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Photocatalytic Oxidation of Sulfur Mustard and Its Simulant on BODIPY-Incorporated Polymer Coatings and Fabrics Hui Wang, George W. Wagner, Annie Xi Lu, Dominique L. Nguyen, James H Buchanan, Patrick M. McNutt, and Christopher J. Karwacki ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.8b04576 • Publication Date (Web): 16 May 2018 Downloaded from http://pubs.acs.org on May 16, 2018

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ACS Applied Materials & Interfaces

Photocatalytic Oxidation of Sulfur Mustard and Its Simulant on BODIPY-Incorporated Polymer Coatings and Fabrics Hui Wang,*,a George W. Wagner,a Annie Xi Lu,b Dominique L. Nguyen,c James H. Buchanan,a Patrick M. McNutt,c and Christopher J. Karwacki*,a a

U.S. Army Edgewood Chemical Biological Center, 8198 Blackhawk Road, Aberdeen Proving

Ground, MD 21010, United States b

Defense Threat Reduction Agency, 8228 Scully Road, Aberdeen Proving Ground, MD 21010,

United States c

Department of Neuroscience, U.S. Army Medical Research Institute of Chemical Defense,

2900 Ricketts Point Road, Aberdeen Proving Ground, MD 21010, United States KEYWORDS. chemical warfare agents, photooxidation, BODIPY photosensitizers, singlet oxygen, self-decontaminating materials

ABSTRACT. Sulfur mustard is one of the most toxic chemical warfare agents worldwide. We report the use of 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) photosensitizers as a fast and effective sulfur mustard decontaminant and their incorporation into various polymer coatings and fabrics, including army combat uniform. These BODIPY-embedded materials are capable of

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generating singlet oxygen under visible light irradiation and effectively detoxifying sulfur mustard by converting it into non-toxic sulfoxides as the major products. The rate of decontamination is found to be affected by the photosensitizer structure and concentration, as well as the excitation wavelength. The most effective BODIPY-embedded self-decontamination material observed in this study shows a half-life of only 0.8 min. In comparison to the current methods, which uses activated carbon as the adsorbent layer, these self-detoxifying coatings and fabrics provide constant destruction of and real-time protection against sulfur mustard.

INTRODUCTION Sulfur mustard, also known as mustard gas or HD, is a powerful vesicant chemical warfare agent that causes large blisters on the exposed skin, eyes and lung.1 Its first large-scale production and use as a chemical warfare agent (CWA) occurred during World War I when Germany unleashed HD on Allied troops near Ypres, Belgium in 1917.2 During this time, HD was considered the most toxic gas as it caused more casualties than other toxic gases combined.3 Despite its international ban and subsequent development of more toxic CWAs, including nerve agents, sulfur mustard continues to be a weapon of choice.4,5 The first decontaminants used for mustard gas were bleach powders of varying formulations.6 Even though bleach is quite effective in decontamination, it has many drawbacks: (1) fresh samples must be prepared due to loss of activity over time; (2) a large quantity of bleach is required for decontamination; and (3) bleach poses an environmental concern as it is corrosive. Since then, many materials have emerged in the search of new decontaminants for sulfur mustard, such as hydrogen peroxides,7–9 metal oxides,10–13 polyoxometalates,14–16 and metal organic frameworks (MOFs).17–20 Despite significant improvements, many of these materials or methods are limited to decontamination in


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solutions and cannot be directly applied on the battlefield for real-time protection. Detoxification of HD includes three major routes: hydrolysis,21,22 dehydrohalogenation,10,23 and oxidation.7,19,24–28 The hydrolysis pathway is limited by its slow kinetics and the poor solubility of mustard aqueous solutions. Dehydrohalogenation typically requires a high pH environment, which is corrosive to most materials, and thus it is not practical for real-time decontamination purposes. On the other hand, oxidation has proven to be a viable pathway for HD detoxification due to the presence of the oxidizable bivalent sulfur. Among the many oxidative routes investigated, singlet oxygen (1O2) has proven a prominent oxidant.19 1O2 is a reactive, short-lived species with a lifetime of microseconds in solution29 to milliseconds in air.30 The most common method of generating 1O2 is through energy transfer from the excited triplet state of a photosensitizer to the ground-state molecular oxygen (3O2).31,32 Photocatalysis driven by visible light is an environmentally benign and energy efficient strategy due to its ability to use sunlight as the energy source. Among the many organic photosensitizers that are capable of generating 1O2, 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) dyes exhibit many unique advantages. BODIPY dyes have excellent thermal and photochemical stabilities, high molar absorptivities in the visible light region,33 and readily tunable molecular structures,34 allowing their photophysical and electrochemical properties to be conveniently optimized. More importantly, properly designed BODIPY dyes exhibit long-lived triplet excited states and high 1O2 quantum yields, which have made them very useful in photodynamic therapy for combatting cancer cells.35 Despite their great

1

O2 generation

characteristics and promising results toward sulfide oxidation.36,37, BODIPY photosensitizers have not yet been widely applied for decontamination of HD.


