Hexabenzo[4.4.4]propellane: a helical molecular platform for the construction of electroactive materials.

Helical hexabenzo[4.4.4]propellane (a relative of hexaphenylethane) and its derivatives are synthesized and their structures are established by X-ray crystallography. Isolation and X-ray crystallographic characterization of a robust trication-radical salt of hexamethoxypropellane derivative confirms that its framework is stable toward oxidative (aliphatic) C-C bond cleavage. It is also demonstrated that propellane can be easily brominated at the 4,4'-positions of the biphenyl linkages for its usage as a molecular platform for the preparation of electroactive materials.