Photochromism of single crystalline diarylethenes

Dithienylperfluorocyclopentenes were found to undergo reversible photocyclization in the crystalline phase. Both the open-form colorless and photogenerated closed-ring colored isomers were thermally stable even at 100 degrees C. Coloration/decoloration cycles could be repeated more than 100 times with keeping the crystal shape. Regular alignment of the colored isomers in the crystal was evidenced by the absorption measurement under linearly polarized light.