Computational investigation of the dynamics of the constituents in a glucose-based biodegradable deep eutectic solvent.

Atomistically detailed force field is employed to investigate the dynamics of a naturally abundant deep eutectic solvent at 328 K, composed of glucose, urea, and water in a 6:4:1 mass ratio. This study examines key dynamical processes, including translational motion, molecular reorientation, and hydrogen bond relaxation, with timescales ranging from a few picoseconds to a few nanoseconds. Characteristic times associated with the translational and the rotational motion increase with molecular size, i.e., water being the fastest and glucose the slowest. Jump length analysis shows that urea and glucose traverse fractions of their molecular diameters during jumps, suggesting gliding motion. We find that water molecules exhibit strong anisotropic reorientation, which is moderate for urea and nearly absent in the case of glucose molecules. Correlation analysis of analogous transport quantities among the constituents reveals that reorientation of the dipole axis is less coupled to the translational diffusion compared to the reorientation around the dipolar axis. Finally, we observe that hydrogen bond relaxation times for water and urea are highly dependent on the number of hydrogen bonds formed, while for glucose, the slower molecular motion influences its hydrogen-bond relaxation.