White phosphorus combusts violently in air, making it a dangerous agent, and one that has become controversial for its military uses.
Now Jonathan Nitschke at the University of Cambridge, UK, and his co-workers have constructed a molecular cage to defuse this version of phosphorus. The cage self-assembles in water from organic groups and iron ions. A solution of the cage can suck up solid white phosphorus, trapping its small, tetrahedral molecules within the cages' larger ones (pictured).
The cage doesn't prevent oxygen reaching the white phosphorus, but does stop it reacting because there isn't enough room within the cage for the normal products of the reaction to form.
Benzene can displace the incendiary molecule, releasing it from its confinement.
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Chemistry: Fire boxed. Nature 460, 15 (2009). https://doi.org/10.1038/460015b