Destruction of chemical warfare agents using metal–organic frameworks

Abstract

Chemical warfare agents containing phosphonate ester bonds are among the most toxic chemicals known to mankind. Recent global military events, such as the conflict and disarmament in Syria, have brought into focus the need to find effective strategies for the rapid destruction of these banned chemicals. Solutions are needed for immediate personal protection (for example, the filtration and catalytic destruction of airborne versions of agents), bulk destruction of chemical weapon stockpiles, protection (via coating) of clothing, equipment and buildings, and containment of agent spills. Solid heterogeneous materials such as modified activated carbon or metal oxides exhibit many desirable characteristics for the destruction of chemical warfare agents. However, low sorptive capacities, low effective active site loadings, deactivation of the active site, slow degradation kinetics, and/or a lack of tailorability offer significant room for improvement in these materials. Here, we report a carefully chosen metal-organic framework (MOF) material featuring high porosity and exceptional chemical stability that is extraordinarily effective for the degradation of nerve agents and their simulants. Experimental and computational evidence points to Lewis-acidic Zr(IV) ions as the active sites and to their superb accessibility as a defining element of their efficacy.

Tuning the Surface Chemistry of Metal Organic Framework Nodes: Proton Topology of the Metal-Oxide-Like Zr6 Nodes of UiO-66 and NU-1000

“…Assessing such a situation would require simulations with explicit solvent (and a suitable model for computing Zr-O interactions) that go beyond the scope of this work, but this is a topic meriting further study. It is known that fully dehydrated NU-1000 reverts to fully hydrated NU-1000 (i.e., all faces having site 1 topology) when exposed to benchtop humidity for a period of several weeks, 37 and so we are confident that the barrier is indeed kinetic in nature.…”

Swellable functional hypercrosslinked polymer networks for the uptake of chemical warfare agents

“…Toluene (10 mmol) was added to anhydrous 1,2-dichloroethane (10 mL) under a flow of nitrogen, followed by formaldehyde dimethyl acetal (15,16,17,19,20,23,25,27,30,40, or 50 mmol for 1.5, 1.6, 1.7, 1.9, 2, 2.3, 2.5, 2.7, 3, 4, or 5 equivalents of FDA, respectively). An equimolar amount of iron(III) chloride (15,16,17,19,20,23,25,27,30,40, or 50 mmol) was added and the reaction mixture heated at 80°C for 18 hours. After cooling the solid product was removed by filtration and washed with methanol several times.…”

Experimentalists and theorists need to talk

“…It is important that the MOF node cleaves one bond (P-S) rather than another (P-O) to avoid producing a toxic chemical 3 . Calculations based on 'density functional theory' , which explore the stabilities of various chemicals produced during a reaction, identified this MOF as a potential catalyst without researchers having to perform many hazardous lab tests 4 .…”