Synthesis, crystal growth, structure and photophysical properties of decafluoroanthracene and its co-crystals with polycyclic arenes

A series of 1:1 co-crystals of decafluoroanthracene with naphthalene, anthracene, tetracene, pyrene, perylene and triphenylene were grown and characterised using single-crystal X-ray diffraction at low and ambient temperature, (polarisation-dependent) fluorescence spectroscopy, and quantum mechanical computations. All of the molecular co-crystal structures are built from infinite stacks of alternating arene and decafluoroanthracene molecules representing the arene-perfluoroarene supramolecular synthon. Intermolecular interactions and packing features are discussed in detail. As a by-product, the heterodimer of tetracene and decafluoroanthracene was obtained after UV-light irradiation of a solution of the monomers, and structurally characterised. The fluorescence properties of the co-crystals of decafluoroanthracene with naphthalene, tetracene, pyrene, perylene and triphenylene are similar to those of one of their components with only a small bathochromic or hypsochromic shift. This shows that the interaction between the components is weak and fits well into the picture of an arene-perfluoroarene interaction. An exception is 1:1 anthracene:decafluoroanthracene, which shows a bathochromic shift of both excitation and especially emission spectra of the co-crystal compared to those of its components, which indicates weak charge transfer coupling already in the ground state followed by an exciplex-like emission.