Triperyleno[3,3,3]propellane triimides: Achieving a new generation of quasi-: D _3h symmetric nanostructures in organic electronics

Rigid three-dimensional (3D) polycyclic aromatic hydrocarbons (PAHs), in particular 3D nanographenes, have garnered interest due to their potential use in semiconductor applications and as models to study through-bond and through-space electronic interactions. Herein we report the development of a novel 3D-symmetric rylene imide building block, triperyleno[3,3,3]propellane triimides (6), that possesses three perylene monoimide subunits fused on a propellane. This building block shows several promising characteristics, including high solubility, large π-surfaces, electron-accepting capabilities, and a variety of reactive sites. Further, the building block is compatible with different reactions to readily yield quasi-D_3h symmetric nanostructures (9, 11, and 13) of varied chemistries. For the 3D nanostructures we observed red-shift absorption maxima and amplification of the absorption coefficients when compared to the individual subunits, indicating intramolecular electronic coupling among the subunits. In addition, the microplates of 9 exhibit comparable mobilities in different directions in the range of 10^-3 cm² V^-1 s^-1, despite the rather limited intermolecular overlap of the π-conjugated moieties. These findings demonstrate that these quasi-D_3h symmetric rylene imides have potential as 3D nanostructures for a range of materials applications, including in organic electronic devices.