Efficient Synthesis of a Novel, Twisted and Stable, Electroluminescent “Twistacene”

A twistacene, 6,8,15,17-tetraphenyl-1.18,4.5,9.10,13.14-tetrabenzoheptacene (3), was synthesized using a mild and novel bisbenzyne precursor.
It was characterized by X-ray crystallography, NMR, UV−vis, and IR spectroscopies, as well as cyclic voltammetry and DFT calculations. The
heptacene derivative possesses a nonpropeller twist topology and is unusually stable for a highly conjugated oligoacene. In addition, it is
fluorescent, with a quantum efficiency of 15%. Distortion from planarity, mostly due to the phenyl substituents, causes only marginal changes
in electronic properties and is beneficial for redox reversibility, which is required for efficient OLED devices.