Polyoxometalate Catalyst Renders Nerve Agents Harmless

A new study describes a polyoxometalate (POM) catalyst that decomposes nerve agents, eliminating their harmful and lethal effects.

Researchers at Brookhaven National Laboratory (BNL; Upton, NY, USA) and Stony Brook University (SBU; NY, USA) conducted a study to investigate the decomposition process of the nerve agent Sarin and its simulant, dimethyl chlorophosphate (DMCP), using a zirconium polytungstate POM. To do so, they used x-ray photoelectron spectroscopy (XPS), a research technique that uses ultrabright x-rays to measure the elemental composition of a sample. They thus observed a change in the charge state of the zirconium atom in the POM molecule.

By comparing diffraction patterns, they found that the disordering of the zirconium-POM crystal lattice resulted in adsorption of the Sarin simulant molecules. Using computer models, they then showed that the resulting structural changes of the POM catalyst exposed zirconium atoms to Sarin, and that these interactions were responsible for the decomposition of DMCP by a tungstate monomerization process that activated nucleophilic hydrolysis. The study was published on April 19, 2019, in the Journal of Physical Chemistry Letters.

“Usually, a catalyst is a rigid structure that remains stable. Initially, this catalyst was a dimer, two big molecules connected by two bridging bonds. It looked like a bicycle with two wheels and a frame connecting them,” said lead author Anatoly Frenkel, PhD, of BNL and SBU. “What we understood after looking at the catalyst is that the bicycle broke into two 'wheels' and the 'frame' was cut. The process of breaking the dimer was equivalent to activating the catalyst.”

“Our work is part of an ongoing, multiagency effort to protect soldiers and civilians from chemical warfare agents,” concluded Dr. Frenkel. “The research requires us to understand molecular interactions on a very small scale, and to develop special characterization methods that are capable of observing those interactions. It is a very complex set of problems that also has a very immediate societal impact.”

Sarin is an extremely toxic synthetic organophosphorus compound generally considered as a weapon of mass destruction. A colorless, odorless liquid, it is an extremely potency nerve agent, with exposure lethal even at very low concentrations, and death occurring within ten minutes of direct inhalation of a lethal dose due to suffocation from lung muscle paralysis. People who absorb a non-lethal dose, but do not receive immediate medical treatment, may suffer permanent neurological damage.

Related Links:
Brookhaven National Laboratory
Stony Brook University