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.