Theoretical Study of the Adsorption of Organophosphorous Compounds to Models of a Silica Surface

Abstract

We present a study of the interaction of seven organophosphorous (OP) compounds with models of a silica surface using electronic structure calculations. Two of the OP species are chemical-warfare nerve agents (sarin and soman) and the rest are organophosphate (methyl dichlorophosphate, dimethyl chlorophosphate, and trimethyl phosphate) or organophosphonate (dimethyl methylphosphonate and diisopropyl methylphosphonate) mimics utilized in recent experiments. Calculations that approximate an amorphous silica surface by a simple gas-phase silanol molecule qualitatively reproduce the trend in binding energies determined in recent ultrahigh vacuum experiments. These calculations also show that, of the various atoms in the OP species that can accept hydrogen bonds from silanol groups, the oxygen atom that forms a double bond with the central phosphorus atom provides the largest binding energy, followed first by the remaining oxygen atoms and then by the halogen atoms. Quantitative comparisons with experiments are established by using calculations that more rigorously appoximate an amorphous silica surface with silica clusters that contain one or two silanol groups. MP2 calculations of the binding energies extrapolated to the complete-basis-set limit in a cluster model exhibiting a single isolated silanol group differ from the recent ultrahigh vacuum experimental values by less than 1 kcal/mol for many of the OP compounds examined. Calculations on a silica cluster with two silanol groups reveal the possibility of formation of two hydrogen bonds with the OP compounds and produce binding energies that are also consistent with other recent measurements. Symmetry-adapted perturbation theory is used to provide deeper insight into the origin of the exceptionally strong hydrogen bonds established between silica surfaces and OP compounds.

Mesoporous-silica nanofluidic channels for quick enrichment/extraction of trace pesticide molecules

“…Benefited from the confined space of the nanofluidic channels, chemical interaction between the target analyte molecules and the ≡Si-OH groups in the nano-channels can be dramatically enhanced 48 . In the nanofluidic channels, the OP target molecules can be quickly captured and effectively enriched by the ≡Si-OH groups on the inwalls of the nanofluidic channels via specific adsorption with the P=O (or P=S) groups of the OP molecules 49 50 51 52 53 . With the sample continually flowing through the nano-channels, the trapped OP molecules can be pre-concentrated.…”

Investigation of interactions between organophosphorus compounds and TiO2 modified microcantilevers for molecule detection in air

“…In this context, several studies have focused on understanding the adsorption/desorption mechanisms of OPs on different materials. Among them, theoretical studies 16 and solid-state MAS NMR 17 have given interesting results on the adsorption reaction of OPs molecules on oxide surfaces such as silica or manganese oxide. An infrared study was used to describe the type of reaction involves for three organophosphorous simulants (MDCP, DMMP, TCP) on silicon oxide surface 18 .…”

Mechanistic Insight into the Molecular TiO2-Mediated Gas Phase Detoxication of DMMP: A Theoretical Approach

“…Organophosphorus compounds − (OPCs), one of the most nefarious of synthetic chemical reagents, have motivated researchers to investigate their convenient detection and detoxication processes. OPCs are mainly characterized by the presence of a phosphorus­(V) center with a terminal oxide and three single-bonded substituents (alkyl, alkoxyl, sulfhanyl, etc.).…”

“…is of great interest at present. Solid surfaces as well as powder metal oxides, for example, brucite, MgO(001), TiO 2 , − SiO 2 , , Rh(100), Mo(111), Pt(111), Ni(111), Pd(111), Al 2 O 3 , − Fe 2 O 3 , and Y 2 O 3 have already been used for degradation purposes. Among all of these decomposing reagents, degradation using the TiO 2 surface and TiO 2 powder are very well known.…”