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 pi-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 pi-interaction between halo-perfluorbenzenes with positive SEP and pyrene with negative SEP is more appropriately named the pi-hole center dot center dot center dot pi bond, which should be significant as a new strategy in assembling organic phosphors.