Strong Microheterogeneity in Novel Deep Eutectic Solvents

Abstract

With the increasing application of template assisted syntheses in deep eutectic solvents and successful application of hydrophobic deep eutectic solvents in extraction processes, where microheterogeneity plays a major role, suggestions for novel deep eutectic solvents which exhibit strong microheterogeneity are desirable. Therefore, classical molecular dynamics simulations were carried out on deep eutectic solvent systems constructed of choline chloride and some of its derivatives mixed with ethylene glycol in a molar composition of 1 : 2 since this is the optimal parent composition. The derivatives consisted of a series of elongated alkyl side chains and elongated alcohol side chains. Of these series only choline chloride ethylene glycol has been investigated experimentally, the other systems are suggested and theoretically investigated as possible target for synthesis. Our domain analysis supported by the clear distinction of polar and nonpolar parts from the electrostatic potentials reveals that strong microheterogeneity within these novel hypothetical deep eutectic solvents exists. Rather stretched than crumbled side chains maximize possible interaction sites for both polar and nonpolar parts which make the suggested compounds valuable objectives for experiments in order to exploit the microheterogeneity in deep eutectic solvents.

Do Deep Eutectic Solvents Form Uniform Mixtures Beyond Molecular Microheterogeneities?

“…Fluorescence and infrared spectroscopy studies demonstrated that changing the hydrocarbon chain length of both HBA and HBD affects the spatial and dynamic heterogeneity of the ionic DESs. [26][27][28] This view is in line with conclusions from WANS on alkylammonium bromide:glycerol DESs 29 and MD simulation of choline chloride derivatives:ethylene glycol DESs 30 that have related the microheterogeneous structure of DESs to the segregation of the apolar and polar groups of the cationic molecules into separated domains. The formation and the percolation of these domains are favored by larger chains, which reveal the role of the amphiphilic character of the cationic moieties.…”

Computer Simulations of Deep Eutectic Solvents. Challenges, Solutions, and Perspectives

“…Control of heterogeneity is an important task for the development of DESs for extraction and other separation applications [219,220]. Alizadeh et al [220] studied heterogeneity in DESs based on ChCl and its depravities with different lengths of the alkyl chain.…”

Structure and hydrogen bonds of hydrophobic deep eutectic solvent‐aqueous liquid–liquid interfaces

“…They found that the cation chain length affects the density and transport properties of DESs. Alizadeh et al 39 Several simulation and experimental efforts have been conducted to investigate the interfacial properties of DESs. Most of these studies focus on the behavior of DES molecules near solid surfaces.…”

“…They found that the cation chain length affects the density and transport properties of DESs. Alizadeh et al 39 investigated the microheterogeneity of DESs composed of choline chloride and its derivatives mixed with ethylene glycol using MD simulations. Their results show distinct polar and nonpolar parts in these DESs.…”