Liquid-crystalline perylene bisimide derivatives bearing an azacrown ether ring complexing with alkaline metal ions

Abstract

For electrochemical applications, solution-processable redox-active materials with ion conductivity are required. Moreover, the thin films should be insolubilized for the usage with electrolyte solutions. We synthesized a perylene bisimide derivative bearing an azacrown ether moiety. The perylene bisimide derivative exhibited a rectangular ordered columnar phase at room temperature. This compound formed liquid crystalline complexes with lithium triflate and sodium triflate in a molar ratio of 1 : 1 while phase separation occurred in the mixture with potassium triflate in a molar ratio of 1 : 1. This liquid crystalline perylene bisimide derivative was soluble even in non-polar organic solvents, due to bulky cyclotetrasiloxane rings and thin films being produced by the spin-coating method. AFM studies revealed fibrous nanostructures on the surfaces of the films of the complexes, indicating the formation of supramolecular columnar structures. The spin-coated thin film of this compound could be insolubilized by an exposure on the vapors of trifluoromethanesulfonic acid via an in situ ring-opening polymerization process. The insolubilized thin film exhibited electrochromism between red neutral and violet dianion states.