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Recently, Farha et al. reported a BODIPY-functionalized zirconium-based MOF for detoxification of 2-chloroethyl ethyl sulfide (CEES), an HD simulant.20 Inspired by this work, herein, we report the photocatalytic decontamination of HD and CEES by three different BODIPY photosensitizers (Chart 1) under visible light and their retained catalytic activity in decontamination after incorporation into various polymer films and army combat uniform (ACU). A reaction mechanism is proposed to account for the differences between in-solution and solid-phase decontamination. Factors that affect the rate of decontamination by these BODIPYembedded materials are also presented.

Chart 1. Chemical structures of BODIPY photosensitizers used to decontaminate sulfur mustard.

EXPERIMENTAL SECTION BODIPY/PVDF Films. Polyvinylidene fluoride (PVDF) films doped with BODIPY photosensitizers were formed by solution casting. 1.0 g PVDF (Mw 534,000 g/mol) was mixed with 5.0 g DMF and heated at 50 oC for 2 h. The mixture was vortexed and reheated if necessary until the polymer was fully dissolved. To prepare 1 wt% BODIPY/PVDF films, 10 mg of BODIPY photosensitizer dissolved in 1.0 g DMF was added to the above solution and drop cast onto a Teflon plate. The solution was left to dry in a fume hood for approximately 5 h, then the film was carefully peeled off the Teflon plate and put in an oven (90 oC) to dry overnight. To prepare PVDF films containing different wt% of BODIPY, the concentration of photosensitizer


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added to the polymer solution was varied accordingly. BODIPY/PVDF Fibers. PVDF fibers containing BDP-H were prepared by electrospinning. Briefly, 1.0 g PVDF (Mw 534,000 g/mol) and 10 mg BDP-H were dissolved in 4 g DMF:acetone (4:1 w:w). The solution was added to a syringe with 22 gauge needle and dispensed from the syringe at a rate of 1 mL/h and a voltage of 12.5 kV. The rotating drum collector covered with aluminum foil was set at a rate of 300 rpm at distance of 10 cm from the tip of the needle. Electrospinning was performed at 35 oC. BODIPY-Coated ACUs. BODIPY-coated ACUs were prepared by a dip-coating method. Specifically, 3 mM solutions of each BODIPY photosensitizer (methanol for BDP-Ph, dichloromethane for BDP-I and distilled water for BDP-SO3) were prepared in 20-mL vials. ACUs were cut into small pieces and immersed in these solutions for 24 hours. BODIPY-coated ACUs were taken out of solution to dry under ambient temperature and then in an oven (50 0C) overnight. Note that photosensitizers adhered to ACUs quite strongly after they were prepared, provided that they were not washed with good solvents that would re-dissolve them. Surface Decontamination. Caution! Experiments involving HD should be run by trained personnel only using appropriate safety procedures. 2 µL HD or CEES was evenly applied on an ~ 1 x 1 cm piece of BODIPY-incorporated material in a 20 mL glass vial. The vial was sealed completely and irradiated with a light emitting diode (LED) for 60 min. After irradiation, 0.8 mL CDCl3 was added to the vial and the mixture was vortexed for 2 min to ensure efficient extraction of the products from the materials. The extracted solutions were then analyzed by both GC-MS and 1H NMR. For kinetics measurements, decontamination data was collected by running photooxidation reaction on each piece of BODIPY-incorporated materials for different


