3.3.1. Crystal Habit Observation

The crystal morphology was observed as simple identification, which then should be analyzed thoroughly with the more precise solid analysis instruments. Based on the screening data, cocrystals were collected by dissolving the (1:1) molar ratio of NDH–LP mixture in the first condition explained in the Methods section. It was observed that the crystallization of NDP from all solvents occurred fast (less than 24 h) under room temperature and yielded a similar habit and different from the starting materials. As a visualization, Figure 2 shows the crystal picture of the rectangular NDH (a), needle-shaped LP (b), and a cylindrical rods-shaped NDP (c). The different crystal habit of diclofenac–sodium–proline (NDP) from the starting material may indicate the new phase formation, which then should be confirmed thoroughly, by solid characterization using FTIR, PXRD, DSC/DTA/TG, and SCXRD.

**Figure 2.** Crystal morphology under a binocular microscope of (**a**) diclofenac sodium hydrate (NDH), (**b**) L-proline (LP), and (**c**) diclofenac–sodium–proline cocrystal (NDP). All recrystallizations were used ethanol solvent 95% under ambient conditions (72 ± 2% RH/25 ± 2 ◦C).
