Ionic viologens are external-responsive compounds that can be reduced not only by electric field application but also by UV light irradiation. If the viologens can be given the inherent properties of liquid crystals, the application field of viologen will expand. In this study, viologen compounds with asymmetric rigid moiety were synthesized by introduction of an aromatic ring on one side of 4,4’-bipyridine and their liquid-crystalline (LC) properties were investigated. Compared with the extended viologen with a symmetric rigid moiety, the viologen with asymmetric moiety exhibited a low-ordered LC phase, and the crystalline-LC phase transition temperature was lowered by more than 100 °C.