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time intervals. Singlet Oxygen Generation. In solution. In a UV-Vis quartz cuvette, a 2 mL solution containing 100 µM 1-naphthol and 1 µM BODIPY in methanol was irradiated with a blue LED through the clear side of the quartz cuvette. UV-Vis spectra were recorded at different time intervals to monitor the reduction of 1-naphthol caused by reacting with 1O2. On films. A piece of 1 wt% BDP-SO3/PVDF film (ca. 30 mg) was placed on the bottom of a UV-Vis quartz cuvette to ensure that the film did not interfere with UV-Vis spectra measurements. 2 mL of 100 µM 1-naphthol in isopropanol was added to the above cuvette and irradiated with a blue LED. Isopropanol was used instead of methanol due to insolubility of BDP-SO3 in isopropanol. This ensured that 1O2 measured did not come from photosensitizers that leached from BDP-SO3/PVDF film to the solution. UV-Vis spectra were recorded at different time intervals to monitor oxidation of 1-naphthol over time. RESULTS and DISCUSSION To show the viability of BODIPY as an HD decontaminant, a commercially available BODIPY photosensitizer, BDP-H, was chosen and tested for photooxidation of HD in solution. Briefly, a solution of BDP-H in methanol-d4 was sealed in a glass tube and purged with O2 for 20 min. HD was added to the solution. The reaction mixture was then irradiated with a 3W blue LED for 30 min and analyzed by both 1H and 13C NMR spectroscopy. As depicted in Figure 1a, 1

H NMR spectrum of HD contains two triplets at 3.7 and 2.9 ppm. After irradiation, these peaks

were completely gone and two multiplets appeared at 4.0, and 3.3 ppm (Figure 1b), which correspond to the chemical shifts of bis(2-chloroethyl) sulfoxide (HDO). Formation of this sole sulfoxide product was also confirmed by 13C NMR (Figure S4).


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Figure 1. 1H NMR spectra of a) pure HD in CD3OD, b) photooxidation product of HD (172 mM) catalyzed by BDP-H (1.5 mM) in CD3OD irradiated with a blue LED for 30 min under oxygen atmosphere, and c) photooxidation products of HD (2 µL) on a piece of BDP-H/PVDF film irradiated with a blue LED for 60 min under air atmosphere (products extracted with CDCl3). Note that the chemical shifts of alpha protons (a') of HDO in CDCl3 was slightly upfield with respect to those in CD3OD.

Next, we seek to evaluate the ability of BDP-H to decontaminate HD when it is incorporated in a polymer coating. For effective protection against CWAs, it is of great interests to develop coatings or protective clothing that are capable of self-detoxifying by incorporating reactive components into them.38–41 To this end, BDP-H was incorporated into polyvinylidene fluoride (PVDF) films which are themselves inert to photooxidation. To test the photooxidation activity, HD was evenly applied on a piece of BDP-H/PVDF film and irradiated by a blue LED for 60 min under air atmosphere. Similar to the solution phase decontamination, HD was completely removed after irradiation. However, in addition to the major HDO product, multiple other oxidation products, including bis(2-chloroethyl) sulfone (HDO2), 2-chloroethyl vinyl sulfoxide (CEVSO), and 2-chloroethyl vinyl sulfone (CEVSO2), also appeared (Scheme 1b). The triplet at 3.56 ppm indicates the formation of HDO2, while formation of the two vinyl oxidation products were clearly indicated by the chemical shifts of vinyl protons from 5.8 to 6.7 ppm (Figure 1c).


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The identities of each oxidation product were also confirmed by GC-MS (Figure S5). Note that despite sulfones are still vesicant, their concentrations were very low compared to the nonvesicant sufloxides.

Scheme 1. Decontamination of HD by BDP-H a) in solution and b) on a piece of BODIPY-embedded PVDF film.

Decontamination of CEES by BDP-H in solution and on films were also tested and gave similar results as HD decontamination, i.e. formation of only 2-chloroethyl ethyl sulfoxide (CEESO) in methanol and multiple oxidation products on films, including CEESO, 2-chloroethyl ethyl sulfone (CEESO2), ethyl vinyl sulfoxide (EVSO), and ethyl vinyl sulfone (EVSO2) (Scheme S1). This discrepancy between solution- and solid-phase decontamination can be explained by a solvent effect. It was previously reported that protic solvents can stabilize the reaction intermediate, persulfoxide, of sulfide oxidation by singlet oxygen through hydrogen bonding to give exclusively the sulfoxide product (Scheme S3).42,43 However, in the absence of a protic solvent, the non-hydrogen-bonded persulfoxide reacts with sulfoxides to form sulfones and sulfoxides. Furthermore, the formation of hydroperoxy sulfonium ylide intermediate is promoted, which causes the formation of vinyl oxidation products (Scheme 2).28,44 Indeed, when the photooxidation reaction was performed in an aprotic solvent, such as acetonitrile, the same oxidation products as those on the BDP-H-doped films were observed (Figure S3).


