Thermochromism of the crystals of 2,3-Di(p-chlorophenylthio)-1,4-naphthoquinone

The crystals of 2,3-di(p-chlorophenylthio)-l,4-naphthoquinone have the dimorphs of red and dark red forme. The crystal structure of red form has been determined by the X-ray diffraction method. The red form changes to the dark red form upon heating. Such thermochromism was studied by measuring the solid state CP/MAS and temperature variable IR absoption spectra, and the DSC of the red form of 2,3-di(p-chlorophenylthio)-l,4-naphthoquinone.