Synthesis of a Sidewall Fragment of a (12,0) Carbon Nanotube

Synthesis of a carbon nanobelt (CNB) is a very challenging task in organic chemistry. Herein, we report the successful synthesis of an octabenzo[12]cyclacene based CNB ( 6 ), which can be regarded as a sidewall fragment of a (12,0) carbon nanotube. The key intermediate compound, a tetraepoxy nanobelt ( 5 ), was first synthesized by Diels–Alder reaction, and subsequent reductive aromatization gave the fully conjugated CNB 6 . X‐ray crystallographic analysis unambiguously confirmed the belt‐shaped structure of 6 . 1 H NMR spectrum and theoretical calculations (ACID, NICS, and 2D/3D ICSS) revealed localized aromaticity and stronger shielding chemical environment in the inner region of the belt. The optical properties (absorption and emission) of 6 were studied and correlated to its electronic structure. Strain analysis indicates that the phenyl substituents at the zigzag edges are crucial to the successful synthesis of 6 . This report presents a new strategy towards highly strained CNBs.