3.2.1. PXRD

The PXRD patterns were recorded for commercially available DPA, TA, and DPA:TA crystals obtained from slow solvent evaporation and DPA:TA salt obtained from the slurry method. The PXRD pattern of the salt is different from the DPA component, suggesting the formation of a new crystalline phase in the solid-state. (Figure 7). Furthermore, the peak position of the experimental PXRD pattern obtained from the slow solvent evaporation and the slurry method matched well with the simulated PXRD pattern obtained from the single-crystal X-ray structure, confirming the homogeneity of the sample and ruling out the presence of another phase. It also confirms that the single-crystal structure is representative of the bulk and that there is no phase transition between 93 K (at which the single-crystal structure was determined) and room temperature (at which the powder pattern was measured). The subtle differences could be due to the different data collection temperatures (for powder and a single crystal). Thus, a PXRD analysis of samples obtained by the slurring of DPA and TA in acetonitrile at 25 ◦C is matched very well to the DPA:TA salt obtained from the slow evaporation methods, which indicated a similar solid form of salt DPA:TA obtained from both methods.

**Figure 7.** Powder X-ray diffraction (PXRD) patterns of (**a**) commercial DPA, (**b**) TA, (**c**) simulated DPA:TA, (**d**) DPA:TA salt obtained from slurry method, and (**e**) DPA:TA salt obtained from slow solvent evaporation.
