PHOTOCHROMIC REACTIONS OF BIS(2-THIENYL) PERFLUOROCYCLOPENTENES

Photochromic reactivities and the absorption maxima of dithienylethene s were found to depend on the connecting position of the thiophene rin gs to the ethene moiety. When thiophene rigns are connected at 2-posit ion, the absorption maxima of the open-ring form showed bathochromic s hifts. Substitution of aromatic rings to the 5 and 5'-positions of the thienyl rings shifted the absorption band of the open-ring form to a longer wavelength and decreased the cyclization quantum yield. When 4- (N,N-diethylamino) phenyl rings were used as the aryl groups, the phot ochromic reaction was not observed. By the addition of acid, photo-rea ctivity was recovered. The photogenerated closed-ring form has the abs orption at a shorter wavelength than the open-ring form.