In chemistry, diarylethene is the general name of compounds that have two aromatic groups on both sides of a carbon-carbon double bond.

There are two isomers of diarylethenes: the open-ring form and the closed-ring form. The most interesting characteristic of diarylethenes is their reversible interconversion. The open-ring isomers transform into the closed-ring isomers via a photocyclization reaction caused by ultraviolet irradiation, and the closed-ring isomers are converted to the open-ring isomers via a photoreversion reaction caused by visible light irradiation.

Applications

Typically, the open-ring isomers are colorless compounds, whereas the closed-ring isomers have colors dependent of their chemical structure. Therefore many diarylethenes have photochromic behavior both in solution and in solid state. Moreover, these two isomers differ from one another not only in their absorption spectra but also in various physical and chemical properties, such as their refractive indices, dielectric constants, and oxidation-reduction potentials. These properties can be readily controlled by reversible isomerization between the open- and closed-ring states using photoirradiation.

Among the numerous diarylethene derivatives synthesized to date, dithienylethenes, which have two thiophene rings, are the most promising candidates because of their fatigue resistance and thermally irreversible characteristics. These characteristics of diarylethenes are likely to be applied to various electronic materials such as optical memories, photoswitching, displays, and so on.