Sulfur Mustard Simulant Research Articles

Efficient Catalytic Oxidative Desulfurization toward Thioether and Sulfur Mustard Stimulant by Polyoxomolybdate–Resorcin[4]arene-Based Metal–Organic Materials

The design and synthesis of effective and recyclable oxidative desulfurization catalysts is of great importance in view of environmental protection and human health. Herein, a family of polyoxomolybdate-based inorganic-organic hybrid materials, namely, [Mn(TMR4A)(H2O)4][Mo6O19]·0.5CH3CH2OH·H2O (1), [Ni(TMR4A)(H2O)4][Mo6O19]·0.5CH3CH2OH·H2O (2), [Zn(TMR4A)(H2O)4][Mo6O19]·0.5CH3CH2OH·H2O (3), and [Co2(TMR4A)2(H2O)4(β-Mo8O26)]·CH3CN·12H2O (4), were assembled by the functionalized resorcin[4]arene ligand (TMR4A) with polyoxomolybdate and metal ions under solvothermal conditions. In isostructural 1-3, the [M(TMR4A)(H2O)4]2+ species (M = MnII, NiII, ZnII) and [Mo6O19]2- anions are held together via C-H···O hydrogen bonds to give a 3D supramolecular architecture. In 4, two [Co(TMR4A)(H2O)2]2+ cations were linked by one [β-Mo8O26]4- anion to produce an attractive molecular dimer. Remarkably, 1-4, as recyclable heterogeneous catalysts, exhibit efficient catalytic oxidation desulfurization activities toward thioethers. Particularly, 1, as a representative example, features selective catalytic oxidation for sulfur mustard simulant. Moreover, their electrochemical properties were also studied.

Graphene Oxide-Based Membrane as a Protective Barrier against Toxic Vapors and Gases.

Traditional protective garments loaded with activated carbons to remove toxic gases are very bulky. Novel graphene oxide (GO) flake-based composite lamellar membrane structure is being developed as a potential component of a garment for protection against chemical warfare agents (CWAs) represented here by simulants, dimethyl methyl phosphonate (DMMP) (a sarin-simulant), and 2-chloroethyl ethyl sulfide (CEES) (a simulant for sulfur mustard), yet allowing a high-moisture transmission rate. GO flakes of dimensions 300-800 nm, 0.7-1.2 nm thickness and dispersed in an aqueous suspension were formed into a membrane by vacuum filtration on a porous poly(ether sulfone) (PES) or poly(ether ether ketone) (PEEK) support membrane for noncovalent π-π interactions with GO flakes. After physical compression of such a membrane, upright cup tests indicated that it can block toluene for 3-4 days and DMMP for 5 days while exhibiting excellent water vapor permeation. Further, they display very low permeances for small-molecule gases/vapors. The GO flakes underwent cross-linking later with ethylenediamine (EDA) introduced during the vacuum filtration followed by physical compression and heating. With a further spray coating of polyurethane (PU), these membranes could be bent without losing barrier properties vis-à-vis the CWA simulant DMMP for 5 days; a membrane not subjected to bending blocked DMMP for 15 days. For the PEEK-EDA-GO-PU-compressed membranes after bending, the separation factors of H2O over other species for low gas flow rates in the dynamic moisture permeation cell (DMPC) are: αH2O-He is 42.3; αH2O-N2 is 110; and αH2O-ethane is 1800. At higher gas flow rates in the DMPC, the moisture transmission rate goes up considerably due to reduced boundary layer resistances and exceeds the threshold water vapor flux of 2000 g/(m2·day) that defines a breathable fabric. This membrane displayed considerable resistance to permeation by CEES as well. The PES-EDA-GO-PU-compressed membrane shows good mechanical property under tensile strength tests.

Illuminating a Practical Solution to Clothing Protection from Mustard Gas

Lee et al. reported the first metal-organic framework (MOF)-fiber composite for the catalytic detoxification of a mustard gas simulant. The development of such wearable catalytic materials is an important step toward developing protection equipment that can simultaneously detoxify several chemical warfare agents (CWAs) under ambient conditions.

Highly efficient oxidation of various thioethers catalyzed by organic ligand-modified polyoxomolybdates

Herein, four hybrid dimers based on the carboxylic acid ligand-modified polyoxomolybdates were prepared, which could rapidly and selectively oxidize various phenyl sulfides and the sulfur mustard simulant 2-chloroethyl ethyl sulfide (CEES).

Self-assembly of polyoxovanadate-capped polyoxoniobates and their catalytic decontamination of sulfur mustard simulants.

