Promising Technological and Industrial Applications of Deep Eutectic Systems

Abstract

Deep Eutectic Systems (DESs) are obtained by combining Hydrogen Bond Acceptors (HBAs) and Hydrogen Bond Donors (HBDs) in specific molar ratios. Since their first appearance in the literature in 2003, they have shown a wide range of applications, ranging from the selective extraction of biomass or metals to medicine, as well as from pollution control systems to catalytic active solvents and co-solvents. The very peculiar physical properties of DESs, such as the elevated density and viscosity, reduced conductivity, improved solvent ability and a peculiar optical behavior, can be exploited for engineering modular systems which cannot be obtained with other non-eutectic mixtures. In the present review, selected DESs research fields, as their use in materials synthesis, as solvents for volatile organic compounds, as ingredients in pharmaceutical formulations and as active solvents and cosolvents in organic synthesis, are reported and discussed in terms of application and future perspectives.

Glycerol-based NaDES as green solvents for ultrasound-assisted extraction of phycocyanin from Arthrospira platensis—RSM optimization and ANN modelling

“…NaDES were first introduced by Choi et al [25]. They are defined as organic compounds with a melting point which is considerably lower than that of each component [25,26]. NaDES are obtained by mixing hydrogen bond-donors with a hydrogenbond acceptor using a suitable molar ratio [26][27][28], based on natural compounds.…”

“…They are defined as organic compounds with a melting point which is considerably lower than that of each component [25,26]. NaDES are obtained by mixing hydrogen bond-donors with a hydrogenbond acceptor using a suitable molar ratio [26][27][28], based on natural compounds. They are mostly composed by primary metabolites, such as organic acids, amino acids, and sugars.…”

Phenol-cyclohexanol eutectic mixtures: Phase diagram and microscopic structure by experimental and computational studies

“…They show most of the properties of the ionic liquids (ILs), including low volatility and high solvating and extracting properties, with the advantage that they are usually less toxic variants of the room temperature ionic liquids. As ILs, ESs exhibit a wide number of tunable physicochemical properties [1][2][3][4] that allow their utilization in a growing number of fields, including extraction, (bio) synthesis, catalysis, electrochemistry, and carbon dioxide capture [5][6][7][8][9]. The majority of ESs are easily prepared by mixing biodegradable starting materials, like organic or inorganic salts, with organic acids or organic neutral molecules.…”

Behavior of Ternary Mixtures of Hydrogen Bond Acceptors and Donors in Terms of Band Gap Energies

“…Hydrogen bond-based systems have been affirmed during the last 20 years as one of the most recurrent topics in the scientific literature [ 1 ]. In particular, the possibility to combine in a eutectic molar ratio Hydrogen Bond Acceptors (HBAs) and Hydrogen Bond Donors (HBDs) and form liquid mixtures at room temperature with increased solvent ability, which was reported for the first time by Abbott et al in 2003 (choline chloride/urea 1:2) [ 2 ], created opportunity for many applications in several research and industrial sectors.…”

“…At the molecular level, most of the DESs can be described according to the hole theory [ 8 ] and rationalized as systems made by an intense hydrogen bond network decorated with randomly distributed holes, where the ions can move along the network by jumping from one hole to another [ 9 ]. This supramolecular behavior gives to the system peculiar properties such as an increased density, a decreased viscosity, and a low conductivity [ 1 ]. On the basis of such characteristics, DESs have found many applications as media for biomass treatment [ 10 ], metal extraction [ 11 ], solvents for Volatile Organic Compounds (VOCs) [ 12 , 13 ], templates for ionothermal synthesis [ 14 , 15 , 16 ], or non-innocent solvents in organic synthesis [ 17 , 18 , 19 , 20 , 21 ], as well as additives in pharmaceutical formulations [ 1 , 22 , 23 ].…”