Wave-shaped polycyclic hydrocarbons with controlled aromaticity.

Controlling the aromaticity and electronic properties of curved π-conjugated systems has been increasingly attractive for the development of novel functional materials for organic electronics. Herein, we demonstrate an efficient synthesis of two novel wave-shaped polycyclic hydrocarbons (PHs) and with 64 π-electrons. Among them, the wave-shaped π-conjugated carbon skeleton of is unambiguously revealed by single-crystal X-ray crystallography analysis. The wave-shaped geometry is induced by steric congestion in the cove and fjord regions. Remarkably, the aromaticity of these two structural isomers can be tailored by the annulated direction of cyclopenta[]fluorene units. Isomer (optg = 1.13 eV) behaves as a closed-shell compound with weakly antiaromatic feature, whereas its structural isomer displays a highly stable tetraradical character ( = 0.23; = 0.22; = 91 days) with a narrow optical energy gap of 0.96 eV. Moreover, the curved PH exhibits remarkable ambipolar charge transport in solution-processed organic thin-film transistors. Our research provides a new insight into the design and synthesis of stable functional curved aromatics with multiradical characters.