Triangle-shaped polycyclic aromatics based on tribenzocoronene: facile synthesis and physical properties

A series of triangle-shaped polycyclic aromatics have been developed according to a facile synthetic protocol with high yields. As revealed by X-ray single crystal data, their molecular conformation and packing arrangement are significantly influenced by the electronic properties and steric bulk of peripheral subunits. The ‘saddle’-shaped hexahalotribenzocoronenes (ClTBC and FTBC) possess C2 symmetric structures and can self-assemble into well-defined columnar structures, dramatically different from hexabutyoxytribenzocoronene (TBC), which adopts a C3 symmetric ‘double-concave’ structure and less efficient packing arrangement. In the compound trithiophenocoronene (TTC), the five-membered corner rings produce a more open bay-region periphery alleviating intramolecular steric congestion. As a result, the molecule adopts an almost planar conformation.