Research Progress on Deep Eutectic Solvents and Recent Applications

Abstract

In this study, the classification, composition, preparation methods, and performance parameters of deep eutectic solvents (DESs) and their recent applications in natural product extraction, drug delivery systems, trace metal determination, nanomaterial synthesis, and electrochemistry are systematically summarised through the literature of recent decades, using DESs and applications as keywords. The hydrogen bond acceptors (HBA) of DESs are mainly quaternary ammonium salts (e.g., choline chloride) or amphoteric ions (e.g., betaine); the hydrogen bond donors (HBD) are mostly compounds such as urea, polyols, and sugars. Their melting points are related to hydrogen bonding, their polarities are higher than most ionic liquids, and their viscosities are generally in the range of 0.01–5 Pa·s. Compared with traditional organic solvents and conventional ionic liquids, DESs have higher solubility, with their ability to dissolve metal oxides and insoluble drugs, and have good biodegradability. DESs have high extraction rates in flavonoids and phenols, can increase drug solubility in drug delivery systems, can effectively extract and perform pre-concentration of metals in trace metal determination, can synthesise new nanomaterial, and can be used as electrolytes for electrochemical reactions in electrochemistry. This paper collates the relevant literature on the physicochemical properties and multi-field applications of DESs, which provides a deeper understanding of DESs and looks forward to the future development of DESs

Exploration of novel eco-friendly techniques to utilize bioactive compounds from household food waste: special reference to food applications

“…These properties can be modified using different HBAs and HBDs. DESs are usually less conductive, more viscous, and denser than water (Mu et al, 2023).…”

Natural Deep Eutectic Solvents as Rust Removal Agents from Lithic and Cellulosic Substrates

“…Twenty years ago, the pioneering work of Abbott first reported that mixtures of choline chloride and urea had produced eutectics which were liquids at room temperature with unusual solvent properties [1]. Since then, numerous papers and reviews have been devoted to the development and characterization of several Deep Eutectic Solvents (DESs) in different fields of application [2][3][4][5][6]. In fact, thanks to their peculiar physicochemical properties, to their non-toxicity, biodegradability and biosustainability, and, above all, to their tunability, they can be designed to satisfy different and multiple requirements.…”

Mn-Catalyzed Ligand-Free One-Pot Synthesis of (E)-6,7-Dihydrodibenzo[b,j][1,7]phenanthrolines and (E)-1,2,3,4-Tetrahydrobenzo[b][1,6]naphthyridines through Dehydrogenative Friedlander Annulation/C(sp3)–H Functionalization

“…The HBA includes quaternary ammonium salts like TBAB, ChCl, TBAI, etc., whereas HBD includes alcohols, amide, and acids. The resulting melting point should be lower than those two components and DES is also an alternative to the ionic liquid. − DES has several advantages, including nontoxicity, biodegradability, low cost, easy synthesis, and good thermal stability; it acts as a catalyst as well as a solvent. , …”