1,2-Bis[5-(9-ethyl-9H-carbazol-3-yl)-2-methyl-thio-phen-3-yl]-3,3,4,4,5, 5-hexa-fluoro-cyclo-pentene

The title compound, C ₄₃H ₃₂F ₆N ₂S ₂, is a new symmetrical photochromic diaryl-ethene derivative with 9-ethyl-carbazol-3-yl substituents. The mol-ecule adopts a photoactive anti-parallel conformation [Irie (2000). Chem. Rev. 100, 1685-1716; Kobatake et al. (2002). Chem. Commun. pp. 2804-2805], with a dihedral angle between the mean planes of the two thio-phene rings of 56.23 (6)°. The distance between the two reactive C atoms is 3.497 (3) Å. In the crystal, two molecules are associated through a pair of C - H⋯F inter-molecular hydrogen bonds, forming a centrosymmetric dimer. Dimers are linked by weak π-π inter-actions [centroid-centroid distance = 3.8872 (13) Å], forming chains along the c axis.