Novichoks are a novel class of nerve agents (also referred to as the A-series) that were employed in several poisonings over the last few years. This calls for the development of novel countermeasures that can be applied in protective concepts (e.g., protective clothing) or in decontamination methods. The Zr metal−organic framework MOF-808 has recently emerged as a promising catalyst in the hydrolysis of the V-and G-series of nerve agents as well as their simulants. In this paper, we report a detailed study of the degradation of three Novichok agents by MOF-808 in buffers with varying pH. MOF-808 is revealed to be a highly efficient and regenerable catalyst for Novichok agent hydrolysis under basic conditions. In contrast to the V-and G-series of agents, degradation of Novichoks is demonstrated to proceed in two consecutive hydrolysis steps. Initial extremely rapid P−F bond breaking is followed by MOF-catalyzed removal of the amidine group from the intermediate product. The intermediate thus acted as a competitive substrate that was rate-determining for the whole two-step degradation route. Under acidic conditions, the amidine group in Novichok A-230 is more rapidly hydrolyzed than the P− F bond, giving rise to another moderately toxic intermediate. This intermediate could in turn be efficiently hydrolyzed by MOF-808 under basic conditions. These experimental observations were corroborated by density functional theory calculations to shed light on molecular mechanisms.

In the case of an incident with nerve agents, the timely and ready detection and identification of such a substance on suspected surfaces is essential. However, the detection of low levels of nerve agents on a surface is a considerable challenge for conventional detection equipment, especially with VX, a highly toxic nerve agent with low volatility. Here, we report the development of a metal–organic framework (MOF)/fabric composite that gives a rapid, visual, and sensitive color response when pre-wetted and rubbed over a VX-contaminated surface. The fabric is composed of cotton textile modified with the zirconium-based MOF MOF-808 that possesses a bidentate reactive dye, ditopic 5,5-dithiobis­(2-nitrobenzoic acid) (DTNB), on its nodes. The crystal structure of DTNB@MOF-808 showed that DTNB bridges between two adjacent nodes in MOF-808. The colorless composite changes to bright orange upon contact with VX as a result of the degradation of VX and the concomitant reaction of the dye with a VX degradation product in the MOF pores.

Organophosphorus nerve agents (OPNAs) are highly toxic compounds inhibiting cholinergic enzymes in the central and autonomic nervous systems and neuromuscular junctions, causing severe intoxications in humans. Medical countermeasures and efficient decontamination solutions are needed to counteract the toxicity of a wide spectrum of harmful OPNAs including G, V and Novichok agents. Here, we describe the use of engineered OPNA-degrading enzymes for the degradation of various toxic agents including insecticides, a series of OPNA surrogates, as well as real chemical warfare agents (cyclosarin, sarin, soman, tabun, VX, A230, A232, A234). We demonstrate that only two enzymes can degrade most of these molecules at high concentrations (25 mM) in less than 5 minutes. Using surface assays adapted from NATO AEP-65 guidelines, we further show that enzyme-based solutions can decontaminate 97.6% and 99.4% of 10 g∙m−² of soman- and VX-contaminated surfaces, respectively. Finally, we demonstrate that these enzymes can degrade ethyl-paraoxon down to sub-inhibitory concentrations of acetylcholinesterase, confirming their efficacy from high to micromolar doses.