With this incredibly wide range of available synthetic strategies and reactions, COCs offer some of the highest levels of structural diversity of molecular capsules. The caveat to this is that the irreversibility of reactions can result in much reduced yields compared to alternative systems. Regardless, the versatility of COCs means they can be designed to be rigid or relatively flexible, of various sizes and geometries. They can also be rendered soluble in various media, and porosity in the solid-state can be tailored through substituents. In terms of characterising and studying POCs, solid-state analysis by SCXRD is common, as is the use of NMR and MS in solution.