Fourier transform infrared photoacoustic spectroscopy study of the adsorption of organophosphorus compounds on heat-treated magnesium oxide

Li, Yong Xi; Schlup, John R.; Klabunde, Kenneth J.

doi:10.1021/la00055a018

Cited by 85 publications

(123 citation statements)

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“…The high surface area and the intrinsically high surface reactivity of MgO nanocrystals make these materials especially effective as adsorbents [6]. In fact, they have been called "destructive adsorbents" because of their tendency to adsorb and simultaneously destroy by bond breaking processes a series of toxic chemicals [6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Structures and Stabilities of Alkaline Earth Metal Oxide Nanoclusters: A DFT Study

Batra

Gaba

Issar

et al. 2013

Journal of Theoretical Chemistry

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The stability orders of a number of alkaline earth oxide cluster isomers (MO) , M = Mg, Ca, Sr, Ba and 1 ≤ ≥ 6 have been determined by means of density functional theory studies using the LDA-PWC functional. Among the candidate structures, the hexagonal-ring-based isomers and the slab shapes are found to display similar stabilities. Stacks of hexagonal (MO) 3 rings are found to be the slightly preferred growth strategy among the (MgO) 6 , isomers. In contrast, the slab structures are slightly preferred for the other alkaline metal oxide (MO) 6 clusters. An explanation based on packing and aromaticity arguments has been proposed. This study may have important implications for modeling and understanding the initial growth patterns of small nanostructures of alkaline earth metals.

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Section: Introductionmentioning

confidence: 99%

Structures and Stabilities of Alkaline Earth Metal Oxide Nanoclusters: A DFT Study

Batra

Gaba

Issar

et al. 2013

Journal of Theoretical Chemistry

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“…The study of the detection of organophosphorus compounds on SnO 2 and ZnO doped by MgO and CaO [24] has suggested that the basic oxide additives are effective in aiding dissociative adsorption of DMMP on the oxide surface. Other investigations of the interactions of organophosphorus compounds on nanoscale MgO particles using the Fourier Transform Infrared Photoacoustic Spectroscopy [25][26][27] have revealed that these compounds are physisorbed and strongly chemisorbed through the oxygen atom of the P=O bond. Even at room temperature and up to 190°C the chemisorbed compounds began to decompose, at 500°C complete decomposition took place releasing mainly formic acid plus some methanol [25].…”

Section: Introductionmentioning

confidence: 99%

“…Other investigations of the interactions of organophosphorus compounds on nanoscale MgO particles using the Fourier Transform Infrared Photoacoustic Spectroscopy [25][26][27] have revealed that these compounds are physisorbed and strongly chemisorbed through the oxygen atom of the P=O bond. Even at room temperature and up to 190°C the chemisorbed compounds began to decompose, at 500°C complete decomposition took place releasing mainly formic acid plus some methanol [25]. In the case of DMMP, a proposed reaction scheme for the decomposition involves a loss of CH 3 O followed by its oxidation by a second DMMP molecule [26,27].…”

Section: Introductionmentioning

confidence: 99%

Adsorption of dimethyl methylphosphonate and trimethyl phosphate on calcium oxide: an ab initio study

2008

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Ab initio study of the adsorption of dimethyl methylphosphonate (DMMP) and trimethyl phosphate (TMP) on three types of models simulating the calcium oxide surface (non-hydroxylated Ca 4 O 4 , completely hydroxylated Ca 4 O 4 (OH) 2 H 2 , and partially hydroxylated Ca 4 O 4 (OH)H) was performed. The target molecule and the surface hydroxyl groups were optimized while the CaO fragment was kept frozen. The intermolecular interactions were investigated applying Bader's Atoms in Molecules theory. The maps of electrostatic potential of the studied adsorption systems were also produced. The interaction energies of studied adsorption systems corrected by the basis set superposition error were obtained. The most energetically favorable adsorption of DMMP and TMP was found at the configuration where the oxygen atoms of the P=O and methoxy groups point toward the Ca cation of the surface. The P atom points toward the O atom of the surface and forms a P-O chemical bond. This configuration was revealed for the non-hydroxylated and partially hydroxylated CaO-DMMP and CaO-TMP systems. The presence and number of surface hydroxyl groups on the CaO models play a key role in the adsorption of the studied compounds. DMMP and TMP were found to be much less stable on the completely hydroxylated CaO surface where they are adsorbed only via weak electrostatic interactions and H-bonding to the surface oxygen atoms and hydroxyl groups. TMP was found to be slightly more stable on this type of surface than DMMP. The difference in stability is even larger if one compares this TMP system with the complex of tabun adsorbed on completely hydroxylated CaO surface model (Michalkova et al. Chem Phys Lett 438:72, 2007).

