Extension of Non‐alternant Nanographenes Containing Nitrogen‐Doped Stone‐Thrower‐Wales Defects
Chang Wang, Ziqi Deng, David Lee Phillips, Junzhi Liu
Abstract
Abstract Non‐alternant topologies have attracted considerable attention due to their unique physiochemical characteristics in recent years. Here, three novel topological nanographenes molecular models of nitrogen‐doped Stone–Thrower–Wales (S–T–W) defects were achieved through intramolecular direct arylation. Their chemical structures were unambiguously elucidated by single‐crystal analysis. Among them, threefold intramolecular direct arylation compound (C 42 H 21 N) is the largest nanographene bearing a N‐doped non‐alternant topology to date, in which the non‐benzenoid rings account for 83 % of the total molecular skeleton. The absorption maxima of this compound was located in the near‐infrared region with a long tail up to 900 nm, which was much longer than those reported for similarly sized N‐doped nanographene with six‐membered rings (C 40 H 15 N). In addition, the electronic energy gaps of these series compounds clearly decreased with the introduction of non‐alternant topologies (from 2.27 eV to 1.50 eV). It is noteworthy that C 42 H 21 N possesses such a low energy gap ( E g opt =1.40 eV; E g cv =1.50 eV), yet is highly stable under ambient conditions. Our work reported herein demonstrates that the non‐alternant topology could significantly influence the electronic configurations of nanocarbons, where the introduction of a non‐alternanting topology may be an effective way to narrow the energy gap without extending the molecular π‐conjugation.