Polymorphism-dependent fluorescence of 9,10-bis(pentafluorobenzoyloxy)anthracene

Anthracene derivatives possessing pentafluorobenzoyloxy moieties at 9- and 10-positions showed polymorphism affording two types of fluorescent crystals with blue and bluish green fluorescence in their crystalline state, respectively. Their single crystal X-ray structures showed that the degree of overlap of anthracene moieties was responsible for the difference in fluorescence. Fluorescence in the crystalline state originated in the dimer emission deduced from their excitation spectra.