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

Abstract

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. 1H 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.

A Green Fluorescent Nitrogen‐Doped Aromatic Belt Containing a [6]Cycloparaphenylene Skeleton

“…In summary, we have provided a highly efficient approach to the convenient synthesis of a nitrogen-doped aromatic belt with [6]cycloparaphenylene skeleton starting from an easily avaliable calix [3]carbazole. The NDAB showed a conjugated belt-shaped structure and deep cavity, and it could encapsulate one CH 2 Cl 2 molecule in both solution and solid state.…”

“…Abstract: The design and synthesis of nitrogen-doped aromatic belts with conjugated structures still remain a challenge. Here, we report the first nitrogen-doped aromatic belt with a [6]cycloparaphenylene skeleton, which is conveniently synthesized from the easily available calix [3]carbazole. The aromatic belt has a rigid conjugated structure and deep cavity, and it can encapsulate one dichloromethane both in solution and in the solid state.…”

“…Inspired by our recent report on the highly efficient synthesis of C(sp 3 )-bridged [6]CPPs from fluoren [3]arenes, [16] we herein report the first nitrogen-doped aromatic belt (NDAB) containing [6]CPP skeleton, which can be synthesized highly efficiently by the formation of three-fold aryl C À C bonds from an easily available calix [3]carbazole (Figure 1 b). The NDAB shows a belt-shaped conjugated structure and deep cavity, and it can encapsulate one dichloromethane in both solution and solid state.…”

“…Synthesis of the NDAB is depicted in Scheme 1. According to the similar method reported by Yang, [17] we first prepared calix [3]carbazole 3 in 73 % yield by the FeCl 3 •6 H 2 O catalyzed one-pot condensation between 2,7-dimethoxy-9phenylcarbazole 1 and paraformaldehyde in dichloromethane at 0 8C. For a comparison, macrocycle 4 was also synthesized starting from compound 2.…”

“…[1] Although the construction of such kinds of conjugated belts underwent more than 60 years of efforts, a breakthrough was made with the synthesis of the first armchair carbon nanobelt in 2017. [2] Recently, Chi, [3] Itami, [4] and Miaos group [5] reported the successful synthesis of zig-zag conjugated nanobelts. [6] Meanwhile, along with the investigation of all-carbon conjugated nanobelts, some efforts focused on the incorporation of heteroatoms into the aforementioned belts were also explored to fulfill the construction of new class of CNTs with heterojunctions.…”