Theoretical investigation of supramolecular hydrogen-bonded choline chloride-based deep eutectic solvents using density functional theory

The structural properties of choline chloride-based deep eutectic solvents (DESs) are investigated using the molecular dynamics simulations approach. The effect of different donor groups i.e. ethylene glycol, malic acid, tartaric acid, glycerol and oxalic acid with choline chloride acceptor in the formation of supramolecular structures are studied by employing different functionals. Different thermodynamic properties such as heat of formation, charge mobility, interaction energies, electronic energy, zero-point energy, dipole moment, heat capacity, entropy, bond angles and dihedral angles of the eutectic mixture are anticipated. Among all the deep eutectic solvents, DES3 is found to be more stable in terms of an extensive hydrogen-bonded network with maximum heat of formation (-5.94 x 104 eV). The extensive hydrogen bond network in DES3 also leads to substantially higher polarizability (222.124 au), thermal stability (345.14 kcal mol-1), heat capacity (121.43 Calmol-1K) and entropy (222.04 Calmol-1K-1). However, the viscosity of DES1 is found lowest (37 cP) with the highest conductivity (6.34 mS cm-1), dipole moment (16.14 Debye) and electron mobility (0.0919644 eV) and hole mobility (0.0477745 eV). This work will provide a new visualization of the supramolecular structure of choline chloride-based DESs with physical and electronic properties.

Automated summary

This study investigated the structural and thermodynamic properties of choline chloride-based deep eutectic solvents using molecular dynamics simulations, revealing DES3 to be the most stable with extensive hydrogen-bonded network and higher polarizability, thermal stability, heat capacity, and entropy. On the other hand, DES1 showed lower viscosity but higher conductivity, dipole moment, electron mobility, and hole mobility.