Photochromism of novel [1]benzothien-2-yl fulgides

Novel [1]benzothien-2-yl fulgides have been synthesized. Under irradiation the compounds with R1=H undergo reversible Z/E-photoisomerization, the compound with a methyl group (R1=Me) at the methylidene bridge rearranges into the thermally stable colored ring-closed isomer.