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

Abstract A liquid crystalline perylene bisimide bearing a 12-crown-4 ring was synthesized. This perylene bisimide derivative exhibited an oblique columnar phase at room temperature and formed a 1:1 complex with lithium triflate, but not with sodium triflate. An atomic force microscopic study on the surface morphologies of the spin-coated films of the liquid crystalline (LC) perylene bisimide indicated a characteristic straight-stripe pattern over several hundred nanometers. An atomic force micrographic study also revealed that a 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 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 the crown rings interacted with triflate anions to stabilize the fibrous nanoaggregates of the perylene bisimide moieties.