Synthesis and Photochromic Behavior of 5-Substituted Indolylfulgides

Abstract 1,2-Dimethylindolylfulgides with 5-methylthio, 5-methoxy, or 5-dimethylamino group on the indole ring were synthesized and their photochromic properties were examined. Electron donating substituents lengthened the absorption maximum of the colored form and decreased the quantum yields of the photoreactions. The colored form of the dimethylaminoindolyl-substituted fulgide has λmax at 673 nm, the longest absorption maximum wavelength ever known as that of a fulgide.