posted on 2020-03-10, 20:03authored bySupreet Kaur, Aditya Gupta, Hemant K. Kashyap
Recently,
it has been observed that choline chloride ([Ch][Cl])
based deep eutectic solvents (DESs) may possess nanostructures in
which chloride ions play a major role by providing a backbone for
the bridged hydrogen bond network. In this article, we present a fundamental
study on the role of hydration on the nanostructure of a [Ch][Cl]
based DES, ethaline. In this molecular dynamics investigation, we
observe a nonlinear change in the structural morphology of ethaline
on gradual addition of water. The initiation of disruption of the
native structure of the DES at 40 mol % of water is clearly observed,
after which the increasing dilution rapidly destructs the long-range
as well as short-range intermolecular interactions existing between
the constituent species of pure ethaline. Herein, we find that, at
very high hydration level, chloride ion no longer acts as a bridge
between the choline cation and ethylene glycol, as it forms strong
hydrogen bond with water. Intriguingly, the strengthening of hydrogen
bonding interactions among the ethylene glycol molecules is observed
on increasing hydration level. Hence, it is predicted that segregation
of ethylene glycol can occur in the pool of aqueous mixtures of [Ch][Cl]
at very high hydration level.