Aryl−Perfluoroaryl Interaction in Photochromic Diarylethene Crystals

A diarylethene derivative with two pentafluorophenyl groups, 1,2-bis(2-methyl-5-pentafluorophenyl-3-thienyl)perfluorocyclopentene ( 1a ), was synthesized in an attempt to prepare photochromic single crystals with well-controlled photochromic properties by utilizing intermolecular noncovalent aryl−perfluoroaryl interactions. Compound 1a formed stoichiometric cocrystals with aromatic hydrocarbons, benzene ( Bz ) and naphthalene ( Np ), based on aryl−perfluoroaryl interactions. In crystal 1a / Bz ( 1a: Bz = 2:1), a linear chain structure was constructed, in which each benzene molecule is sandwiched between pentafluorophenyl rings of two 1a molecules. In crystal 1a / Np ( 1a: Np = 1:1), a discrete sandwiched structure was formed, in which two 1a molecules sandwich two naphthalene molecules between its pentafluorophenyl groups. In the 1a, 1a / Bz, and 1a / Np crystals, the diarylethene molecules underwent photochromic reactions. Absorption properties of the photogenerated closed-ring isomers were different from each other depending on conformations of the diarylethene molecules packed in the crystals.