Spectroscopic Characterization of Intermolecular Interactions in Solution and Their Influence on Crystallization Outcome

Crystallization from solutions is an important technique for a wide range of industries. One of the prime requirements for crystallization is that molecular aggregation or clustering occurs prior to the formation of stable nuclei. Despite this, very little work has been carried out to investigate the nature of supersaturated solutions and the structure of prenucleation clusters. In this study, we have probed molecular assemblies in solution, using spectroscopic techniques, to search for structural features common to both solutions and solids. For the systems studied, it was found that, although solute−solute interactions could be detected in solution, there was generally a limited relationship with the solid forms, and therefore, these assemblies were not predictive of the polymorph initially crystallized.