High-Convertible Photochromism of a Diarylethene Single Crystal Accompanying the Crystal Shape Deformation

We designed and fabricated thin single-microcrystals of a photochromic diarylethene, 1,2-bis(2-methoxy-5-phenyl-3-thienyl)perfluorocyclopentene, which exhibits photochromic reactions up to high conversion in high efficiency because the diarylethene molecule has extremely small photocycloreversion quantum yield. The thin microcrystals prepared on glass plates by sublimation underwent photochromism upon alternating irradiation with ultraviolet and visible light. The photocyclization reaction proceeded with more than 90% conversion in the crystalline phase, keeping the crystallinity. In addition to the high-convertible photochromic reaction in the crystalline phase, the crystals were found to exhibit the shape changes, such as contraction, bending, and separation, depending on the thickness of the crystal and the irradiation method with ultraviolet light. The intermolecular interaction between the photogenerated closed-ring isomers plays a significant role in deforming the crystal.