Speaker:  Dr Michael Grunweld, Department of Chemistry, The University of Utah, USA  

Host:   Dr Asaph Widmer-Cooper   [Map]

Abstract:

Predicting the crystallization behavior of solutions of chiral molecules is a major challenge in the chemical sciences. In this talk, I will describe our recent theoretical efforts to understand chiral crystallization with the help of a family of coarse-grained models of chiral molecules with a broad range of molecular shapes and interactions. Our simulations reproduce the experimental crystallization behavior of real chiral molecules, including racemic and enantiopure crystals, as well as amorphous solids. Using efficient algorithms for the packing of shapes, we enumerate millions of low energy crystal structures for each model and analyze the thermodynamic landscape of polymorphs. In agreement with recent conjectures, our analysis shows that the ease of crystallization is largely determined by the number of competing polymorphs with low free energy. We find that this number, and hence crystallization outcomes, depend on molecular interactions in a simple way: Strongly heterogeneous interactions across molecules promote crystallization and favor the spontaneous resolution of racemic mixtures.