Nanostructures of liquid crystalline thin films of perylene bisimide derivatives bearing a 12-crown-4 ring complexing with lithium triflate

A liquid crystalline perylene bisimide bearing a 12-crown-4 ring was synthesized. This perylene bisimide derivative exhibited the oblique columnar phase at room temperature and formed a 1:1 complex with lithium triflate but not with sodium triflate. The atomic force microscopic study on the surface morphologies of the spin-coated films of the LC perylene bisimide indicated a characteristic straight stripe pattern over several hundred nm. The atomic force micrographic study also revealed that the well-defined bent stripe pattern with a periodicity of 7 nm was formed on the thin film of the complex with lithium triflate while a well-defined stripe structure was not observed on the film of the mixture with sodium triflate. The well-defined nanostructures in the surface morphologies of the thin films of the 1:1 complex with lithium triflate were retained during the in situ polymerization, while the nanostructure was completely disordered in the thin film of the pure LC perylene bisimide during the polymerization. Alkaline metal cations binding to crown rings interacted with triflate anions to stabilize the fibrous nanoaggregates of perylene bisimide moieties.