Binary Mixtures of Novel Sulfoxides and Water: Intermolecular Structure, Dynamic Properties, Thermodynamics, and Cluster Analysis

TL;DR

This study uses molecular dynamics simulations to analyze the structure, dynamics, and thermodynamics of sulfoxide-water mixtures, revealing high miscibility and composition-dependent properties relevant for biomedical applications.

Contribution

First comprehensive simulation-based analysis of sulfoxide/water mixtures, detailing their intermolecular interactions, thermodynamics, and dynamic behavior across compositions.

Findings

High miscibility of DESO and EMSO with water.

Significant viscosity increase at 30-50 mol% sulfoxide.

Slightly more favorable free energy of mixing for EMSO.

Abstract

Senior dialkyl sulfoxides constitute interest in the context of biomedical sciences due to their abilities to penetrate phospholipid bilayers, dissolve drugs, and serve as cryoprotectants. Intermolecular interactions with water, a paramount component of the living cell, determine performance the sulfoxide-based artificial systems in their prospective applications. Herein, we simulated a wide composition range of the sulfoxide/water mixtures, up to 85 w/w% sulfoxide using classical molecular dynamics to determine structure, dynamics, and thermodynamics as a function of the mixture composition. As found, both diethyl sulfoxide (DESO) and ethyl methyl sulfoxide (EMSO) are strongly miscible with water. DESO and EMSO based aqueous mixtures exhibit similar structure and thermodynamic properties, however, quite different dynamic properties over an entire range of compositions. Strong deviations from an ideal mixture between 30 50 mol% of sulfoxide content leads to relatively high shear viscosities of the mixtures. Free energy of mixing with water is only slightly more favorable for EMSO than for DESO. The results, for the first time, quantify high miscibilities of both sulfoxides with water and motivate comprehensive in vivo investigation of the proposed mixtures.