A New Class of N-doped Ionic PAHs Via Intramolecular [4+2]-cycloaddition Between Arylpyridines and Alkynes

Reported herein, for the first time, is a copper-promoted intramolecular [4+2]-cycloaddition cascade to access ionic N-doped polycyclic aromatic hydrocarbons (PAHs) with tunable emission wavelengths. It is shown that the reaction can be made catalytic with respect to Cu(OTf)2 when an external oxidant, Selectfluor, was used.