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“…Li et al 19,48 mostraram que a reação de água com a superfície de MgO contribui para aumentar a capacidade catalítica desse óxido em degradar compostos OP. A partir desses resultados verificou-se que o MgO pode ser um potencial catalisador para a hidrólise do VX.…”

Section: Mgo E Brucitaunclassified

“…Por outro lado, mesmo permanecendo adsorvidos, em temperatura ambiente já se observa a formação dos fragmentos da decomposição da molécula de DMMP sobre o MgO. 48 Portanto, como a dissociação da molécula de DMPT é a etapa determinante para a espontaneidade termodinâmica da hidrólise catalítica na superfície de MgO(001), a análise da barreira energética para a reação elementar R2 é essencial para verificar a taxa reacional desse processo.…”

Section: Figura 5 Variação Da Energia Livre De Gibbs Para As Reaçõesunclassified

Theoretical Chemistry at the Service of the Chemical Defense: Degradation of Nerve Agents in Magnesium Oxide and Hydroxide Surface

Alvim¹,

Vaiss²,

Leitão³

et al. 2014

Revista Virtual De Química

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Abstract:The Pró-Defesa funding of projects was a joint initiative of CAPES and the Ministry of Defense to fund research in defense. In this article we review the main scientific results obtained in the project "Formação de Pessoal Qualificado em Química Quântica Computacional para Atuação na Área de Defesa Química", funded by the first edition of Pró-Defesa in 2005, which involved a collaboration between the Departments of Chemistry of the Federal University of Juiz de Fora and of the Military Institute of Engineering. The main goal of this project was to study, using theoretical-computational methods, the potential of magnesium oxide and hydroxide surfaces to degrade organophosphorus (OP) substances used as warfare agents, also known as neurotoxics. These substances inhibit the acetylcholinesterase, enzyme of fundamental role in the central nervous system. The VX (O-ethyl-S-(2-diisopropylethylamino) ethyl methylphosphonothioate) and sarin (isopropyl methylphosphonofluoridate) agents are some of the main neurotoxic agents, thus the search for ways to degrade them is considerably important. In this paper, we present theoretical investigations of two chemical degradation processes of organophosphates: the hydrolysis of a VX-like OP compound (O,S-dimethyl methylphosphonothioate, DMPT) by the dissociative chemisorption on the MgO(001) surface and the degradation of sarin by a surface of magnesium hydroxide Mg(OH) 2 , known as brucite. These processes were studied by the combination of density functional theory (DFT) with periodic boundary conditions, an approach that is the state of the art of the theoretical methods for this type of problem. In the case of DMPT, we proposed a degradation mechanism that involves degradation reactions of DMPT and water molecules in the presence of two types of MgO(001) surface models: terrace and Al-doped. Conformations, free energy differences, transition states and reaction barriers were calculated. We showed that the MgO(001) surface acts as a possible catalyst for the degradation of VX, but with higher selectivity than the Al-doped surface when compared with sites without defects on the terrace. These results may have important applications as well as to serve as reference for further studies on the decomposition of VX. In the degradation process of sarin using brucite, we proposed four elementary reactions for the global mechanism. We analyzed the adsorption of sarin on the brucite layer through the fluorine and the phosphonyl oxygen atoms (P=O). The two transition states correspond to a hydroxyl anion motion toward the phosphorus atom and to a fluoride moving toward the hydroxyl vacant position; the activation barrier for the rate-limiting step, corresponds to adsorbed sarin attacked by the brucite hydroxyl. The products of the global reaction were an isopropyl methylphosphonate molecule and [Mg(OH) 2−x ]F x . The results of the deactivation process of sarin using a brucite surface show the potential of layered hydroxides to degrade OP compounds. Also the results of this resea...

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Fourier transform infrared photoacoustic spectroscopy study of the adsorption of organophosphorus compounds on heat-treated magnesium oxide

Cited by 85 publications

References 0 publications

Structures and Stabilities of Alkaline Earth Metal Oxide Nanoclusters: A DFT Study

Structures and Stabilities of Alkaline Earth Metal Oxide Nanoclusters: A DFT Study

Adsorption of dimethyl methylphosphonate and trimethyl phosphate on calcium oxide: an ab initio study

Theoretical Chemistry at the Service of the Chemical Defense: Degradation of Nerve Agents in Magnesium Oxide and Hydroxide Surface

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