Inorganic salts in purely ionic liquid media: the development of high ionicity ionic liquids (HIILs)

Abstract

This work explores the possibility of increasing the ionicity of ionic liquids via the solubilization of inorganic salts in their midst. The resulting purely ionic media-distinct ionic liquid plus inorganic salt mixtures-are liquid in an extensive concentration range and can be aptly denominated High Ionicity Ionic Liquids (HIILs).

Nucleic acid bases in 1-alkyl-3-methylimidazolium acetate ionic liquids: A thermophysical and ionic conductivity analysis

“…This fact can probably be attributed to the strong interactions between the solute and the ionic liquid [41], which agrees with the strong hydrogen bonding between the nucleobases and both the IL anion and cation, determined by NMR spectroscopy in a previous study concerning the dissolution mechanism of nucleobases in 1,3-dialkylimidazolium acetate ILs [8]. We have also observed similar phenomena of increasing density with the solute concentration when mixtures of ionic liquids and simple inorganic salts were studied [42]. In this last example, molecular dynamic studies evidenced the strong interactions that also occur in the studied systems.…”

Solubility of inorganic salts in pure ionic liquids

“…In the most highly concentrated IL solution, the inorganic salt ions can be easily accommodated within the local charge-ordered structure of the IL. When the concentration of inorganic salt is increased, the small size and high-charge density of the IS cation will start to out-compete the interactions between the IL cation and the anions and the polar network of the IL/IS mixture will start to contract relative to the original IL structure [12]. The size, shape and charge dispersion of the IL cation probably allow it to find new orientations and accommodate itself inside this new shrinking ionic fluid network -at least up to a certain IS concentration, beyond which the separation of an IS precipitate from a saturated IL/IS solution will occur.…”

“…Other studies have introduced hydrogen bonding between ions by functionalizing the alkyl chains [11]. In contrast, only one previous work [12] has analysed, in a broad sense, the increase of IL ionicity via the solubilization of inorganic salts (ISs) in the ionic milieu. This study proved the increase ionicity in two IL/IS systems, 1-ethyl-3-methylimidazolium ethylsulfate/acetate ([C 2 C 1 Im][C 2 SO 4 ], [C 2 C 1 Im][OAc]), combined with ammonium thiocyanate, [NH 4 ][SCN].…”

Separation of azeotropic mixtures using high ionicity ionic liquids based on 1-ethyl-3-methylimidazolium thiocyanate

“…[ 2 0 _ T D $ D I F F ] Angell and co-workers [7][8][9] showed that most ILs fall below this line, acknowledging the strong interactions between anions and cations. However, previous work from our laboratory established that ionic liquid[ 2 1 _ T D $ D I F F ] 's ionicity could be improved by the dissolution of simple inorganic salts (IS) in their milieu [10,11]. In the same line of thought, the use of a mixture of ILs to increase the solvent ionicity might allow the "design" of a new solvent, with specifically finetuned properties including ionicity.…”