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Scheme 2. Proposed mechanism of HD oxidation by singlet oxygen on BODIPY-incorporated polymer coatings or fabrics.

To investigate the photooxidation kinetics, the catalytic activity of BDP-H was compared with two additional BODIPY photosensitizers. It is well known that attaching heavy atoms to photosensitizers increases 1O2 generation efficiency due to enhanced intersystem crossing, by which the triplet excited states of photosensitizers were produced.45 To test this, PVDF films doped with BDP-I photosensitizer, which has two iodine atoms attached to the core structure (Chart 1), were prepared. Due to the high risk of working with HD, only the photooxidation kinetics of CEES was measured. As expected, photooxidation of CEES on BDP-I/PVDF films was much faster than on BDP-H/PVDF films (Figure 2a). The calculated half-lives of BDPI/PVDF and BDP-H/PVDF films were 0.8 and 21 min, respectively. BDP-SO3 was chosen as a water-soluble counterpart of BDP-H. This was necessary for preparing polymer films that required water as the solvent (Table S1). BDP-SO3/PVDF films exhibited the slowest catalytic activity out of the three BODIPY photosensitizers tested and had a half-life of 46 min. Note that PVDF films alone displayed negligible catalytic activity under the same irradiation condition, indicating that BODIPY photosensitizers were solely responsible for the photocatalytic oxidation of CEES. Interestingly, the decontamination kinetics shown in Figure 2a doesn’t truly follow the trend of pseudo first order kinetics. We think these were probably caused by the rather large


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experimental errors as product conversions for each time point were collected on different pieces of BODIPY films or fibers (see Experimental Section). Figure 2b shows the photooxidation of CEES on a piece of BDP-SO3/PVDF film, subjected to four consecutive dosages of CEES. Near full conversions were observed for all four dosages, indicating the reusability of the film catalyst. In order to test their capability for decontamination on a more relevant material, BODIPY photosensitizers were incorporated into army combat uniforms (ACUs) which are composed of 50% nylon and 50% cotton. The successful incorporation of photosensitizers into ACUs were

Figure 2. a) Oxidation of CEES over time on different 1 wt% BODIPY/PVDF films (~ 18 mg) and 1 wt% BDPH/PVDF fibers (~ 18 mg) irradiated under blue LED and air atmosphere. b) Oxidation of CEES on a piece of 1 wt% BDP-SO3/PVDF film (~30 mg) irradiated under blue LED (60 min) and air atmosphere over four consecutive cycles. The film was washed with fresh CDCl3 and dried before next dosage.


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confirmed by confocal microscope images (Figure S10). Despite generally less efficient than BODIPY/PVDF films, BODIPY-coated ACUs were also capable of decontaminating CEES and their photooxidation kinetics showed a similar trend as those of BODIPY/PVDF films (Figure S7). To test the effect of morphology on decontamination, photosensitizers were also incorporated into electrospun PVDF fibers. We expected the larger surface area of electrospun fibers would result in a higher amount of 1O2 production and at the same time, allow more CWAs to get in close proximity to the photosensitizers, decreasing the typical distance 1O2 need to travel to reach the CWAs. To this end, PVDF fibers containing BDP-H, rather than the more reactive BDP-I, were prepared because we conceived that the moderate decontamination rate of BDP-H would be ideal for the proof of concept. As indicated in Figure 2a, electrospun fibers indeed performed better than its film counterpart. The calculated half-life of BDP-H/PVDF fibers was 16 min, 5

Figure 3. SEM images of 1 wt% BDP-H/PVDF a) film and b) fibers. Confocal microscope images (100× magnifications) of 1 wt% BDP-H/PVDF c) film and d) fibers.


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min faster than BDP-H/PVDF films. Despite different decontamination rates, the ratio of sulfoxide to other oxidation products was similar on both BDP-H films and fibers. Scanning electron microscopy (SEM) images of the electrospun fibers showed average size of ~ 1 µm (Figure 3b). Although visual inspection of both BDP-H/PVDF films and fibers showed uniform distrubtions of photosensitizers on the surface, images obtained using laser confocal microscopy showed aggregates of BDP-H on both films and fibers (Figure 3c & d). The larger aggregate sizes observed on films compared to fibers could also explain the lower decontamination efficiency of films as larger aggregates cause more self-quenching of photosensitizers. To further investigate the effect of photosensitizer aggregation on decontamination rate, PVDF films containing different amounts of BDP-H were prepared. As shown in Figure 4, at low BDPH concentration (between 0 and 0.1 wt%), the half-life of decontamination decreased with increasing photosensitizer concentration. On the other hand, at concentrations above 0.1 wt%, the half-life increased with increasing photosensitizer concentration. The fact that the films became less efficient in decontamination above 0.1 wt% BDP-H can be explained by addtional

Figure 4. Decontamination half-lives of CEES by PVDF films containing different concentrations of BDP-H.


