Theoretical Study of the Microhydration the Chemical Warfare Agent Sulfur Mustard

Abstract

A microhydration study of sulfur mustard (SM) was carried out using M06-2X, B3LYP, B3LYP-D3, and MP2 levels of theory with the 6-311++G­(2d,2p) basis set. The changes in energetics, structural parameters and vibrational wavenumbers following the addition of up to three discrete water molecules to SM were analyzed. We observed slight changes in the geometry of SM upon microhydration. The stability of hydrated clusters is due to weak C–H···O–H hydrogen bonds. The free energy change for the formation of the clusters is positive at room temperature and becomes exergonic when the temperature decreases. The infrared stretchings of C–Cl of SM and O–H of water are redshifted upon the addition of water molecules. The findings from this work add to the literature of hydrated SM and can be useful in its detection and subsequent destruction.

Colorimetric Detection of Sulfur Mustard with 4-(p-Nitrobenzyl)pyridine and Its Derivatives

“…The geometry optimizations of the related compounds were performed with the Gaussian 09 program based on the density functional theory (DFT) with B3LYP , /6-311+G­(2d,p) , with universal continuum solvation (SMD) models or in the gas phase . The frequency calculation (at 298.15 K and 1 atm) of the optimized compounds showed no imaginary frequency, which confirms that the geometry energy is in the minimum state.…”

“…The excited state properties were calculated using the time-dependent density functional theory (TD-DFT) formalism at the same level of theory. For transition state calculations of SM, ωb97xd/def2-tzvp basis set , with universal continuum solvation (SMD) models or in the gas phase was applied. The free energy of chloride in solution was calculated by adding the free energy of solvation of the chloride anion (Δ G solvation = −87 kcal/mol in water and Δ G solvation = −65.6 kcal/mol in acetone) to the free energy of chloride calculated by DFT in the gas phase .…”