On the configuration of 4,4′,6,6′-tetraphenyl-2,2′-dithiopyrylene

The title compound showed in its UV-VIS absorption spectra large red shifts of bands from solution to crystal indicating a pronounced intermolecular interaction between the dithiopyrylene π-electron systems. Dipole moment measurement in benzene solution gave a dipole moment value of 1.90 D which offers a direct evidence for the molecule in cis-configuration.