Volume 179, 2015

Formation of new polymorphs without any nucleation step. Desolvation of the rimonabant monohydrate: directional crystallisation concomitant to smooth dehydration

Abstract

Rimonabant monohydrate can be dehydrated at 100 °C or above with complete loss of structural information; in this case the amorphous material can lead to nucleation and crystal growth. The water molecules can also be removed by a smooth process below Tg (78 °C) of the anhydrous phase. In that latter process there is a structural filiation between the mother phase and the daughter phase. The solvent molecules escape from the mother structure by using a network of specific channels; the new non-solvated material undergoes a relaxation process similar to a directional crystallization. By this soft mode of desolvation inside a material which has a very limited mobility, the nucleation of a non-solvated material can be avoided. The structural information contained in the mother phase is not used as a template for crystal growth but it is more a progressive rearrangement of the new desolvated material towards the nearest well in energy. Thus, a metastable new polymorph of a non-solvated component can be obtained by: (i) the crystallization of the component as a solvate and (ii) a smooth desolvation at T < Tg. Other parameters liable to interfere with that transmission of structural information are discussed.

Associated articles

Supplementary files

Article information

Article type
Paper
Submitted
17 Nov 2014
Accepted
07 Jan 2015
First published
08 Jan 2015

Faraday Discuss., 2015,179, 475-488

Author version available

Formation of new polymorphs without any nucleation step. Desolvation of the rimonabant monohydrate: directional crystallisation concomitant to smooth dehydration

B. Fours, Y. Cartigny, S. Petit and G. Coquerel, Faraday Discuss., 2015, 179, 475 DOI: 10.1039/C4FD00222A

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