PerspectiveChemistry

A Versatile Molecular Trap Built from Hydrogen-Bonded Tiles

Science  22 Jul 2011:
Vol. 333, Issue 6041, pp. 415-416
DOI: 10.1126/science.1209090

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Summary

A molecule trapped in a cage—more benignly referred to as a “host-guest” complex—is a bit like a ship in a bottle. Somehow, the molecule got into the cage, and it is not always clear how that happened. Some preformed cages are simply filled with small molecules, as illustrated by molecules diffusing into a zeolite chamber. Some molecules template their own cage, like the polyhedral water clathrates that trap the methane of methane ice. The cage and its contents may self-assemble like the virus proteins around an RNA or DNA core. No one has designed a synthetic molecular cage with the elegance of a virus, but chemists are getting closer (13). On page 436 of this issue, Liu et al. (4) report a supramolecular cage of 20 separate ions that reliably self-assemble to trap a wide variety of guests of varying charge and composition. Most fascinating, the cage “forces” the formation of previously unknown metal-halogen clusters.