**4. Conclusions**

ND and LP form two pseudo-polymorphs of multicomponent salt cocrystals. The first multicomponent crystal involves four water molecules, or a tetrahydrate, named NDPT. Meanwhile, the second consists of one water molecule, or a monohydrate, named NDPM. Both hydrates have a monoclinic lattice system. However, the monohydrate form was unstable and changed to NDPT easily under ambient condition. NDPT was a stable salt cocrystal even after breaking the structure after drying due to water loss; its structure recovered rapidly under ambient conditions. Moreover, NDPT structure was also stable under high humidity. Both salt cocrystals significantly increased the solubility and dissolution rate of the original starting material, ND, but NDPM was superior. Further research should hold continuously to observe other polymorphs and hydrates, which is still very challenging. The investigation of diffusion and absorption should also be carried out.

**Supplementary Materials:** The following are available online at http://www.mdpi.com/1999-4923/12/7/690/s1: S1: CIF crystal data of NDP monohydrate, S2: CIF crystal data of NDP tetrahydrate, S3: Diffractogram (1) and TG-thermogram (2) of ND and NDH.

**Author Contributions:** Conceptualization, I.N.; methodology, I.N., R.A.K., H.U., and A.H.; software, R.A.K. and A.H.; validation, I.N., R.A.K., A.H., and H.U.; formal analysis, I.N., R.A.K., W.A., and A.H.; investigation, I.N., R.A.K., and A.H.; resources, I.N. and H.U.; data curation, I.N., A.H., and H.U.; writing—original draft preparation, I.N., R.A.K., and H.U.; writing—review and editing, I.N., A.H., H.U., and W.N.A.; visualization, I.N., A.H., and W.N.; supervision, I.N. and H.U.; project administration, I.N. and W.N.; funding acquisition, I.N. and H.U. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by High Educational Directorate of Indonesia Education Ministry of Republic Indonesia—Research and Society Service Institution of Bandung Institute of Technology, Number 2/E1/KP.PTNBH/2020 (IN). A part of this study was performed in Tokyo Institute of Technology, Japan, and was supported by JSPS KAKENHI Grant Number JP17K05745 and JP18H04504 (HU).

**Acknowledgments:** This research was funded by High Educational Directorate of Indonesia Education Ministry of Republic Indonesia—Research and Society Service Institution of Bandung Institute of Technology, Number 2/E1/KP.PTNBH/2020 (IN). A part of this study was performed in Tokyo Institute of Technology, Japan, and was supported by JSPS KAKENHI Grant Number JP18H04504 and 20H04661 (HU).

**Conflicts of Interest:** The authors declare no conflicts of interest.
