*Article* **Entrapped Transient Chloroform Solvates of Bilastine**

**Cristina Puigjaner 1,\*, Anna Portell 1, Arturo Blasco 2, Mercè Font-Bardia <sup>1</sup> and Oriol Vallcorba <sup>3</sup>**


**Abstract:** The knowledge about the solid forms landscape of Bilastine (BL) has been extended. The crystal structures of two anhydrous forms have been determined, and the relative thermodynamic stability among the three known anhydrous polymorphs has been established. Moreover, three chloroform solvates with variable stoichiometry have been identified and characterized, showing that S3CHCl3-H2O and SCHCl3 can be classified as transient solvates which transform into the new chloroform solvate SCHCl3-H2O when removed from the mother liquor. The determination of their crystal structures from combined single crystal/synchrotron X-ray powder diffraction data has allowed the complete characterization of these solvates, being two of them heterosolvates (S3CHCl3-H2O and SCHCl3-H2O) and SCHCl3 a monosolvate. Moreover, the temperature dependent stability and interrelation pathways among the chloroform solvates and the anhydrous forms of BL have been studied.


**Citation:** Puigjaner, C.; Portell, A.; Blasco, A.; Font-Bardia, M.; Vallcorba, O. Entrapped Transient Chloroform Solvates of Bilastine. *Crystals* **2021**, *11*, 342. https://doi.org/10.3390/cryst 11040342

Academic Editor: Venu Vangala

Received: 14 March 2021 Accepted: 24 March 2021 Published: 28 March 2021

**Publisher's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

**Copyright:** © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

**Keywords:** solvate; polymorph; bilastine; crystal structure determination; single crystal X-ray diffraction; structure determination from powder diffraction
