Simple and Compelling Biomimetic Metal–Organic Framework Catalyst for the Degradation of Nerve Agent Simulants

Abstract

Inspired by biology, in which a bimetallic hydroxide-bridged zinc(II)-containing enzyme is utilized to catalytically hydrolyze phosphate ester bonds, the utility of a zirconium(IV)-cluster-containing metal-organic framework as a catalyst for the methanolysis and hydrolysis of phosphate-based nerve agent simulants was examined. The combination of the strong Lewis-acidic Zr(IV) and bridging hydroxide anions led to ultrafast half-lives for these solvolysis reactions. This is especially remarkable considering that the actual catalyst loading was a mere 0.045 % as a result of the surface-only catalysis observed.

Instantaneous Hydrolysis of Nerve‐Agent Simulants with a Six‐Connected Zirconium‐Based Metal–Organic Framework

“…Notably,Z r IV is strongly acidic-an attractive feature for activation of coordinated phosphate species.F inally,t he nodes of these MOFs which contain zirconium-bridging hydroxo ligands resemble the Zn-OH-Zn active sites of phosphotriesterase enzymes. [9] We have previously demonstrated that UiO-66 (12-connected), an ominally 12-connected Zr 6 -based MOF,c an hydrolyze the nerve-agent simulant dimethyl 4-nitrophenyl phosphate (DMNP) with a t 1/2 of 50 min at room temperature (Table 1illustrates the idealized (i.e., defect-free) structure of UiO-66 (12-connected) and associated Zr 6 node). [9] DMNP, apesticide containing aphosphate ester bond, is widely used as anerve-agent simulant owing to its structural similarity to G-series nerve agents,b ut with the advantage of notably lower toxicity.I nafollow up study,w ei ntroduced, proximal to the Zr 6 node,l inker-pendant amines having sufficient basicity to facilitate hydrolysis-related proton-transfer reactions and/or generate hydrolysis-relevant aqueous hydroxide.…”

“…Figure 2s hows the hydrolysis reaction of nerve-agent simulant DMNP in aqueous buffer solution with MOF-808 (6-connected) as the catalyst. Our previous approach to mon- UiO-66 (12-connected) [9] 1.5 35 0.004…”

An Overview of Detection and Neutralization of Chemical Warfare Agents Using Metal Organic Frameworks

“…This principle can be exploited for sensing the nitro aromatics and DMNB (dimethyl dinitrobutane) taggant for the plastic explosives. Lan et al demonstrated the highly luminescent MOF, [Zn 2 (bpdc) 2 -(bpee)] for the detection of trace explosives in the vapour phase with 84% fluorescence quench efficiency [38] . They reported vapour phase trace amounts of DMNB at 2.7ppm and Dinitro toluene (DNT) at 0.18 ppm detected within 10sec.…”

“…Naturally occurring phosphotriestrate (PTE) enzyme found in Pseudomonas diminuta, Flavobacterium, Agrobacterium radiobacter, and Chryseobacterium balustinum bacteria, known to be highly active in hydrolysis of phosphate ester bonds [40]. The Zn (II) metal ions in the enzyme cleave the P-O bonds.…”

Perspective: Metal-organic frameworks—Opportunities and challenges

“…The juxtaposition of different chemistries allows exciting new reactivity, e.g., in nerve agent hydrolytic degradation under mild conditions. 29 One area where the combination of new structure types and increasing ability to post-synthetically functionalise the materials could pay off is in photocatalytic transformations, 30 where porphyrins used in the natural photosystems have been arranged to generate hydrogen with visible light from water, 31 and the combination of solar absorbers with efficient electron transfer catalysts has been demonstrated. 32 Porphyrin-based systems also show promise in tuneable biomimetic oxidation catalysis.…”