Phosphorescent co-crystal assembled by 1,4-diiodotetrafluorobenzene with carbazole based on C-I•••π halogen bonding

1,4-diiodotetrafluorobenzene (1,4-DITFB) is an excellent halogen bonding donor and is used to assemble an organic phosphorescent co-crystal with carbazole in which 1,4-DITFB is expected to act as a functional synthon, the cement to link carbazole molecules by halogen bonding and heavy atom perturber to enhance phosphorescence of the emitter carbazole by spin-orbital coupling. The XRD reveals that the stoichiometry of (2 : 1) between 1,4-DITFB and carbazole occurs. An infinite chain is constructed by the C-I center dot center dot center dot pi halogen bonding and the pi center dot center dot center dot pi stacking of edge to edge between two 1,4-DITFB molecules is significant in maintaining stability of the 1D infinite chain. The inter-chain bonding includes C-H center dot center dot center dot I hydrogen bonding, H center dot center dot center dot F or F center dot center dot center dot F contacts to extend the infinite chain to 3D structure. The calculated halogen bonding energy is ca. 23.0 kJ mol(-1) based on the single crystal structure, indicating a strong halogen bonding. The co-crystal also is well characterized by powder XRD, FT-IR, Raman, and solid F-19 NMR spectroscopy. Moreover, the co-crystal as suspension microparticles can be very easily assembled in water by dropping water into an ethanol solution of 1,4-DITFB and carbazole. The C-I center dot center dot center dot pi halogen bonding of 1,4-DITFB with carbazole should be instructive to develop some phosphorescent nano-or micro-materials.