Syntheses and characterizations of two curcumin-based cocrystals

•Two pharmaceutical cocrystals have been prepared.•JUC-C14 displays a 1D chain.•The di-keto structure of curcumin in JUC-C15 is rarely reported.

Two pharmaceutical cocrystals, named Jilin University China–Cocrystal-14 (JUC-C14) and Jilin University China–Cocrystal-15 (JUC-C15), which were composed of curcumin and 4, 4′-bipyridine-N, N′-dioxide, were successfully prepared by crystal engineering strategy. The crystal structures of the two cocrystals were solved and refined by single crystal X-ray diffraction. It is indicated that the crystal structures are assembled via intermolecular interactions including hydrogen bonds and π⋯π stacking. Additionally, in the structure of JUC-C15 curcumin existed in a di-keto form which is rare in other reported curcumin polymorphs. Power X-ray diffraction, Fourier-transform infrared spectra, thermogravimetric analyses and differential scanning calorimetry were executed as well to confirm the formation of the cocrystals.

Graphical abstractTwo pharmaceutical cocrystals, JUC-C14 and JUC-C15, which were composed of curcumin and 4, 4′-bipyridine-N, N′-dioxide, were successfully prepared under the similarly synthetic conditions. It is indicated that JUC-C14 exhibits 1D chain structure, while JUC-C15 is a 2D net structure linked via hydrogen bonds and π⋯π packing interactions. Additionally, in the structure of JUC-C15 curcumin existed in a di-keto form which is rare in other reported curcumin polymorphs.Figure optionsDownload full-size imageDownload as PowerPoint slide