Degradation and Detection of the Nerve Agent VX by a Chromophore-Functionalized Zirconium MOF

Abstract

Nerve agents are among the most toxic substances known to man. Recent events in Syria, Malaysia, and the UK illustrate that the threat of these substances is real and actual. The timely detection and identification of nerve agents is of great importance to facilitate timely decontamination or medical countermeasures. In this work, an effective and sensitive detection system, based on the metal−organic framework (MOF) NU-1000, was developed for the disclosure of V-agents, a class of nerve agents that is very persistent, highly toxic, and difficult to detect. NU-1000 is a zirconium-based MOF that can hydrolyze VX into a nontoxic phosphonic acid and the thiol 2-(diisopropylamino)ethanethiol. In this work, it was hypothesized that the four noncoordinating sites that are present on each Zr-building brick of this MOF could be functionalized with the two carboxylates present in 5,5′-di-thio-bis(2-nitrobenzoic acid), DTNB. This dimeric (RS-SR) compound efficiently reacts with thiols by S−S bond exchange and results in the release of the chromophore RS-H. Thus, the target hybrid material (DTNB@ NU-1000) was expected to degrade VX and at the same time give a visual color response upon reaction of the thiol-containing degradation product of VX with MOF-bound DTNB. We here report that DTNB@NU-1000 can be readily synthesized and that it is surprisingly active in the degradation of VX in neutral buffer. Moreover, the degradation of VX resulted in a color response, the intensity of which showed linear correlation with the VX concentration used. The applicability of this material was illustrated by a proof-of-concept detection kit for VX-contaminated surfaces, as exemplified with VX-contaminated metal panels coated with military paint [chemical agent resistant coating]. This procedure requires minimal training burden, and VX contamination down to a level of about 1−2 μg/cm 2 could be reliably visually established, during a total handling time of 20 min.

Pyrene-based metal organic frameworks: from synthesis to applications

“…In the case of NU-1000, SALI approach takes advantage of the ability of the Zr 6 nodes to be altered through the reaction between the free Zr-OH moieties (labile -OH and H 2 O ligands) and introduced nonstructural organic ligands. 90 The functional ligands may be carboxylic acid containing molecules, [265][266][267][268][269] phosphonic acid containing molecules, 270 or perfluoroalkane chains, 271 in which their addition in NU-1000 results in enhanced activity in different catalytic reactions. Moreover, the further modification of the ligands with varying electron-donating or electron-withdrawing groups can be performed to tune the electronic environment provided by the Zr 6 nodes.…”

“…Moreover, the further modification of the ligands with varying electron-donating or electron-withdrawing groups can be performed to tune the electronic environment provided by the Zr 6 nodes. 267 SALI-modification of NU-1000 can be performed with an organic ligand, 268 or a metal complex featuring an organic ligand. 269 NU-1000 functionalized by 5,5di-thio-bis(2-nitrobenzoic acid) ligand (DTNB@NU-1000) was found to be catalytically active for the degradation and subsequent detection of a nerve agent, which was observed by the release of the chromophore degradation product by visual inspection of filtered samples.…”

“…269 NU-1000 functionalized by 5,5di-thio-bis(2-nitrobenzoic acid) ligand (DTNB@NU-1000) was found to be catalytically active for the degradation and subsequent detection of a nerve agent, which was observed by the release of the chromophore degradation product by visual inspection of filtered samples. 268 The immobilization of an Ir(III) complex with a bis-phosphinite pincer ligand in NU-1000 was performed to enhance the catalytic activity toward the hydrogenation of liquid alkenes (1-decene and styrene) compared to that of homogeneous Ir(III)-complex, by preventing leaching of Ir from the structure. 269 SALI-based ligand incorporation can be followed by anchoring catalytically active metal sites on the ligand attached to the Zr nodes.…”

A computational study of water in UiO‐66 Zr‐MOFs: Diffusion, hydrogen bonding network, and confinement effect

“…7,8 Metal organic frameworks (MOFs) are a novel class of materials, formed by inorganic cores connected by organic linkers to extended networks with high porosities and ultrahigh surface areas. 9 MOFs can therefore provide adsorption properties competitive with commercially available adsorbents and have found application in the catalytic decontamination of toxic chemicals. 10 Several Zr-MOFs were shown to be promising catalysts for CWAs hydrolysis due to their stability in water and at high temperatures, 11 and the presence of hydroxyl groups bridging Zr atoms.…”

“…Metal organic frameworks (MOFs) are a novel class of materials, formed by inorganic cores connected by organic linkers to extended networks with high porosities and ultrahigh surface areas 9 . MOFs can therefore provide adsorption properties competitive with commercially available adsorbents and have found application in the catalytic decontamination of toxic chemicals 10 .…”