Structure and Hydrogen Bonds of Hydrophobic Deep Eutectic
Solvent-Aqueous Liquid-Liquid Interfaces
Abstract
Hydrophobic deep eutectic solvents (DESs) emerge as candidates to
extract organic substrates from aqueous solutions. The DES-aqueous
liquid-liquid interface plays a vital role in the extraction ability of
hydrophobic DES because the non-bulk structure of molecules at the
interface could cause thermodynamic and kinetic barriers. One question
is how the DES compositions affect the structural features of the
DES-aqueous liquid-liquid interface. We investigate the density profile,
dipole moment and hydrogen bonds of eight hydrophobic DES-aqueous
liquid-liquid interfaces using molecular dynamics simulations. The eight
DESs are composed of four organic compounds: decanoic acid, menthol,
thymol, and lidocaine. The simulation results show the variations of
dipole moment and hydrogen bond structure and dynamics at the
liquid-liquid interfaces. Such variations could influence the extraction
ability of DES through adjusting the partition and kinetics of organic
substrates in the DES-aqueous biphasic systems.