Satellite-Dish-Shaped Pentagon- and Heptagon-Embedded Nanographene Build on a Central Pyrrolo[3,2-b]pyrrole Core.

A bowl-shaped nitrogen-doped nanographene composed of a pyrrolo[3,2- b ]pyrrole core substituted with six arene rings circularly bonded with one another, has been prepared via a concise synthetic strategy encompassing the multicomponent tetraarylpyrrolopyrrole (TAPP) synthesis, the Scholl reaction and intramolecular direct arylation. This synthesis represents the first case of programmed sequential intramolecular direct arylation reactions utilizing the different reactivity of C-Br and C-Cl bonds. The target non-alternant, nitrogen-embedded polycyclic aromatic hydrocarbon (PAH) contains two central pentagons confined between two adjacent heptagons - the inverse Stone-Thrower-Wales topology. The presence of both five- and seven-membered rings in the final structure, entailing concurrent positive and negative Gaussian curvature within its surface (bowl depth ≈2 Å), is responsible for interesting properties such as a perpendicularly aligned dipole moment, absorption and fluorescence in the orange-red region, weak emission originating from the charge-transfer character of a low-energy absorption band, and a high lying HOMO. In the solid state slipped convex-to-convex π-π stacking prevails rather than convex-to-concave.