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

Theoretical study of gas-phase detoxication of DMMP and DMPT using ammonia-borane and its analogous compound

The detoxication of DMMP (Dimethyl methylphosphonate) and DMPT (O, S-dimethyl methylphosphonothiolate) via hydrogenation have been investigated computationally employing density functional theory (DFT). In this present study, we aim to explore the direct molecular H₂ assisted as well as ammonia-borane (NH₃BH₃) and 3-methyl-1,2-BN-cyclopentane (denoted as cy-AB) assisted hydrogenation pathways of DMMP and DMPT in order to detoxify them. The detoxication of DMMP has been carried out by successive elimination of two -OMe groups. However, in the case of DMPT, two possibilities have been identified because of two different substituents, -OMe and -SMe. In possibility-I, the elimination of the -OMe group occurs at the beginning, followed by the -SMe group, whereas in possibility-II, the reverse order of elimination occurs for -OMe and -SMe groups. During the detoxication of DMMP using both NH₃BH₃ and cy-AB as the assisting reagents, the first step has been identified as the rate-determining step (RDS) in which the hydrogens attached to the N- and B-centers of NH₃BH₃ are transferred to the O-center of PO and P-center, respectively. In harmony with DMMP detoxication, for DMPT also, analyzing the activation barriers, it can be articulated that for both NH₃BH₃ and cy-AB assisted pathways, both the possibilities are equally feasible as in both the possibilities the common first step is the RDS. Therefore, our computational study is designed to explore the assisting efficiency of NH₃BH₃ and its cyclic analogue for detoxifying the OPCs.

Solar light decomposition of warfare agent simulant DMMP on TiO2/graphene oxide nanocomposites

Solar light-induced photodecomposition of organophosphorus warfare agent simulant dimethyl methylphosphonate (DMMP) on the surfaces of TiO₂/graphene oxide (GO) nanocomposites was studied by in situ DRIFT spectroscopy.

Ultrafast coherent vibrational dynamics in dimethyl methylphosphonate radical cation

Coherent vibrational dynamics drive dissociation of dimethyl methylphosphonate (DMMP) radical cation.

A Theoretical and Mass Spectrometry Study of Dimethyl Methylphosphonate: New Isomers and Cation Decay Channels in an Intense Femtosecond Laser Field

Using both mass spectrometry with intense femtosecond laser ionization and high-level computational methods, we have explored the structure and fragmentation patterns of dimethyl methylphosphonate (DMMP) cation. Extensive search of the geometries of both neutral and positively charged DMMP yields new isomers that are appreciably lower in total energy than those commonly synthesized using the Michaelis-Arbuzov reaction. The stability of the standard isomer with CH₃PO(OCH₃)₂ topology is found to be due to the presence of high barriers to isomer interconversion that involves several transition states. Our femtosecond laser ionization experiments show that the relative yields of the major dissociation products as a function of peak laser intensity correlate well with the theoretical estimates for the energies of the DMMP⁺ decay via various channels. In contrast, the peak laser intensities required for observation of minor dissociation products exhibit no correlation with the computed decay energies, which suggests that barrier heights and/or excited electronic states of DMMP⁺ determine its preferred fragmentation pathways in an intense femtosecond laser field.