Assessment of the properties of natural-based chiral deep eutectic solvents for chiral drug separation: insights from molecular dynamics simulation

Abstract

The structural and physicochemical properties of chiral deep eutectic solvents (DESs) consisting of racemic mixtures of menthol and acetic acid (DES1), racemic mixtures of menthol and lauric acid (DES2), and racemic mixtures of menthol and pyruvic acid (DES3) for enantioselective extraction processes are investigated. Structural results, such as the radial distribution function (RDF) and the combined distribution function (CDF), indicate that the hydroxyl hydrogen of menthol has a dominant interaction with the carbonyl oxygen of the acids in the considered DESs. The number of hydrogen bonds and non-bonded interaction energies formed between S-menthol and HBDs are larger than those with R-menthol, resulting in the self-diffusion coefficient of S-menthol being larger than that of R-menthol. Therefore, it can be said that the proposed DESs are good candidates for the separation of drugs with S chirality. The effects of acid type on the density and isothermal compressibility of DESs show the behaviour of DES2 > DES3 > DES1 and DES1 > DES3 > DES2, respectively. Our results provide a better perspective on new chiral DESs at the molecular level for enantioselective processes.