Ibuprofen-nicotinamide cocrystal polymorphs: terahertz spectroscopy and DFT calculations

In this paper, two IBU-NIC cocrystal polymorphs of ibuprofen (IBU) and nicotinamide (NIC) were synthesized by melt recrystallization, solution evaporation and solvent milling, respectively. IBU, NIC, physical mixtures and their corresponding two cocrystals were characterized by terahertz (THz) spectroscopy. In addition, the theoretical structures of the two cocrystals of IBU-NIC were optimized and simulated by density functional theory (DFT) using Gaussian 16 software to obtain rich vibration mode information. By comparing the simulated results with the experimental results, the most reasonable molecular structures and vibrational modes for the preparation of IBU-NIC cocrystal polymorphs could be determined.