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photosensitizers above this concentration threshold causing more aggregations of BDP-H on the films (Figure S11), which in turn caused lower amounts of 1O2 production . To study the effect of irradiation wavelength on the rate of CEES oxidation, we also conducted photooxidation of CEES on BDP-H/PVDF films using white and red LEDs. Blue LED has wavelengths between 450-495 nm, which overlap well with the absorption spectrum of BDP-H (Figure S8a). The wavelengths of red LED are 600-650 nm, which barely excites BDP-H. While the wavelengths of white LED span the whole visible spectrum, its blue light intensity is not as

Figure 5. a) Oxidation profile of CEES on BDP-H PVDF films irradiated with different LEDs under air atmosphere. b) Oxidation of 1-naphthol by BDP-SO3 PVDF film in the absence or presence of a 1O2 quencher, DABCO, under blue LED light and air atmosphere.


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strong as that of blue LED (Figure S12). As expected, blue LED was the most efficient for photooxidation of CEES. Under the same condition, white LED exhibited a slightly lower catalytic rate and the decontamination of CEES by red LED was neglegible (Figure 5a). It’s worth noting that same products were produced by all three LEDs despite their different photooxidation rates. 1-Naphthol was used to confirm the generation of 1O2 by BODIPY photosensitizers and determine its rate of production. 1-Naphthol is known to react with

1

O2 to produce

naphthoquinone (Scheme S2).46 This oxidation reaction can be monitored spectroscopically by observing the disappearance of absorbance of 1-naphthol at 296nm over time. We first measured the rates of 1O2 generation by the three BODIPY photosensitizers under homogeneous condition. BDP-I in methanol had the fastest rate of 1O2 production and BDP-SO3 had the slowest rate (Figure S8d), consistent with the decontamination results by BODIPY/PVDF films and BODIPY ACUs. To ensure that 1O2 generated does not come from photosensitizers leached from the films to the surrounding organic solvent, generation of 1O2 from BDP-SO3/PVDF films were measured in isopropanol. As shown in Figure 5b, oxidation of 1-naphthol in isopropanol in the presence of a BDP-SO3/PVDF film was much faster than that of a blank PVDF film. Moreover, the rate of 1

O2 generation by the BDP-SO3/PVDF film was hampered when exposed to DABCO which is a

known

1

O2 quencher,47 further confirming

the ability of generating 1O2 by BODIPY-

incorporated materials. CONCULSION In conclusion, we have demonstrated the use of BODIPY photosensitizers as an effective HD decontaminant and their incorporation into various polymer coatings or fabrics, such as PVDF


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films and the ACU. These materials are capable of generating 1O2 under visible light and effectively oxidizing HD and CEES into the non-toxic sulfoxides as the major products and sulfones as the minor products. In contrast, photooxidation of HD and CEES in methanol gives only the sulfoxide product. This discrepancy between solution- and solid-phase decontamination is caused by a solvent effect and reinforced the importance of collecting solid-phase decontamination results. Different decontamination kinetics by the three structurally similar BODIPY photosensitizers provide the opportunity to fine tune the decontamination rate by modifying the molecular structure of the photosensitizer. The rate of decontamination is also affected by the excitation wavelength and photosensitizer concentration. The most effective decontamination was observed with BDP-I/PVDF film with a half-life of only 0.8 min. Although already promising, the kinetics can be further improved by optimizing the BDP-I concentration loaded on the PVDF film. Overall, the developed materials and basic understanding of the design principles reported here will render great progress in development of reactive coatings or fabrics for CWA protection. ASSOCIATED CONTENT Supporting Information. The Supporting Information is available free of charge on the ACS Publications website: Materials and methods; NMR and GC-MS spectra; photooxidation studies on other BODIPYincorporated materials; singlet oxygen detection; oxidation mechanism of HD by 1O2; confocal microscope images (PDF) AUTHOR INFORMATION Corresponding Author


