Division of Frontier Materials Science, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan.
Chem Soc Rev. 2015 Sep 21;44(18):6560-77. doi: 10.1039/c5cs00185d. Epub 2015 Apr 30.
"Kekulene" is a doughnut-like shaped polycyclic aromatic hydrocarbon consisting of cyclically arrayed benzene rings. It has attracted a great deal of theoretical interest because it is regarded as an ideal model to study conjugation circuits of π electrons, i.e. whether they delocalize locally in benzene rings or globally throughout the molecule. Though kekulene was synthesized in 1978, it was the only known compound of this class of compounds for a long time. Recently, new kekulene-related molecules, septulene, which is a non-alternant benzenoid hydrocarbon, and a tetracyclopentatetraphenylene (TCPTP) derivative belonging to non-alternant non-benzenoid hydrocarbons, were synthesized. This article presents theoretical and experimental aspects of kekulene-related molecules focusing on the viewpoint of conjugation circuits by classifying them into three types: benzenoid kekulenes including kekulene itself and septulene, yet unknown anti-kekulene and non-alternant non-benzenoid kekulenes represented by TCPTP.
“Kekulene”是一种类似甜甜圈形状的多环芳烃，由周期性排列的苯环组成。它引起了极大的理论兴趣，因为它被认为是研究π电子共轭电路的理想模型，即它们是局部定域在苯环上还是全局定域在整个分子中。尽管 Kekulene 于 1978 年被合成，但在很长一段时间内它是唯一已知的此类化合物。最近，新的 Kekulene 相关分子，即 septulene，一种非交替苯并型碳氢化合物，以及属于非交替非苯并型碳氢化合物的四环戊四苯并菲（TCPTP）衍生物被合成。本文介绍了 Kekulene 相关分子的理论和实验方面，重点从共轭电路的角度将它们分为三类：苯并型 Kekulene，包括 Kekulene 本身和 septulene；以及未知的反-Kekulene 和由 TCPTP 代表的非交替非苯并型 Kekulene。
