Size-Control by Anion Templating in Mechanochemical Synthesis of Hemicucurbiturils in the Solid State

Self-organization is one of the most intriguing phenomena of chemical matter. While the self-assembly of macrocycles and cages in dilute solution has been extensively studied, it remains poorly understood in solvent-free environments. Here, we provide the first example of using anionic templates to achieve selective assembly of differently sized macrocycles in a solvent-free system. Using the acid-catalyzed synthesis of cyclohexanohemicucurbiturils as a model system, we demonstrate size-controlled quantitative synthesis of 6- or 8-membered macrocycles, taking place through spontaneous anion-directed re-organization of mechanochemically-obtained oligomers in the solid state.