Crystal Structure, Characterization and Enhanced Solubility of Ibuprofen by 2-Methylimidazolium Salt

Novel crystalline forms of ibuprofen (IBU) with 2-methylimidazole (2MI) in a 1: 1 molar ratio was synthesized by liquid-assisted grinding technique and characterized by single-crystal X-ray diffraction, infrared spectral (IR), powder X-ray diffraction (PXRD), differential scanning calormetry (DSC) and Hirshfeld surface analysis. The structure of IBU-2MI salt is assembled via N(1)-H(1)(+)center dot center dot center dot O1 and N(2)-H(2)(+)center dot center dot center dot O(2) hydrogen bonds to form the zigzag-like 1D chain structure. The original purpose was to solve the pH-dependent solubility defect of ibuprofen, and the result of pH dependent solubility experiments showed that the IBU-2MI salt had a better solubility at the wide range of pH 4.00 to 9.18. Furthermore, the solubility of IBU-2MI salt exhibits a dramatic increase (30-fold) in aqueous mediums.