3.1.3. DSC Analysis

As reported by Zhao Yanxiao [18], the DSC thermogram (Figure 5) of ARI exhibited two endothermic peaks and a small exothermic peak. The endothermic peak at 138.94 ◦C corresponded to the melting point of form III, while the second endothermic peak at 147.79 ◦C represented the melting point of form I, demonstrating that form III might be transformed to form I during the heating process. As expected, the DSC thermograms of ARI multicomponent crystals were distinct from those of ARI and CCF. A single melting endothermic peak was observed at 182.38 ◦C for the ARI-SAL salt, indicating the formation of pure solid phase. For the ARI-ADI salt acetone hemisolvate, a weak endothermic event of desolvation and a sharp melting endothermic peak were observed at 57.43 ◦C and 121.18 ◦C, respectively, which implied that it had a poor thermodynamic stability and may transform into a desolvated salt. As we intended, the ARI-ADI salt showed a single melting endothermic peak at 120.36 ◦C.

**Figure 5.** DSC thermograms of ARI, CCF, and its crystal salts.