We report the synthesis and characterization of two discrete vanadoniobates, H6Cs4Na5K7[V5Nb23O80]·28H2O (1) and H6Cs4Na5K8[V6Nb23O81]·34H2O (2), based on a brand new {Nb23} and a 5/6-nuclear polyoxovanadate cap. The two vanadoniobates as heterogeneous catalysts can effectively promote the oxidative decontamination of sulfur mustard simulants.

Protective Fabrics: Metal-Organic Framework Textiles for Rapid Photocatalytic Sulfur Mustard Simulant Detoxification

Summary Metal-organic frameworks (MOFs) can catalyze toxic chemical decontamination, but new MOF materials and synthesis strategies are needed to improve performance, particularly in field-usable MOF-textile formats. This article reports for the first time the exceptional photocatalytic reactivity of Al-PMOF (Al-porphyrin-based MOF), composed of an earth-abundant metal-containing Al(OH)O4 cluster bridged by H2TCPP (5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin) chromophores, against the toxic sulfur mustard simulant 2-chloroethyl ethyl sulfide (CEES) under visible-light irradiation. Furthermore, Al-PMOF is strongly immobilized into polymeric fibers via well-controlled Al2O3 solid film conversion using dimethylformamide/water cosolvent. The approach enables a secure integration of conformal Al-PMOF films onto polymer fibers at a relatively low synthesis temperature (120°C). In addition, on a per-unit mass of MOF basis, the surface-bound Al-PMOF films enable extremely rapid CEES detoxification turnover frequency, up to 170 mol CEES mol chromophore − 1 min − 1 , more than 10-fold faster than the best MOF powders and 2-fold better than MOF films reported to date.

Porphyrinic Silver Cluster Assembled Material for Simultaneous Capture and Photocatalysis of Mustard-Gas Simulant.

Silver cluster-assembled materials (SCAMs), by virtue of their tunable structure, accessible surface area and excellent stability, hold great promise as highly efficient catalysts. Herein, wereport a new SCAM [Ag12(StBu)6(CF3COO)3(TPyP)]n (denoted as Ag12TPyP) composed of a Ag12 chalcogenolate cluster core stabilized by porphyrinic ligands. Ag12TPyP showed superior sulfur mustard simulant (2-chloroethyl ethyl sulfide, CEES) degradation efficiency and achieved a half lifetime (t1/2) of 1.5 min with 100% selectivity. The experimental results demonstrated that synergistic effects between the silver cluster and photosensitizer ligand promote the efficiency of the generation of singlet oxygen (1O2), which accelerates the decontamination rate. Additionally, benefiting from strong affinity between the silver cluster and CEES, Ag12TPyP exhibits a CEES uptake of 74.2 mg g-1. This work demonstrates that SCAMs offer a new route to the rational design of novel materials for the detoxification of mustard gas.

Functionalized Textiles: Water-Stable Chemical-Protective Textiles via Euhedral Surface-Oriented 2D Cu-TCPP Metal-Organic Frameworks (Small 10/2019)

In article number 1805133, Gregory N. Parsons and co-workers effectively separate highly toxic chemicals including NH3 and 2-chloroethyl ethyl sulfide (CEES), a vesicant sulfur mustard simulant, through non-woven textiles functionalized with 2-D metal–organic frameworks (MOFs). The chemical protective membranes can potentially be applied to gas mask filters and to military garments to protect military populations from such hazards.

Sensitive Discrimination of Nerve Agent and Sulfur Mustard Simulants Using Fluorescent Coassembled Nanofibers with Förster Resonance Energy Transfer-Enhanced Photostability and Emission.

In this work, highly sensitive discrimination of nerve agent and sulfur mustard simulants is achieved by using photostable and fluorescent coassembled nanofibers from molecules 1 and 2. We demonstrate that the introduction of 2 as a Förster resonance energy transfer (FRET) acceptor not only enhances the photostability and emission efficiency compared to individual 1 nanofibers but also induces different binding interactions between analytes and 1-2 coassembled nanofibers and thereby distinct fluorescence quenching behaviors used for the discrimination of nerve agent and sulfur mustard simulants. Our findings represent an important advance toward sensitive detection and discrimination of chemical warfare agents (CWAs).

Mono-transition-metal-substituted polyoxometalate intercalated layered double hydroxides for the catalytic decontamination of sulfur mustard simulant.

