Preparation and Structural Properties of Highly Twisted Polycyclic Aromatic Hydrocarbons with [4]Helicene Components

Novel di-tert-butylated polycyclic aromatic hydrocarbons (PAHs) with [4] helicene components were prepared through an oxidative photocyclisation reaction. The structural properties of the PAHs were evaluated with 1 H NMR and X-ray crystallography. It was detected that the PAHs have highly twisted π-conjugated systems and a deep fjord region. Although they are not planar, these PAHs can readily form dimers in solutions and undergo staggered one-dimensional array columnar crystal packing by intermolecular π–π interactions.