He calls the resulting molecule a "carcerand,' from the Latin word for a prison.
"But the space inside a carcerand is like no other chemical environment, and the guest molecule finds itself locked up for life.'
Strong acids, for example, tend to break down the bonds of a carcerand cage, releasing any trapped molecules.
Last year, Cram reported linking two bowl assemblies to make the first "molecular cells," which he also calls carcerands because small molecules get trapped inside when the bowl rims meet.
Cram expects next to build new carcerands by linking a pair of box cavities to make an elongated box with a bulge in the middle.
Cram envisions using cavitands and carcerands to shuttle drugs to diseased cells, as slow-release pesticide delivery systems, and as novel liquid crystals in which the carcerands crystallize in place while their molecular prisoners are free to respond to electric fields.