The Keggin-type mono-transition-metal-substituted [PW11M(H2O)O39]5- (PW11M, M = Ni, Co, Cu) were intercalated into Zn2Cr-based layered double hydroxide (Zn2Cr-LDH) by an exfoliation-reassembly method and the synthesized Zn2Cr-LDH-PW11M composites were thoroughly characterized by Fourier transform infrared (FT-IR) spectroscopy, powder X-ray diffraction (PXRD), solid state 31P nuclear magnetic resonance (31P NMR) spectroscopy, thermogravimetric analysis (TGA), inductively coupled plasma atomic emission spectroscopy (ICP-AES), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The three composites can be used as heterogeneous catalysts to promote the oxidative decontamination of the sulfur mustard simulant 2-chloroethyl ethyl sulfide (CEES). Interestingly, a cooperative effect between the PW11M cluster and Zn2Cr-LDH is evidenced by the fact that the composites have a higher catalytic performance than either of the individual constituents alone. The catalytic activity of Zn2Cr-LDH-PW11M is significantly influenced by the substituted transition metals, showing the order: Zn2Cr-LDH-PW11Ni > Zn2Cr-LDH-PW11Co > Zn2Cr-LDH-PW11Cu. Under ambient conditions, the Zn2Cr-LDH-PW11Ni composite can convert 98% of CEES in 3 h using nearly stoichiometric 3% aqueous H2O2 with the selectivity of 94% for the nontoxic product 2-chloroethyl ethyl sulfoxide (CEESO). Moreover, the decontaminating material, Zn2Cr-LDH-PW11Ni, is stable to leaching and can be readily reused for up to ten cycles without obvious loss of its activity.

A Versatile Self-Detoxifying Material Based on Immobilized Polyoxoniobate for Decontamination of Chemical Warfare Agent Simulants.

A decontaminating composite, Mg3 Al-LDH-Nb6 , has been successfully prepared by immobilizing Lindqvist [H3 Nb6 O19 ]5- (Nb6 ) into a Mg3 Al-based layered double hydroxide (Mg3 Al-LDH). To our knowledge, this represents the first successful approach to the immobilization of polyoxoniobate. As a versatile catalyst, Mg3 Al-LDH-Nb6 can effectively catalyze the degradation of both vesicant and nerve agent simulants by multiple pathways under mild conditions. Specifically, the sulfur mustard simulant, 2-chloroethyl ethyl sulfide (CEES), is converted into the corresponding nontoxic 2-chloroethyl ethyl sulfoxide (CEESO) by selective oxidation, whereas the Tabun (G-type nerve agent) simulant, diethyl cyanophosphonate (DECP), and the VX (V-type nerve agent) simulant, O,S-diethyl methylphosphonothioate (OSDEMP), are detoxified through hydrolysis and perhydrolysis, respectively. A possible mechanism is proposed on the basis of control experiments and spectroscopic studies. The Mg3 Al-LDH-Nb6 composite exhibits remarkable robustness and can be readily reused for up to ten cycles with negligible loss of its catalytic activity. More importantly, a protective "self-detoxifying" material has easily been constructed by integrating Mg3 Al-LDH-Nb6 into textiles. In this way, the flexible and permeable properties of textiles have been combined with the catalytic activity of polyoxoniobate to remove 94 % of CEES in 1 h by using nearly stoichiometric dilute H2 O2 (3 %) as oxidant with 96 % selectivity.

Mechanistic reaction model for oxidation of sulfur mustard simulant by a catalytic system of nitrate and tribromide.

A new metal-free catalytic reaction system is developed to selectively oxidize 2-chloroethyl ethyl sulfide (CEES), a surrogate of sulfur mustard. The combination of two catalytic precursors, tribromide and nitrate, allows a rapid sulfoxidation of CEES even at ambient conditions. The kinetic behaviours at various reaction conditions are investigated to identify the most probable reaction pathways of the development of catalytic loop and the overall reaction steps of CEES sulfoxidation. The mechanistic study demonstrates that the catalytic loop does not require an addition of mineral acid or water, which is common in most other reaction systems. Incomplete catalytic systems with one precursor are also examined to uncover the complex network of sulfoxidation in the catalytic reaction system. The results reveal that the complex between CEES and bromine is a reactive intermediate, bromosulfonium, which can be further catalysed and converted into sulfoxide by nitrate. Based on the proposed reaction mechanism, a predictive kinetic model fully describing most reaction behaviours is developed.

