Helical supramolecular aggregates, mesoscopic organisation and nanofibers of a perylenebisimide-chiral surfactant complex via ionic self-assembly

A chiral supramolecular liquid-crystalline material was produced by the complexation of a cationic perylene bisimide dye (PTCDI) with an anionic chiral phosphate surfactant (BDP) via ionic self-assembly. The aggregation behaviour of the PTCDI-BDP complex was investigated in detail in solution and in the bulk state. The UV-Vis and CD results show that helical supramolecular aggregates of the complex were formed with the enhancement of π-π stacking between perylene molecules in solution (due to low solubility in poor solvents) as well as in the bulk. Thin films of the complex exhibit fan-shaped textures in polarized optical microscopy (POM) investigations, which corresponds to a columnar mesophase. X-ray diffraction analyses confirmed this phase identification. Moreover, the complex formed a nanofibrillar structure, as imaged by TEM, when cast from dilute ethanol solutions.