matsuyama 790-8577 (Japan), Fax: (+81) 89-927-9615.
Chemistry. 2013 Oct 4;19(41):13970-8. doi: 10.1002/chem.201301294. Epub 2013 Aug 26.
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.
通过相应的 2,2'-联吡啶的氧化偶联反应合成了一个苊并[8]环吡咯。分离得到了两种构象异构体 1a 和 1b，并通过 X 射线晶体学研究阐明了它们的分子结构。非极性和低对称性的 1b 异构体可以通过热环翻转转化为 1a 异构体。Michl 开发的周长模型在应用于磁圆二色光谱数据和理论计算时表明，与环[8]异吲哚相比，近红外吸收最大值有明显的红移，因为由于苊并和苯部分的融合环扩展对前线π分子轨道的不同影响，LUMO 得到了显著的稳定。
