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 la formed stoichiometric cocrystals with aromatic hydrocarbons, benzene (Bz) and naphthalene (Np), based on aryl-perfluoroaryl interactions. In crystal 1a/Bz (la:Bz = 2:1), a linear chain structure was constructed, in which each benzene molecule is sandwiched between pentafluorophenyl rings of two la molecules. In crystal 1a/Np (la:Np = 1:1), a discrete sandwiched structure was formed, in which two la molecules sandwich two naphthalene molecules between its pentafluorophenyl groups. In the la, 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.