Aiming at practical uses of photochromic compounds as data-storage media, electron- donating (eg p-dimethylaminophenyl) and conjugate chain (eg p-dimethylaminostyryl) substituted heterocyclic fulgides, eg 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 ...