Reversible encapsulation of terminal alkenes and alkynes

Molecular encapsulation is a modern form of recognition in which a host completely surrounds a guest molecule. Unlike earlier covalent systems, reversible assembly allows the study of these complexes at equilibrium under ambient conditions. We show here that self-assembled capsules held together by hydrogen bonds surround a series of alkenes and alkynes that fill the space properly. These guests are frequently found in contorted conformations that reduce their length in order to fit inside and then make appropriate contacts with the capsule.