title: Structural Aspects of Solid Solutions of Enantiomers.
abstract: A mixture of two enantiomers can crystallize according to three types of heterogeneous equilibria: a racemic compound (a 1:1 stoichiometric compound), a conglomerate (a physical mixture of particles with opposite chirality) or, more rarely, as a solid solution (a crystalline architecture exhibiting a lack of chiral discrimination with respect to the two enantiomers). Due to the scarce occurrence of solid solutions, only a few examples of such behavior are known, and even fewer systems have been investigated by means of single crystal X-ray diffraction. Yet, preliminary work performed in the 1970s by several research teams revealed that structural investigations of solid solutions could provide valuable insights into chiral discrimination mechanisms at the crystal lattice scale. In the present paper, our aim is to review published cases of enantiomeric solid solutions for which both melting phase diagrams and crystal structures are available in order to analyze the lack of chiral discrimination associated to these phases. Our methodology consists in considering both the molecular and crystallographic aspects of stereoselectivity with the final aim of identifying structural criteria responsible for the occurrence of solid solutions. The experimental conditions allowing access to solid solutions will also be considered in light of these structural criteria.
authors: Laboratoire SMS-EA3233, Université de Rouen, Place Emile Blondel, F-76821, Mont-Saint-Aignan Cedex, France. clement.brandel@univ-rouen.fr.
authors: Clément
authors: C
authors: Brandel
authors: . samuel.petit@univ-rouen.fr.
authors: Samuel
authors: S
authors: Petit
authors: Yohann
authors: Y
authors: Cartigny
authors: Gérard
authors: G
authors: Coquerel
mesh_terms: D003460:Crystallization; D015394:Molecular Structure; D004364:Pharmaceutical Preparations / Q000737:chemistry*; D012996:Solutions; D013237:Stereoisomerism
chemical_list: D004364:Pharmaceutical Preparations; D012996:Solutions