A compound that is fluidized by light irradiation and reversibly non-fluidized and is represented by the following general formula (1): ##STR00001## In the general formula (1), Ar.sub.1 and Ar.sub.2 each independently represent an aromatic hydrocarbon group optionally having a substituent or an aromatic heterocyclic group optionally having a substituent, and Y, Z.sub.1, and Z.sub.2 each independently represent a hydrogen atom or a lower alkyl group.