Computational investigation of the microstructural characteristics and physical properties of glycerol-based deep eutectic solvents

Recently, there has been significant interest in the possibility of using deep eutectic solvents (DESs) as novel green media and alternatives to conventional solvents and ionic liquids (ILs) in many applications. Due to their attractive properties, such as their biodegradability, low cost, easy preparation, and nontoxicity, DESs appear to be very promising solvents for use in the field of green chemistry. This computational study investigated six glycerol-based DESs: DES₁ (glycerol:methyl triphenyl phosphonium bromide), DES₂ (glycerol:benzyl triphenyl phosphonium chloride), DES₃ (glycerol:allyl triphenyl phosphonium bromide), DES₄ (glycerol:choline chloride), DES₅ (glycerol:N,N-diethylethanolammonium chloride), and DES₆ (glycerol:tetra-n-butylammonium bromide). The chemical structures and combination mechanisms as well as the sigma profiles and sigma potentials of the studied DESs were explored in detail. Moreover, density, viscosity, vapor pressure, and IR analytical data were predicted and compared with the corresponding experimental values reported in the literature for these DESs. To achieve these goals, the conductor-like screening model for realistic solvents (COSMO-RS) and the Amsterdam Density Functional (ADF) software package were used. The predicted results were found to be in good agreement with the corresponding experimental values reported in the literature. Further theoretical investigations are needed to confirm the experimental results—regarding both properties and applications—reported for these DESs.