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*E-mail: [email protected] *E-mail: [email protected] Notes The authors declare no competing financial interest. ACKNOWLEDGMENTS The authors gratefully acknowledge Defense Threat Reduction Agency for funding this research under CB3934. This research was performed while H.W. held a National Research Council Research Associate Award and D.N. held an Oak Ridge Institute of Science and Engineering Fellowship Award. REFERENCES (1) Fitzgerald, G. J. Chemical Warfare and Medical Response During World War I. Am. J. Public Health 2008, 98, 611–625. (2) Ghabili, K.; Agutter, P. S.; Ghanei, M.; Ansarin, K.; Panahi, Y.; Shoja, M. M. Sulfur Mustard Toxicity: History, Chemistry, Pharmacokinetics, and Pharmacodynamics. Crit. Rev. Toxicol. 2011, 41, 384–403. (3) Geraci, M. J. Mustard Gas: Imminent Danger or Eminent Threat? Ann. Pharmacother. 2008, 42, 237–246. (4) Fassihi, F. U.N. Report Finds Chemical Weapons Used by Syrian Regime, Islamic State. The Wall Street Journal [Online], 2016. https://www.wsj.com/articles/u-n-report-finds-chemicalweapons-used-by-syrian-regime-islamic-state-1472092954


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(5) Khadder, K.; Elwazer, S.; Roberts, E.; Kourdi, E.; Qiblawi, T. Suspected Gas Attack in Syria Reportedly Kills Dozens. CNN [Online], 2017. http://www.cnn.com/2017/04/04/middleeast/idlib-syria-attack/index.html (6) Yang, Y.-C.; Baker, J. A.; Ward, J. R. Decontamination of Chemical Warfare Agents. Chem. Rev. 1992, 92, 1729–1743. (7) Wagner, G. W.; Yang, Y.-C. Rapid Nucleophilic/Oxidative Decontamination of Chemical Warfare Agents. Ind. Eng. Chem. Res. 2002, 41, 1925–1928. (8) Wagner, G. W.; Procell, L. R.; Sorrick, D. C.; Lawson, G. E.; Wells, C. M.; Reynolds, C. M.; Ringelberg, D. B.; Foley, K. L.; Lumetta, G. J.; Blanchard, D. L. All-Weather Hydrogen Peroxide-Based Decontamination of CBRN Contaminants. Ind. Eng. Chem. Res. 2010, 49, 3099−3105. (9) Picard, B.; Gouilleux, B.; Lebleu, T.; Maddaluno, J.; Chataigner, I.; Penhoat, M.; Felpin, F. X.; Giraudeau, P.; Legros, J. Oxidative Neutralization of Mustard-Gas Simulants in an OnBoard Flow Device with In-Line NMR Monitoring. Angew. Chem. Int. Ed. 2017, 56, 7568– 7572. (10) Wagner, G. W.; Koper, O. B.; Lucas, E.; Decker, S.; Klabunde, K. J. Reactions of VX, GD, and HD with Nanosize CaO: Autocatalytic Dehydrohalogenation of HD. J. Phys. Chem. B 2000, 104, 5118–5123. (11) Wagner, G. W.; Chen, Q.; Wu, Y. Reactions of VX, GD, and HD with Nanotubular Titania. J. Phys. Chem. C 2008, 112, 11901–11906.


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(12) Panayotov, D. A.; Paul, D. K.; Yates, J. T. Photocatalytic Oxidation of 2-Chloroethyl Ethyl Sulfide on TiO2−SiO2 Powders. J. Phys. Chem. B 2003, 107, 10571–10575. (13) Bandosz, T. J.; Laskoski, M.; Mahle, J.; Mogilevsky, G.; Peterson, G. W.; Rossin, J. A.; Wagner, G. W. Reactions of VX, GD, and HD with Zr(OH)4: Near Instantaneous Decontamination of VX. J. Phys. Chem. C 2012, 116, 11606–11614. (14) Gall, R. D.; Faraj, M.; Hill, C. L. Role of Water in Polyoxometalate-Catalyzed Oxidations in Nonaqueous Media. Scope, Kinetics, and Mechanism of Oxidation of Thioether Mustard (HD) Analogs by tert-Butyl Hydroperoxide Catalyzed by H5PV2Mo10O40. Inorg. Chem. 1994, 33, 5015–5021. (15) Okun, N. M.; Anderson, T. M.; Hill, C. L. Polyoxometalates on Cationic Silica: Highly Selective and Efficient O2/Air-Based Oxidation of 2-Chloroethyl Ethyl Sulfide at Ambient Temperature. J. Mol. Catal. A Chem. 2003, 197, 283–290. (16) Guo, W.; Lv, H.; Sullivan, K. P.; Gordon, W. O.; Balboa, A.; Wagner, G. W.; Musaev, D. G.; Bacsa, J.; Hill, C. L. Broad-Spectrum Liquid- and Gas-Phase Decontamination of Chemical Warfare Agents by One-Dimensional Heteropolyniobates. Angew. Chem. Int. Ed. 2016, 55, 7403–7407. (17) DeCoste, J. B.; Peterson, G. W. Metal–Organic Frameworks for Air Purification of Toxic Chemicals. Chem. Rev. 2014, 114, 5695−5727. (18) Liu, Y.; Howarth, A. J.; Vermeulen, N. A.; Moon, S.-Y.; Hupp, J. T.; Farha, O. K. Catalytic Degradation of Chemical Warfare Agents and Their Simulants by Metal-Organic Frameworks. Coord. Chem. Rev. 2016, 346, 101–111.


