The Polymorphs of Diacetylcurcumin (DAC)

Two new monoclinic and triclinic polymorphs of diacetylcurcumin are reported in addition to the previously known polymorph (monoclinic, space group P21). These polymorphs result from different solvent mixtures that were successfully established. The solid-state NMR (CP-MAS) and X-ray studies allowed unambiguous authentication of polymorph 2 (canoe-shaped, P21/n) and the concomitant polymorph 3 (balloon-shaped, P−1). We demonstrate that morphological crystal analysis under a microscope, combined with ATR-IR, is a rapid and inexpensive method for exploring the polymorphic landscape of curcuminoids. This contribution highlights the progress in curcumin derivative research and should inspire fellow chemists and materials scientists to explore further.