Microstructure, dynamics, and temperature behavior of L-menthol, salicylaldoxime, and their binary mixture: a molecular dynamics simulation study

Deep eutectic solvents are mixtures of various substances classified as liquid supramolecular systems, which have a wide range of scientific, practical, and technological applications. This study investigated the molecular aspects involved in creating a deep eutectic binary mixture of L-menthol and salicylaldoxime using classical molecular dynamics simulations. We focused on the microstructure and dynamics of intermolecular interactions for both the individual components and their binary mixture at temperatures of 298, 333, and 353 K. Our findings revealed that, at a macroscopic scale, there is a nearly uniform distribution of components in the binary mixture of L-menthol and salicylaldoxime, with no phase separation or domain formation observed within the examined temperature range. We noted a significant increase in self-diffusion coefficients in the formation of the binary mixture, with these coefficients further increasing at higher temperatures. Through hydrogen bonding analysis and radial distribution functions, we demonstrated that the formation of the binary mixture resulted in changes to the solution’s microstructure, including a considerable reduction in the number of intermolecular hydrogen bonds. Consequently, the transition to a liquid phase at room temperature for this eutectic composition is primarily driven by van-der-Waals attractions between the hydrophobic portions of the components. Our theoretical findings are significant from both scientific and practical perspectives, as they provide valuable insights into the relationship between the microscopic structure of a deep eutectic mixture and its transport properties.