18

Page 19 of 23 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(19) Liu, Y.; Howarth, A. J.; Hupp, J. T.; Farha, O. K. Selective Photooxidation of a MustardGas Simulant Catalyzed by a Porphyrinic Metal-Organic Framework. Angew. Chem. Int. Ed. 2015, 54, 9001–9005. (20) Atilgan, A.; Islamoglu, T.; Howarth, A. J.; Hupp, J. T.; Farha, O. K. Detoxification of a Sulfur Mustard Simulant Using a BODIPY-Functionalized Zirconium-Based Metal–Organic Framework. ACS Appl. Mater. Interfaces 2017, 9, 24555–24560. (21) Wang, Q.-Q.; Begum, R. A.; Day, V. W.; Bowman-James, K. Sulfur, Oxygen, and Nitrogen Mustards: Stability and Reactivity. Org. Biomol. Chem. 2012, 10, 8786–8793. (22) Li, H.; Muir, R.; McFarlane, N.; Soilleux, R.; Yu, X.; Thompson, I.; Jackman, S. Soil Biotransformation of Thiodiglycol, the Hydrolysis Product of Mustard Gas: Understanding the Factors Governing Remediation of Mustard Gas Contaminated Soil. Biodegradation 2013, 24, 125–135. (23) Wagner, G. W.; Bartram, P. W.; Koper, O.; Klabunde, K. J. Reactions of VX, GD, and HD with Nanosize MgO. J. Phys. Chem. B 1999, 103, 3225–3228. (24) Richardson, D. E.; Yao, H.; Frank, K. M.; Bennett, D. A. Equilibria, Kinetics, and Mechanism in the Bicarbonate Activation of Hydrogen Peroxide: Oxidation of Sulfides by Peroxymonocarbonate. J. Am. Chem. Soc. 2000, 122, 1729–1739. (25) Boring, E.; Geletii, Y. V.; Hill, C. L. A Homogeneous Catalyst for Selective O2 Oxidation at Ambient Temperature. Diversity-Based Discovery and Mechanistic Investigation of Thioether Oxidation by the Au(III)Cl2NO3(thioether)/O2 System. J. Am. Chem. Soc. 2001, 123, 1625–1635.


19


Page 20 of 23

(26) Ringenbach, C. R.; Livingston, S. R.; Kumar, D.; Landry, C. C. Vanadium-Doped AcidPrepared Mesoporous Silica: Synthesis, Characterization, and Catalytic Studies on the Oxidation of a Mustard Gas Analogue. Chem. Mater. 2005, 17, 5580–5586. (27) Bromberg, L.; Pomerantz, N.; Schreuder-Gibson, H.; Hatton, T. A. Degradation of Chemical Threats by Brominated Polymer Networks. Ind. Eng. Chem. Res. 2014, 53, 18761– 18774. (28) Toutchkine, A.; Clennan, E. L. The Reactions of Singlet Oxygen with β-Chlorosulfides. The Role of Hydroperoxy Sulfonium Ylides in the Oxidative Destruction of Chemical Warfare Simulants. Tetrahedron Lett. 1999, 40, 6519–6522. (29) Adams, D. R.; Wilkinson, F. Lifetime of Singlet Oxygen in Liquid Solution. J. Chem. Soc., Faraday Trans. 2 1972, 68, 586–593. (30) Manceau, M.; Rivaton, A.; Gardette, J.-L. Involvement of Singlet Oxygen in the Solid-State Photochemistry of P3HT. Macromol. Rapid Commun. 2008, 29, 1823−1827 (31) DeRosa, M. C.; Crutchley, R. J. Photosensitized Singlet Oxygen and Its Applications. Coord. Chem. Rev. 2002, 233-234, 351–371. (32) Ghogare, A. A.; Greer, A. Using Singlet Oxygen to Synthesize Natural Products and Drugs. Chem. Rev. 2016, 116, 9994–10034. (33) Yogo, T.; Urano, Y.; Ishitsuka, Y.; Maniwa, F.; Nagano, T. Highly Efficient and Photostable Photosensitizer Based on BODIPY Chromophore. J. Am. Chem. Soc. 2005, 127, 12162–12163.


