N-doped Nonalternant Aromatic Belt via a Six-fold Annulative Double N-Arylation

Nitrogen (N)-doped nanocarbon materials have received significant attention in materials science. Therefore, the design and synthesis of new molecular scaffolds are of great importance. Herein, we report the synthesis and X-ray crystal structure of a nitrogen-inserted nonalternant aromatic belt. The palladium-catalyzed six-fold annulative double N-arylation provided an aromatic belt bearing six nitrogen atoms in one step from cyclo[6]paraphenylene-Z-ethenylene, the precursor of the (6,6)carbon nanobelt. The C3i-symmetric structure of the aromatic belt in the solid state was revealed using X-ray crystallography. The multistep chemical oxidation behavior of the belt, which was facilitated by the six p-methoxyaniline moieties, was studied, and a stable dication species was successfully isolated and identified by X-ray crystallography. The present study not only shows the unique structure and properties of the N-doped nonalternant aromatic belt but also expands the scope of accessibility of synthetically difficult belt molecules by the conventional intramolecular contraction pathway.