J. Phys. IV France 11 (2001) Pr10-253-Pr10-259
Solvent exchange between dimethylsulfoxide and water in the dexamethasone acetate structureF. Mallet1, S. Petit1, M.-N. Petit1, P. Cardinaël1, P. Billot2, S. Lafont2 and G. Coquerel1
1 Unité de Croissance Cristalline et de Modélisation Moléculaire (UC2M2), UPRES EA 2659, IRCOF, Université de Rouen, rue Tesnière, 76821 Mont-Saint-Aignan cedex, France
2 AVENTIS PHARMA, Process Development, 102 route de Noisy, 93235 Romainville cedex, France
Dexamethasone acetate can crystallize as a DSMO (dimethylsulfoxide) solvate with a stoechiometry (1 : 1), and its crystal structure shows the presence of channels containing the DMSO molecules. When single crystals of this solvate are immersed in water according to the methodology proposed by Nordhoff & Ulrich , the exchange between DMSO and water occurs, associated with the formation of needle-like crystals (whiskers). The phase obtained is a sesquihydrate, instead of the monohydrated variety already described, and the whiskers are formed preferentially on high energy sites (defects, edges). These observations are discussed with the aim to propose a mechanism describing both the desolvation step and the formation of the whiskers, and seem to be consistent with a mechanism of destructive-reconstructive transformation.
© EDP Sciences 2001