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Page 21 of 23 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(34) Loudet, A.; Burgess, K. BODIPY Dyes and Their Derivatives: Syntheses and Spectroscopic Properties. Chem. Rev. 2007, 107, 4891–4932. (35) Kamkaew, A.; Lim, S. H.; Lee, H. B.; Kiew, L. V.; Chung, L. Y.; Burgess, K. BODIPY Dyes in Photodynamic Therapy. Chem. Soc. Rev. 2013, 42, 77–88. (36) Li, W.; Xie, Z.; Jing, X. BODIPY Photocatalyzed Oxidation of Thioanisole under Visible Light. Catal. Commun. 2011, 16, 94–97. (37) Bandyopadhyay, S.; Anil, A. G.; James, A.; Patra, A. Multifunctional Porous Organic Polymers: Tuning of Porosity, CO2, and H2 Storage and Visible-Light-Driven Photocatalysis. ACS Appl. Mater. Interfaces 2016, 8, 27669–27678. (38) Grandcolas, M.; Louvet, A.; Keller, N.; Keller, V. Layer-by-Layer Deposited TitanateBased Nanotubes for Solar Photocatalytic Removal of Chemical Warfare Agents from Textiles. Angew. Chem. Int. Ed. 2009, 48, 161–164. (39) Wallace, R.; Giannakoudakis, D. A.; Florent, M.; Karwacki, C. J.; Bandosz, T. Ferrihydrite Deposited on Cotton Textiles as Protection Media Against the Chemical Warfare Agent Surrogate (2-Chloroethyl Ethyl Sulfide). J. Mater. Chem. A 2017, 5, 4972–4981. (40) Lu, A. X.; McEntee, M.; Browe, M. A.; Hall, M. G.; Decoste, J. B.; Peterson, G. W. MOFabric: Electrospun Nanofiber Mats from PVDF/UiO-66-NH2 for Chemical Protection and Decontamination. ACS Appl. Mater. Interfaces 2017, 9, 13632–13636. (41) Lee, D. T.; Zhao, J.; Peterson, G. W.; Parsons, G. N. Catalytic “MOF-Cloth” Formed via Directed Supramolecular Assembly of UiO-66-NH2 Crystals on Atomic Layer Deposition-


21


Page 22 of 23

Coated Textiles for Rapid Degradation of Chemical Warfare Agent Simulants. Chem. Mater. 2017, 29, 4894–4903. (42) Foote, C. S.; Peters, J. W. Chemistry of Singlet Oxygen. XIV. Reactive Intermediate in Sulfide Photooxidation. J. Am. Chem. Soc. 1971, 93, 3795–3796. (43) Liang, J. J.; Gu, C. L.; Kacher, M. L.; Foote, C. S. Chemistry of singlet oxygen. 45. Mechanism of the Photooxidation of Sulphides. J. Am. Chem. Soc. 1983, 105, 4717–4721. (44) Clennan, E. L. Persulfoxide: Key Intermediate in Reactions of Singlet Oxygen with Sulfides. Acc. Chem. Res. 2001, 34, 875–884. (45) Zhang, X. F.; Yang, X. Singlet Oxygen Generation and Triplet Excited-State Spectra of Brominated BODIPY. J. Phys. Chem. B 2013, 117, 5533–5539. (46) Madhavan, D.; Pitchumani, K. Photoreactions in Clay Media: Singlet Oxygen Oxidation of Electron-Rich Substrates Mediated by Clay-Bound Dyes. J. Photochem. Photobiol. A Chem. 2002, 153, 205–210. (47) Ouannes, C.; Wilson, T. Quenching of Singlet Oxygen by Tertiary Aliphatic Amines. Effect of DABCO (1,4-diazabicyclo[2.2.2]octane). J. Am. Chem. Soc. 1968, 90, 6527–6528.


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