Electrochromism in photochromic dithienylcyclopentenes.

Both photochromic and unprecedented electrochromic properties have been observed for a class of 1,2-bis(3-thienyl)cyclopentene derivatives bearing either a thiophene or a phenyl group attached to the reactive carbon centers. These compounds can be interconverted between their colorless ring-open and colored ring-closed states using UV and visible light, respectively. They can also be catalytically transformed from their ring-closed states to their ring-open states through electrochemical or chemical oxidation.