Nanographene with Multiple Embedded Heptagons: Cascade Radical Photocyclization

作者：Zhen‐Lin Qiu, Xuan‐Wen Chen, Yudong Huang, Rong‐Jing Wei, Ke‐Shan Chu, Xin‐Jing Zhao, Yuan‐Zhi Tan · 发表于：Angewandte Chemie International Edition · 年份：2022 · DOI：10.1002/anie.202116955 · 被引用次数：48 · 研究领域：Synthesis and Properties of Aromatic Compounds、Graphene research and applications、Fullerene Chemistry and Applications

Although heptagons are widely found in graphenic materials, the precise synthesis of nanocarbons containing heptagons remains a challenge, especially for the nanocarbons containing multiple-heptagons. Herein, we show that photo-induced radical cyclization (PIRC) can be used to synthesize multi-heptagon-embedded nanocarbons. Notably, a nanographene containing six heptagons (1) was obtained via a six-fold cascade PIRC reaction. The structure of 1 was clearly validated and showed a Monkey-saddle-shaped conformation. Experimental bond analysis and theoretical calculations indicated that the heptagons in 1 were non-aromatic, whereas the peripheral rings were highly aromatic. Compared to planar nanographene with the same number of π electrons, 1 had a similar optical gap due to a compromise between the decreased conjugation in the wrapped structure and enhanced electronic delocalization at the rim. Electrochemical studies showed that 1 had low-lying oxidation potentials, which was attributed to the nitrogen-doping.