Photochromism of Heterocyclic Fulgides

Aiming at practical uses of photochromic compounds as data-storage media, electron-donating (e.g. p-dimethylaminophenyl) and conjugate chain (e.g. p-dimethylaminostyryl) substituted heterocyclic fulgides, e.g. 2-[1-(2-substituted 5-methyl-4-oxazolyl)ethylidene]-3-isopropylidenesuccinic anhydride and 2-[1-(5-substituted 2-methyl-3-thienyl)ethylidene or methlyene]-3-isopropylidenesuccinic anhydride, were prepared. The effect on photochromic performance was also investigated; it was clarified that substituents had effects on the red-shift and a significant increase in the color intensity of a colored form. However, the rate of the discoloration reaction was also affected, depressed, by the substituent.