Synthesis of a Dicycloheptaheptalene‐Containing Polycyclic Conjugated Hydrocarbon and the Impact of Non‐Alternant Topologies

Incorporating non‐hexagonal rings into polycyclic conjugated hydrocarbons (PCHs) can significantly affect their electronic and optoelectronic properties and chemical reactivities. Here, we report the first bottom‐up synthesis of a dicyclohepta[a,g]heptalene‐embedded PCH (1) with four continuous heptagons, which are arranged in a “Z” shape. Compared with its structural isomer bischrysene 1 R with only hexagonal rings, compound 1 presents a distinct antiaromatic character, especially the inner heptalene core, which possesses clear antiaromatic nature. In addition, PCH 1 exhibits a narrower highest occupied molecular orbital (HOMO)‐lowest unoccupied molecular orbital (LUMO) energy gap than its benzenoid contrast 1 R, as verified by experimental measurements and theoretical calculations. Our work reported herein not only provides a new way to synthesize novel PCHs with non‐alternant topologies but also offers the possibility to tune their electronic and optical properties.