Diarylethene
From Wikipedia, the free encyclopedia
In chemistry, diarylethene is the general name of a class of compounds that have aromatic groups bonded to each end of a carbon-carbon double bond.
These compounds can exist in two isomeric forms:
- The "open-ring" form
- The "closed-ring" form, in which an additional bond joins the two aromatic rings to each other
An interesting characteristic of diarylethenes is their reversible interconversion between these two forms. The open-ring isomers transform into the closed-ring isomers via a photocyclization reaction induced by irradiation with ultraviolet light, and the closed-ring isomers are converted to the open-ring isomers via a photoreversion reaction induced by irradiation with visible light.
[edit] Applications
Typically, the open-ring isomers are colorless compounds, whereas the closed-ring isomers have colors dependent on 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.
