Studying the Formation of Choline Chloride- and Glucose-Based Natural Deep Eutectic Solvent at the Molecular Level

The liquid waste is the major source of waste, which usually generated from academic laboratories and industry during the extraction, separation, chemical synthesis, and pretreatment processes. These chemical and engineering processes require more solvents. In this regard, there is a need to develop more environmentally friendly, cheaper, non-toxic solvents that are harmless to humans and the environment. In this regard, deep eutectic solvents (DES) and their derivatives so-called natural deep eutectic solvents (NADES) are a new field in the search for green alternative solvents. In our work, the formation of choline chloride-based NADESs using density functional theory (DFT) calculations, and classical all-atom molecular dynamics (MD) simulation was studied in detail using Gaussian09 and Gromacs software's. Next, the ground state geometry optimizations were performed in the gas phase using DFT B3LYP 6-31 + G(d) level of theory. Moreover, classical all-atom MD simulations were implemented using Gromos force field. After the modeling and simulations, the DFT calculation results revealed the formation of NADESs via formation (creation) of binding between chlorine and choline, and chlorine and glucose. At the same time, the results of classical all-atom MD simulations, based on the time average of the equilibrated production run of MD simulations, stated that the nitrogen atom of choline ion and chloride ion has greater interactions, while chloride ion has also greater interaction with glucose during formation of NADES. The outcomes of both DFT and classical all-atom MD simulations are in good agreements.