Photochromism of Furylfulgide in a Single-crystalline Phase

(E)-2,5-Dimethyl-3-furylethylidene(isopropylidene)succinic anhydride (1E) was found to undergo photochromism in the singlecrystalline phase. Upon irradiation with 366-nm light, the single crystal turned red. When the photogenerated colored crystal was observed under polarized light, the red color intensity changed by rotating the crystal. The colored crystal was stable at room temperature.