Preparation, characterization and evaluation of the zinc titanate and silver nitrate incorporated wipes for topical chemical and biological decontamination

Chemical and biological warfare agents have detrimental effects on biological systems. These agents are rapidly absorbed through skin and hence warrant immediate decontamination. Zinc titanate (ZnTiO3), is a well-proven moiety used for neutralizing chemical warfare agents (CWA) and silver is widely used as an antibacterial agent. Spacer fabric sheet, due to its ability to hold large amount of agents, was hydrothermally treated with silver nitrate (AgNO3) and incorporated with nano ZnTiO3 to prepare decontamination (deconwipes). Prepared deconwipe was characterized using X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). Uniform deposition of nano ZnTiO3 and AgNO3 in the wipe was demonstrated by SEM and XRD. In-vivo dermal decontamination efficacy of the prepared deconwipe was evaluated against nerve agent simulant (diethylchlorophosphate; DCP) and sulfur mustard simulant (2‑chloroethyl ethyl sulfide; CEES) on rat model using SEM, Flow Cytometry, Comet Acetylcholinesterase (AChE) inhibition assay and Organ Histopathology. In-vitro antibacterial and antifungal efficacy of the prepared deconwipe was evaluated using growth inhibitory efficacy techniques followed by SEM analysis. SEM and histopathology at dermal level revealed the decontamination efficacy of the prepared deconwipe. Nearly 90% decrease in AChE inhibition was observed in decontaminated rat in place of rate model as compared to the DCP contaminated rats. No significant attenuation was observed in DCP and CEES-induced cell cycle distribution and DNA damage analysis in decontaminated group. Furthermore, >95% inhibition of bacterial and fungal growth, proved its antibacterial and antifungal activity respectively. Thus, prepared deconwipes exhibit promising skin decontamination property against Chemical and biological contaminants.

Benzothiazole modified rhodol as chemodosimeter for the detection of sulfur mustard simulant

In this paper, we introduced a new sensor for detecting sulfur mustard (SM) and its simulant through the functionalization of a rhodol chromophore with benzothiazole, followed by thionation of the spirolactam. The synthesized chemodosimeter (RHBT) exhibited an obvious green-yellow fluorescence enhancement and chromogenic change from colorless to fuchsia in the presence of SM and its simulant stimuli, which is based on the spirothiolactam ring opening of rhodol induced by the synergy of S-alkylation of thiolactam and the excited state intramolecular proton transfer (ESIPT) of rhodol–benzothiazole. Furthermore, the chemodosimeter was successfully demonstrated for the rapid detection of SM and its simulant in solution, soil and air at ambient temperature, indicating its potential application for on-site detection of sulfur mustard.

Highly Efficient and Selective Photooxidation of Sulfur Mustard Simulant by a Triazolobenzothiadiazole-Moiety-Functionalized Metal-Organic Framework in Air.

A photoactive triazolobenzothiadiazole (TBTD)-conjugated terphenyldicarboxylate (TPDC) linker was introduced into a porous and robust UiO-68 isoreticular zirconium metal-organic framework (denoted as UiO-68-TBTD) by the de novo synthetic approach of mixed TPDC struts. Under blue-light-emitting-diode irradiation, UiO-68-TBTD can serve as a heterogeneous photocatalyst for the highly efficient and selective oxidation of a sulfur mustard simulant (2-chloroethyl ethyl sulfide) to the corresponding much less toxic sulfoxide product, with a half-life of only 3 min in the open air atmosphere.

A Turn-On Fluorescent Probe for Detection of Sub-ppm Levels of a Sulfur Mustard Simulant with High Selectivity

A new type of fluorescent probe capable of detecting a sulfur mustard (SM) simultant at a concentration of 1.2 μM in solution and 0.5 ppm in the gas phase has been developed. Owing to its molecular structure with a thiocarbonyl component and two piperidyl moieties integrated into the xanthene molecular skeleton, this probe underwent a highly selective nucleophilic reaction with the SM simultant and generated a thiopyronin derivative emitting intensive pink fluorescence. The distinct difference in electronic structure between the probe and thiopyronin derivative generated a marked shift of the absorption band from 445 to 567 nm, which enabled an optimal wavelength propitious for exciting the thiopyronin derivative but adverse to the probe. Such efficient separation of the excitation wavelength and tremendous increase in fluorescence quantum yield, from less than 0.002 to 0.53, upon conversion from the probe to the thiopyronin derivative, jointly led to a distinct contrast in the beaconing fluorescence signal (up to 850-fold) and therefore the unprecedented sensitivity for detecting SM species.

