Molecular Encapsulation beyond the Aperture Size Limit through Dissociative Linker Exchange in Metal-Organic Framework Crystals

Under linker exchange conditions, large guests with molecular diameters 34 times the framework aperture size have been encapsulated into preformed nanocrystals of the metalorganic framework ZIF-8. Guest encapsulation is facilitated by the formation of short-lived open states of the pores upon linker dissociation. Kinetic studies suggested that linker exchange reactions in ZIF-8 proceed via a competition between dissociative and associative exchange mechanisms, and guest encapsulation was enhanced under conditions where the dissociative pathway predominates.