Simultaneous encapsulation: molecules held at close range.

Reversible encapsulation creates spaces where molecules are temporarily isolated from others in solution. Molecules are held within the space of the capsule for lifetimes ranging from milliseconds to hours, and conventional NMR spectroscopy can be used to report on the chemical and magnetic environment as well as the arrangement of the molecules in the encapsulation complex. The complexes self-assemble when, and only when, the spaces inside the capsules are appropriately filled. The weak intermolecular forces that hold these self-assemblies together allow equilibration of the encapsulation complexes at ambient temperatures and pressures in the liquid phase. When two or more molecules are simultaneously encapsulated, intermolecular phenomena are revealed in solution that cannot be observed by other methods. We describe here the unique behavior that emerges from molecules that are simultaneously encapsulated and includes new forms of stereochemistry, isomerism, and asymmetry inside capsules.