Probing the role of PO stretching mode enhancement in nerve-agent sensors: Simulation of the adsorption of diisopropylfluorophosphate on the model MgO and CaO surfaces

Kołodziejczyk, Wojciech; Majumdar, D.; Roszak, Szczepan; Leszczyński, Jerzy

doi:10.1016/j.cplett.2007.11.006

Cited by 14 publications

(9 citation statements)

References 22 publications

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“…Using the B3LYP hybrid functional, he studied interactions with DMMP, sarin, and trichlorophosphate and found that the most energetically favorable adsorption complex binds through the oxygen of the PO bond to the silanol site. Kolodziejczyk et al 4 examined DFP adsorption on CaO and MgO surfaces using a cluster approach within DFT. Using temperature-programmed desorption, Henderson et al 5 measured an activation barrier for the desorption of DMMP from silica of ∼16.9 kcal/mol.…”

Section: ■ Introductionmentioning

confidence: 99%

Surface Binding of Organophosphates on Silica: Comparing Experiment and Theory

Taylor

Runge²,

Cory

et al. 2013

J. Phys. Chem. C

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A consistent embedding hierarchy is applied to the calculation of binding enthalpies for organophosphate molecules to a silica surface and compared to experiment. The interaction of four probe molecules, dimethyl methylphosphonate (DMMP), diisopropyl methylphosphonate (DIMP), diisopropyl fluorophosphate (DFP), and sarin, with the silica surface is examined. Quantum chemical methods are employed to compute binding enthalpies and vibrational spectra for all interactions between probe molecules and silanol sites on the silica surface. Comparison with experimentally measured infrared shifts indicates that the theoretically modeled adsorption sites are similar to those found in experiment. The calculated binding enthalpies agree well with experiment for sarin, ΔH ads,443K = −22.0 kcal/mol (calculated) vs −18.8 ± 5.5 kcal/mol (measured, 433 K < T expt < 453 K), and DIMP, ΔH ads,463K = −26.9 kcal/mol (calculated) vs −29.3 ± 0.9 kcal/mol (measured, 453 K < T expt < 473 K). Agreement with experiment is less good for DMMP, ΔH ads,463K = −19.7 kcal/mol (calculated) vs −26.1 ± 1.5 kcal/mol (measured, 453 K < T expt < 473 K), and DFP, ΔH ads,423K = −20.4 kcal/mol (calculated) vs −27.5 ± 3.1 kcal/mol (measured, 413 K < T expt < 433 K).

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Section: ■ Introductionmentioning

confidence: 99%

Surface Binding of Organophosphates on Silica: Comparing Experiment and Theory

Taylor

Runge²,

Cory

et al. 2013

J. Phys. Chem. C

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“…There are theoretical studies of dickite using the ONIOM method, of tetrahedral edge clay mineral fragments by MP2, of CaO and (ZnO) n clusters using DFT and MP2 methods, and of γ-Al 2 O 3 clusters by DFT calculations . In these works, desorption occurs as a result of the coordination of the PO bond to the acidic surface sites. , Because the reactant is bonded to the surface, it can react, an essential feature of the catalytic properties of soils . Consequently, the relevant neurotoxic bond can be broken.…”

Section: Introductionmentioning

confidence: 99%

“…MgO can destroy phosphorus compounds, and it has been successfully used as a destructive adsorbent for toxic agents in experiments employing dimethyl methylphosphonate (DMMP), ,, VX, and mustard gas compounds. , In particular, Li et al showed experimentally that the addition of water to a phosphorus compound dramatically enhances the facility of MgO to destroy it. There have been also theoretical works using MP2 and representative cluster models to calculate the electronic structure of these systems. , …”

