Nanographenes (NGs) have gained increasing attention due to their immense potential as tailor-made organic materials for nanoelectronics and spintronics. They exhibit a rich spectrum of physicochemical properties that can be tuned by controlling the size, the edge structure or by introducing structural defects in the honeycomb lattice. Here, we report the design and on-surface synthesis of NGs containing several odd-membered polycycles induced by a thermal procedure on Au(111). Our scanning tunneling microscopy, non-contact atomic force microscopy and scanning tunneling spectroscopy measurements, complemented by computational investigations, describe the formation of two non-benzenoid NGs (2A and 2B) containing four embedded azulene units in the polycyclic framework, via on-surface oxidative ring-closure reactions. Interestingly, we observe surface-catalyzed skeletal ring rearrangement reactions in the NGs, which lead to the formation of additional hep-tagonal rings as well as pentalene and as-indacene units in 2A and 2B, respectively. Both 2A and 2B on Au(111) exhibit narrow experimental frontier electronic gaps of 0.96 and 0.85 eV, respectively, and Fermi level pinning of their HOMO to-gether with considerable electron transfer to the substrate. Ab initio calculations estimate moderate open-shell biradical characters for the NGs in gas phase.

中文翻译：

---

通过氧化闭环和重排反应在表面合成非苯类纳米石墨烯

纳米石墨烯（NGs）因其作为纳米电子学和自旋电子学的定制有机材料的巨大潜力而​​受到越来越多的关注。它们表现出丰富的理化特性，可以通过控制尺寸、边缘结构或在蜂窝晶格中引入结构缺陷来调整。在这里，我们报告了包含由 Au(111) 上的热程序诱导的几个奇数多环的 NGs 的设计和表面合成。我们的扫描隧道显微镜、非接触式原子力显微镜和扫描隧道光谱测量，辅以计算研究，描述了通过表面在多环框架中包含四个嵌入的 azulene 单元的两种非苯类 NG（2A 和 2B）的形成氧化闭环反应。有趣的是，我们观察到 NGs 中表面催化的骨架环重排反应，这导致在 2A 和 2B 中分别形成额外的七角环以及戊烯和茚并单元。Au(111) 上的 2A 和 2B 分别表现出 0.96 和 0.85 eV 的窄实验前沿电子间隙，以及它们的 HOMO 的费米能​​级钉扎在一起，并有相当多的电子转移到基板上。从头算计算估计了气相中 NG 的中等开壳双自由基特征。和费米能级将他们的 HOMO 固定在一起，并有相当多的电子转移到基板上。从头算计算估计了气相中 NG 的中等开壳双自由基特征。和费米能级将他们的 HOMO 固定在一起，并有相当多的电子转移到基板上。从头算计算估计了气相中 NG 的中等开壳双自由基特征。