Phosphorescent π-Hole···π Bonding Cocrystals of Pyrene with Halo-perfluorobenzenes (F, Cl, Br, I)

Seven novel cocrystals of pyrene with halo-perfluorobenzenes (F, Cl, Br, I) were successfully prepared and well characterized by X-ray single-crystal diffraction. The stoichiometries of pyrene to halo-perfluorobenzene were all 1:1. The similar sandwich structures comprise pyrene and halo-perfluorobenzene alternatively stacked via π-interactions by which pyrene molecules are isolated from each other as expected instead of the dimer in the pure pyrene crystal. The phosphorescence or delayed fluorescence was, therefore, lightened under heavy atom perturbation from halo-perfluorobenzene. Moreover, based on the consideration of surface electrostatic potential (SEP) of interacting molecules, the π-interaction between halo-perfluorobenzenes with positive SEP and pyrene with negative SEP is more appropriately named the π-hole···π bond, which should be significant as a new strategy in assembling organic phosphors.