Azepine‐ or Azocine‐Embedded Hexabenzocoronene Derivatives as Nitrogen‐Doped Saddle or Saddle‐Helix Nanographenes

Abstract

AbstractTwo novel nitrogen‐doped, hexa‐peri‐hexabenzocoronene (HBC)‐based nanographenes (NGs) 1 and 2 bearing an azepine and an azocine at the fjord region, respectively, were synthesized and characterized. Notably, structure 1 was synthesized by Diels–Alder reaction of cyclic alkene and tetrachlorothiophene‐S,S‐dioxide, followed by Suzuki–Miyaura cross‐coupling and Scholl‐type reactions, which represents a modified strategy to construct NGs. The azo‐heptagon‐embedded NG 1 leads to a saddle shape, and the azo‐octagon‐embedded NG 2 exhibits a distorted saddle‐helix conformation with the largest torsion angle recorded so far in [5]helicenes. As a result, the different structural topographies for NGs 1 and 2 lead to significant changes in the optical properties including UV absorption and fluorescent emission. Additionally, the 8π‐heterocycles azepine and azocine in the NGs 1 and 2 exhibited obvious antiaromatic properties.