Room‐Temperature Phosphorescence of Crystalline 1,4‐Bis(aroyl)‐2,5‐dibromobenzenes (Eur. J. Org. Chem. 3/2016)

The cover picture shows optical and phosphorescent images of 2,5‐dibromo‐1,4‐bis(4‐trifluoromethylphenylcarbonyl)benzene in crystals under ambient conditions with a simplified Jablonski diagram and the molecular structure of 1,4‐bis(aroyl)‐2,5‐dibromobenzene. The room‐temperature phosphorescence is observed only in crystals, but neither in solution nor in a doped polymer film. Thus, a class of the bis(aroyl)benzenes can serve as chromophores that exhibit crystallization‐induced room‐temperature phosphorescence. Intramolecular motion resulting in the energy loss in the triplet excited states is suppressed by several kinds of intermolecular interactions in crystals. Details are discussed in the article by M. Shimizu et al. on p. 467 ff . The authors would like to warmly thank Ms. Kuniko Kayama for artistic inspiration and assistance in preparation of this cover picture.