Dynamics of supramolecular capsule

Abstract

Encapsulation complexes are molecular hosts that completely surround their guests. The hosts are self-assembled reversibly through weak intermolecular forces such as hydrogen bonds. To understand the thermodynamic and kinetic behavior of encapsulation, we have been using nuclear magnetic resonance methods for study of these systems in solution. Through our investigations with various types of hydrogen-bonded capsules, we have found that these assemblies exist on timescales of milliseconds to hours, long enough for many types of interactions and even reactions to take place within them. Furthermore, extensive study of the encapsulation and guest exchange processes revealed a guest exchange mechanism involving partial disruption of the hydrogen-bonded seam by conformational changes, rather than complete dissociation of the capsule. Through the thermodynamic and kinetic studies of supramolecular capsules, we have learned how molecules behave through weak interaction, which may give us some hint of how biological systems organize themselves.