Section: Introductionmentioning

confidence: 99%

Hydrolysis of a VX-like Organophosphorus Compound through Dissociative Chemisorption on the MgO(001) Surface

et al. 2013

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Organophosporous VX agent O-ethyl S-(2-diisopropylethylamino)ethyl methylphosphonothioate is one of the main nerve agents. For this reason, the search for ways to deactivate it is very important. In this work, hydrolysis and adsorption reactions of a VX-like compound (O,S-dimethyl methylphosphonothioate, DMPT) on the MgO(001) surface were studied by density-functional theory (DFT) using periodic boundary conditions. A degradation reaction mechanism was proposed and theoretically investigated on two types of MgO(001) surfaces: the terrace and the Al-doped. Conformations, free-energy differences, transition states, reaction barriers, and minimum-energy paths were computed. We found that the P–S bond, related to the agent toxicity, breaks via hydrolysis occurring spontaneously throughout the analyzed temperature range, 100–600 K. In the dissociative chemisorption of the DMPT molecule, the formation of the MgO:[PO(CH3)(OCH3)]+[SCH3]− intermediate is catalytically favored from a temperature of about 335 K for the Al-doped surface, a value considerable smaller than the 500 K value for the same process on the terrace. At 335 K, the dissociation fragments on the Al-doped surface are less stable in comparison to the hydrolysis products. The possible reconstitution of the P–S bond on both surfaces does not occur according to kinetic analysis; however, the electronic energy barrier for the direct dissociation reaction on the Al-doped sites is about 49.0 kJ/mol lower than the value for the terrace. After recombination with the OH– and H+ ions, the HOPO(CH3)(OCH3) and HSCH3 products do not accumulate on either surface because these molecules desorb below the DMPT dissociation temperatures. The Al-doped sites of MgO(001) are thus more active in the catalytic hydrolysis process of the VX-like organophosphorus compound than is the nondoped surface.

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“…These highly toxic organophosphate compounds have a history of usage in chemical warfare because of their fatal interruption of acetylcholinesterase (AchE) activity in living organisms. Several fluorescence-based techniques are available at present to detect NAs, , but except for a few cases, , not much effort has been made to take advantage of Raman spectroscopy-based techniques to detect these toxic materials.…”

Section: Introductionmentioning

confidence: 99%

“…The motivation is that the experimentalists may use the theoretical results with respect to this molecule directly, as it lacks the proper efficiency of a NA. Our earlier theoretical studies on the interaction of DFP with small CaO and MgO clusters have revealed that they could be physisorbed on these oxides through interactions with the oxygen of their -PO group and the Raman intensity of the PO stretching mode (RI PO ) shows enhancement with respect to the isolated DFP. This is the real impetus behind our present study.…”

Section: Introductionmentioning

confidence: 99%

Density Functional Theory Based Studies on the Nature of Raman and Resonance Raman Scattering of Nerve Agent Bound to Gold and Oxide-Supported Gold Clusters: A Plausible Way of Detection

2010

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A detailed theoretical investigation has been carried out at the density functional level of theories to investigate the nature of Raman intensities of the -P=O stretching mode of a model nerve agent DFP (diisopropylfluorophosphate) when bound to different gold (Au(8), Au(20)) and oxide-supported gold (MgO...Au(4), CaO...Au(4), TiO(2)...Au(4), Al(2)O(3)...Au(4), M(16)O(16)...Au(8), and [M(16)O(15)...Au(8)](2+), M = Ca, Mg) clusters. All of these clusters and the DFP-bound clusters are fully optimized, and the computed energetics shows that DFP attaches itself weakly to these clusters. The normal Raman spectra calculations on these clusters show that there is substantial enhancement of the -P=O stretching mode of DFP compared to the isolated species. This enhancement has been found to be due to the polarization of the -P=O bond of DFP when bound to the clusters. Significant enhancement in intensity has been observed in the case of Au(n)...DFP (n = 8, 20), M(16)O(16)...Au(8)...DFP, and [M(16)O(15)...Au(8)](2+)...DFP (M = Ca, Mg) clusters. The resonance Raman calculations on the Au(n)...DFP (n = 8, 20) reveals that this enhancement could be made quite large and selective, which is a feature that is unique to the nerve agents and could be used as a property for detecting them.

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Probing the role of PO stretching mode enhancement in nerve-agent sensors: Simulation of the adsorption of diisopropylfluorophosphate on the model MgO and CaO surfaces

Cited by 14 publications

References 22 publications

Surface Binding of Organophosphates on Silica: Comparing Experiment and Theory

Surface Binding of Organophosphates on Silica: Comparing Experiment and Theory

Hydrolysis of a VX-like Organophosphorus Compound through Dissociative Chemisorption on the MgO(001) Surface

Density Functional Theory Based Studies on the Nature of Raman and Resonance Raman Scattering of Nerve Agent Bound to Gold and Oxide-Supported Gold Clusters: A Plausible Way of Detection

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