Crystal engineering - nucleation, the key step

In the world of crystal engineering in which the focus of effort is on the assembly of molecular species by crystallisation, surprisingly little attention has been paid to the actual nucleation and crystallisation processes involved. this Highlight explores the structural aspects of the nucleation process in a range of small molecule systems. It uses a combination of thermodynamic, structural and modelling approaches in order to progress our understanding of the link between liquid phase molecular assemblies, which constitute crystal growth units, and their solid state counterparts, the supramolecular synthons.