Brillouin and NMR spectroscopic studies of aqueous dilutions of malicine: Determining the dilution range for transition from a “water-in-DES” system to a “DES-in-water” one

Phase behavior of aqueous solutions of ethaline deep eutectic solvent

“…From a thermodynamic or structural point of view, it may be considered that the unfrozen water molecules retained in the DES system during ice formation are involved in the formation of stable structures. Recent Brillouin studies have indicated the existence of a crossover in the sound propagation velocity in different DES for an aqueous dilution around W=30% [17,18]. Along with NMR data, this result has been interpreted as the transitioning of the liquid structure from a H 2 O-based to a DES-based H-bonded network.…”

“…W >50%), the aqueous DES solution evolves from the "DES-in-water" to "water-in-DES" situation, according to the designation introduced by ref. [18]. This transformation is eventually arrested when W g '=30% (i.e.…”

“…The integrity of DES could be destroyed in biphasic aqueous systems, while its local arrangement could be preserved in single-phase aqueous DES mixtures up to a moderate degree of hydration [1,11]. The physical properties of water-ionic liquids and water-DES mixtures, including excess properties, viscosity, acoustic, structural and optical properties have been studied around ambient temperature and above [1,[12][13][14][15][16][17][18][19].…”

Unravelling the nature of citric acid:l-arginine:water mixtures: the bifunctional role of water

“…Further, FTIR can be used to detect intermolecular interactions because they change the dipole moments of the involved functional groups, shifting the respective signals in the FTIR spectra 17,24,25 . NMR spectroscopy can be used to identify hydrogen bonding interactions or modifications through shifts in proton NMR spectra [26][27][28] .…”

Carbon and carbon composites obtained using deep eutectic solvents and aqueous dilutions thereof

“…Both the ''DES-in-water'' and the ''water-in-DES'' with low water contents -e.g., one or two moles of water per mole of DESsystems have been widely studied and agreement exists with regard to their respective natures -e.g., a simple aqueous dilution of the individual DES components in the former case 73,74 or water playing the role of a second small HBD in the latter one. [75][76][77] However, less agreement exists with regard to the nature of intermediate dilutions; this is the ''water-in-DES'' system with high water contents where the water fraction is yet too low to promote the DES rupture and dissolve its components. Interestingly, in a recent work dealing with pseudo-concentrated aqueous solutions of DES composed of resorcinol, urea, and ChCl, we demonstrated that water played the role of an additional HBD or HBA and, hence, was interstitially accommodated within the DES-based 3D H-bonded network, thus forming the ''water-in-DES'' system.…”