Photochromism of Dithienylethenes with Electron-Donating Substituents

Article abstract of DOI:10.1021/jo00130a035

Bis(2,4-dimethyl-5-phenylthiophene-3-yl)perfluorocyclopentenes having hydrogen, methoxy, diethylamino, or cyano substituents at para-positions of the phenyl groups were synthesized to reveal the effect of the substitution on the absorption coefficient ε of the closed-ring forms and the photochemical reactivity.Electron-donating substituents, such as methoxy or diethylamino groups, were found to be effective to increase the absorption coefficient and to decrease the ring-opening quantum yield.The cyclization quantum yield was scarely affected by the substitution.The conversion from the open- to the closed-ring forms of the diethylamino-substituted compound in the photostationary state under irradiation with 313 nm light was close to 100percent.