Mechanochemistry as a Tool for Crystallizing Inaccessible Solids from Viscous Liquid Components

The crystal structures of many organic compounds can be determined by growing single crystals using standard laboratory methods and collecting X-ray data using single-crystal X-ray diffraction. However, some organic compounds prove challenging to crystallize using standard methods. Here, we describe a strategy for crystallizing liquids using a solid component that facilitates crystallization of the components into a multicomponent solid. The method utilizes mechanochemistry as a key step in the synthesis of the crystals, which are otherwise difficult or impossible to obtain using standard solution-growth techniques. Spectroscopic characterization demonstrates a difference in products obtained from mechanochemistry and failed solution crystallizations. The crystals obtained using the method can also be used to seed subsequent crystallizations in solution when the solids are not obtainable without seed crystals. In addition to obtaining the first X-ray structures including three common pyridine ligands, the methods described provide a useful strategy for obtaining crystalline materials when the components do not crystallize using standard solution conditions or are viscous liquids/oils at room temperature.