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Boffins 'cage the demon' of white phosphorus

Moleculo-prison could neutralise hellfire weapon

Cambridge boffins have discovered a crafty molecular "cage" which can be used to imprison the "demon" chemical, white phosphorus, famous for burning inextinguishably and for its sometimes questionable military uses. Cleanup and transport of white phosphorus should now become much simpler and safer.

Phosphorus, as the Cambridge scientists note, has been known for centuries for its tendency to burst into flame on exposure to air. Even submerging burning phosphorus in water doesn't put it out properly - it merely slows combustion down, depending on the amount of oxygen in the water. Once the chemical is removed - perhaps just partially removed - from the water it's liable to start blazing again unpredictably as it dries out.

But phosphorus is useful stuff, handy for making weedkillers, insecticides and fertilisers. It's also popular for military use: phosphorus creates battlefield smokescreens much faster and better than any other filler, and at sea its ability to keep burning vigorously even semi-immersed makes it popular for flares and markers.

As a result, most armed forces have an array of white-phos munitions in their armouries - ranging from grenades up to heavy artillery shells. Though WP isn't designed or intended as an anti-personnel weapon - you would normally be able to inflict more casualties using the same weight of regular blast/frag rounds - it has shocking and nasty effects if purposely or accidentally used as such. Blazing particles of phosphorus can burn their way into a victim's body, where they keep on flaming and inflict excruciating pain.

Clearing up partially-burned or unexploded phosphorus rounds is particularly troublesome and hazardous owing to the tendency of the stuff to reignite when moved or disturbed. As a rule of thumb one in ten of any kind of munition doesn't function as designed, so there's always cleanup to do - and with phosphorus weapons, even a munition which works to spec will normally leave unburned particles of the chemical lying around afterwards.

An instance of this is the procedure followed by Royal Navy disposal teams dealing with the large partially-functioned phos markers which commonly wash up on UK beaches*. The responding divers generally prefer to wrap the entire munition in explosives on the spot and detonate them, so completely incinerating any remaining filler. (This follows incidents where markers being moved by hand or vehicle for disposal elsewhere burst into flame inconveniently.)

But now, Cambridge stinks brainboxes Prasenjit Mal, Boris Breiner and Jonathan Nitschke - collaborating with Finnish fellow-boffin Kari Rissanen - have invented a cunning new method for dealing with phosphorus. It seems that one can combine formyl-pyridine and diaminobiphenyl disulfonate with iron to form a molecular tetrahedron with a central void space in its middle. This four-sided "cage" can be made to form around molecules of phosphorus, locking them up so that they can't combine with oxygen.

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