Study of the thermal behavior of choline ibuprofenate using differential scanning calorimetry and hot-stage microscopy

The phase transformations in choline ibuprofenate, [chol][ibu], have been studied by differential scanning calorimetry (DSC) and hot-stage microscopy (HSM). Two crystalline forms, α and β, were identified that are very different in their thermal behavior, and thus probably very different in their crystal structures. The melting temperatures of the two crystal polymorphs differ as much as 50°. The higher temperature polymorph, α, presents a sharp and fast crystallization process, while the melting transformation displays a very slow dynamics. The β polymorph forms on cooling through a broad crystal-to-crystal transformation, and displays a melting process that is sharp compared with that of α polymorph.