Design and Synthesis of New Furan-Like Chalcone Crystals with Two Para-Substituents: 5MFTF and 5MFTN

Two novel chalcone crystals, 5MFTF (C15H11F3O2, P1) and 5MFTN (C14H11NO4, P1), were successfully synthesized by introducing trifluoromethyl and nitro substituents, respectively. Growth of the crystals was carried out by a slow evaporation solution method. The structures of the crystals were successfully verified by the results of 1H NMR, FT-IR, and powder XRD tests. The crystal stacking arrangements of 5MFTF and 5MFTN were characterized via a single-crystal X-ray diffraction (XRD) technique. The second-harmonic generation (SHG) measurements revealed that 5MFTF exhibited an SHG intensity 7.5 times that of potassium dihydrogen phosphate (KDP), while 5MFTN showed a SHG intensity 5.2 times that of KDP. The hyperpolarizability and FMOs were also calculated. In order to reveal the microscopic charge transfer mechanism in crystalline materials (5MFTF and 5MFTN), hole–electron analysis and interfragment charge transfer were calculated. 5MFTN crystal exhibited higher thermal decomposition temperatures compared to the other chalcone crystals (Tm ≈ 207 °C). All of these results indicate that the 5MFTF and 5MFTN crystals are promising for optical applications.