Complexes within complexes: hydrogen bonding in capsules

Hydrogen bonds play an important role in molecular recognition, biomolecule stabilization and organocatalysis. Typically, individual hydrogen bonding interactions are weak and short-lived in solution but isolated in capsules the encounters are intense and prolonged. We report here the interactions of carboxylic acids and primary carboxamides in a number of different capsule environments. The preference for hetero- vs. homo-dimerization is interpreted in terms of the adaptation of the guests to the hosts' spaces and chemical surfaces.