Recoverable amphiphilic polyoxoniobates catalyzing oxidative and hydrolytic decontamination of chemical warfare agent simulants in emulsion

Amphiphilic polyoxoniobates (PONbs), [CnH2n+1N(CH3)3]7HNb6O19 (for 1, n=14; for 2, n=16; and for 3, n=18), were successfully prepared by the electrostatic interaction of hexaniobate anions with quaternary ammoniums containing long alkyl chain, and thoroughly characterized by using various techniques including Fourier transform infrared (FT-IR), 1H nuclear magnetic resonance (1H NMR), 13C nuclear magnetic resonance (13C NMR), thermogravimetric analysis (TGA), and elemental analysis. All three PONbs were used in the emulsion systems to catalytically decontaminate chemical warfare agent simulants and the influences of quaternary ammonium cations, polyanions, and amount of catalyst on the catalytic efficiency have been evaluated. Under optimal conditions, catalyst 3 in emulsion can completely convert both a the nerve agent simulant, diethyl cyanophosphonate (DECP), in 2h by hydrolysis and a sulfur mustard simulant, 2-chloroethyl ethyl sulfide (CEES), in 20min by oxidation using nearly stoichiometric 3% aqueous H2O2. Moreover, the amphiphilic catalyst 3 can be simply separated and readily reused for five recycles without obvious losing its activity. To the best of our knowledge, this study represents the first example where the emulsions of PONbs are used in the catalysis.

Detoxification of a Sulfur Mustard Simulant Using a BODIPY-Functionalized Zirconium-Based Metal-Organic Framework.

Effective detoxification of chemical warfare agents is a global necessity. As a powerful photosensitizer, a halogenated BODIPY ligand is postsynthetically appended to the Zr6 nodes of the metal-organic framework (MOF), NU-1000, to enhance singlet oxygen generation from the MOF. The BODIPY/MOF material is then used as a heterogeneous photocatalyst to produce singlet oxygen under green LED irradiation. The singlet oxygen selectively detoxifies the sulfur mustard simulant, 2-chloroethyl ethyl sulfide (CEES), to the less toxic sulfoxide derivative (2-chloroethyl ethyl sulfoxide, CEESO) with a half-life of approximately 2 min.

Decontamination and Remediation of the Sulfur Mustard Simulant CEES with "Off-the-Shelf" Reagents in Solution and Gel States: A Proof-of-Concept Study.

The decontamination and remediation of sulfur mustard chemical warfare agents remains an ongoing challenge. Herein, we report the use of “off‐the‐shelf” metal salts alongside commercially available peroxides to catalyze the degradation of the simulant 2‐chloroethyl ethyl sulfide (CEES) in solution and encapsulated within a supramolecular gel.

Controllable Synthesis of Lindqvist Alkoxopolyoxovanadate Clusters as Heterogeneous Catalysts for Sulfoxidation of Sulfides.

Six alkoxohexavanadate-based Cu- or Co-POVs [Cu(dpa)(acac)(H2O)]2[V6O13(OMe)6] (1), [Cu(phen)(acac)(MeOH)]2[V6O13(OMe)6] (2), [Co(dpa)(acac)2]2[V6O13(OMe)6]·2MeOH (3), [Co(phen)(acac)2]2[V6O13(OMe)6] (4), [Cu(dpa)(acac)]2[VIV2VV4O12(OMe)7] (5), and [Cu(dpa)(acac)(MeOH)]2[VIV2VV4O11(OMe)8] (6) (POV = polyoxovanadate; dpa = 2,2'-dipyridine amine; phen = 1,10-phenanthroline; acac = acetylacetone anion) have been synthesized by controlling the reaction conditions and characterized by single-crystal X-ray diffraction and powder X-ray diffraction analyses, FT-IR spectroscopy, element analyses, and X-ray photoelectron spectroscopy. In compounds 1-4 and 6, Cu or Co complexes and alkoxohexavanadate anions are assembled through electrostatic interactions. Differently, in compound 5, seven-methoxo-substituted Lindqvist-type [V6O12(OMe)7]2- are bridged to Cu complex via terminal O atoms by coordination bonds. All compounds 1-6 exhibit excellent heterogeneous catalytic performance in oxidative desulfurization and CEES ((2-chloroethyl) ethyl sulfide, a sulfur mustard simulant) abatement with H2O2 as oxidant. Among them, the catalytic activity of 6 [conv. of DBT (dibenzothiophene) up to 100% in 6 h; conv. of CEES reached 100% and selectivity of CEESO ((2-chloroethyl) ethyl sulfoxide) up to 85% after 4 h] outperforms others and can be reused without losing its activity.