Diarylethene

Diarylethene is a class of organic compounds that exhibit photochromism, meaning they can change color upon exposure to light of specific wavelengths. This property arises from their ability to undergo reversible photochemical ring-closing and ring-opening reactions. In their open-ring form, diarylethenes typically absorb light in the ultraviolet (UV) region. Upon irradiation with UV light, the two aryl groups, which are separated by a central ethene unit, rotate and undergo a cycloaddition reaction, forming a closed-ring isomer. This closed-ring form has a different electronic structure and therefore absorbs visible light, leading to a color change. The process is reversible; irradiation with visible light of an appropriate wavelength can induce the ring-opening reaction, returning the molecule to its original colorless or UV-absorbing state.

The structure of diarylethenes generally consists of two aromatic rings connected by a conjugated pi system, often containing an ethene moiety. The specific aromatic rings and substituents can be varied to tune the absorption wavelengths and photoreaction efficiencies. Diarylethenes are known for their thermal stability and fatigue resistance, meaning they can undergo numerous photochromic cycles without significant degradation. This makes them attractive for various applications, including optical data storage, molecular switches, and smart materials. Research continues to explore new diarylethene derivatives with improved properties for advanced technological uses.