A Negatively Curved Pyrene-Fused Azaacene.

Non-planar aromatic hydrocarbons display distorted π-frameworks that give rise to unique optoelectronic properties. Among the different strategies for generating non-planar aromatic hydrocarbons, steric overcrowding has afforded numerous twisted structures displaying helical or alternate twists, whereas bent structures remain rare. Herein, we report a pyrene-fused azaacene derivative in which eight strategically positioned phenyl substituents enforce bending of the aromatic core rather than twisting, generating a negatively curved, saddle-shaped structure. Single-crystal x-ray diffraction reveals large deviations from planarity with bend angles of 41° and 34°, stabilised by intramolecular π-π stacking between facing phenyl rings.