Butterfly-shaped diphenylpyrimidine molecule: Tunable photophysical properties by molecular self-assembly pathways

To understand the relationships between chemical structures, molecular packing structures, and photophysical properties of organic materials, a butterfly shaped diphenylpyrimidine molecule (abbreviated as DPP-6C₁₂) was newly synthesized [Park, M.; Choi, Y.-J.; Kim, D.-Y.; Hwang, S.-H.; Jeong, K.-U. Cryst. Growth Des. 2015, 15, 900-906]. By breaking the molecular symmetry and coplanarity of DPP-6C₁₂, peculiar monotropic phase transitions were observed. Based on two-dimensional wide-angle X-ray diffraction and selected area electron diffraction, the molecular packing structures of ordered phases were identified, which were further confirmed by the computer simulations in the real and reciprocal spaces. Finally, we demonstrated that the photophysical properties of DPP-6C₁₂ can be tuned by controlling the molecular packing structures with simple thermal treatments.