Caged chemicals

A Cambridge University-led team of researchers has created a chemical cage that traps white phosphorus.

White phosphorus spontaneously ignites when exposed to the air, reacting with oxygen to form phosphorus pentoxide.

But now, a Cambridge University-led team of researchers has created a chemical cage that traps the white phosphorus, preventing the highly violent reaction from occurring.

The work could result in an array of hazardous chemicals being handled and transported more safely in future.

The research itself was carried out by a team consisting of Prasenjit Mal, Boris Breiner and Jonathan Nitschke at Cambridge University’s Department of Chemistry, together with Kari Rissanen from the University of Jyvaskyla in Finland.

The cage they developed does not exclude oxygen, but restricts the reaction of oxygen with the phosphorus through a constrictive mechanism that does not allow the oxygen and phosphorus to form the phosphorus pentoxide that would be too large for the cage’s cavity.

The practical implications of the research are impressive: the technique of ‘caging’ individual molecules of the substance allows it to be manipulated and stored with greater safety, and it also has the potential to be used to tame other dangerous chemicals.

The crystal structure of the white-phosphorus containing cage

Dr Nitschke says: ‘It is foreseeable that our technique might be used to clean up a white-phosphorus spill, either as part of an industrial accident or in a war zone. In addition to its ability to inflict grievous harm while burning, white phosphorous is very toxic and poses a major environmental hazard.’