| Photochromic and electrochromic compounds are molecules that interconvert between two distinct structural forms, differing in their absorption spectra, when triggered with an appropriate light or electrochemical stimulus, respectively. 1,2-Dithienylcyclopentenes are photochromic compounds that reversibly interconvert between colourless ring-open and coloured ring-closed forms when irradiated with ultraviolet and visible light, respectively. A series of novel photochromic and electrochromic compounds, based on the dithienylcyclopentene skeleton, were synthesized and evaluated for potential use in molecular scale devices.; A series of covalently linked double 1,2-dithienylcyclopentene photochromic systems were prepared for potential use as high-density optical storage materials. Irradiation of the binary dithienylperhydrocyclopentene systems with ultraviolet light resulted in ring-closure of only one of the photochromic moieties, followed by quantitative production of a photostable side-product. The side-product, however, did not form as rapidly when the perfluorinated cyclopentene derivatives were irradiated with UV light.; Terthiophene oligomers were incorporated into the dithienylcyclopentene backbone in such a way that the linear π-conjugation of the terthiophene units were severed upon ring-cyclization and re-routed through the backbone of the molecule. This compound, as well as other 1,2-dithienylcyclopentene derivatives bearing either thiophene or phenyl groups on the carbon atoms involved in forming the new single bond in the ring-closing reaction were found to have both photochromic and unprecedented electrochromic properties. These compounds could be reversibly interconverted between their ring-open and ring-closed states using UV and visible light, respectively, and catalytically transformed from their ring-closed to their ring-open states through electrochemical or chemical oxidation. Unprecedented electrochemical ring-closing was also observed for two 1,2-bis(dithienyl)cyclopentene derivatives. The ring-opening reaction was accomplished by irradiation using visible light, however, the ring-closing reaction could be triggered by using either UV light irradiation or electrochemical oxidation.; A photochromic dithienylcyclopentene derivative was used to photoregulate helicene formation. A [7]-thiahelicene could be reversibly created and destroyed by alternate irradiation with ultraviolet and visible light respectively.; A new class of photochromic compounds based on the hexatriene backbone was developed which consisted of a thiophene ring, a perfluorocyclopentene ring, and a trisubstituted olefin. These systems reversibly undergo photoinduced ring-opening and ring-closing reactions when irradiated with UV and visible light, respectively. |
