Towards an Understanding of the Mutual Solubilities of Water and Hydrophobic Ionic Liquids in the Presence of Salts: The Anion Effect
authors Tome, LIN; Varanda, FR; Freire, MG; Marrucho, IM; Coutinho, JAP
nationality International
journal JOURNAL OF PHYSICAL CHEMISTRY B
keywords AFFECT PROTEIN STABILITY; HOFMEISTER SERIES; MOLECULAR-ORGANIZATION; PHASE-BEHAVIOR; H2O; MACROMOLECULES; DENATURANTS; EXTRACTION; MECHANISM; SOLVENTS
abstract The understanding of the specific interactions between salt ions and ionic liquids (ILs) in aqueous solutions is relevant in multiple applications. The influence of a series of anions on the solubility of 1-butyl-3-methylimidazolium tricyanomethane in aqueous environment was here studied. This study aims at gathering further information to evaluate the recently proposed(1,2) mechanisms of salting-in- and salting-out-inducing ions in aqueous solutions of ILs and to provide insights at the molecular-level on the phenomena occurring in these systems. The observed effect of the inorganic species on the aqueous solubility of the ionic liquid qualitatively follows the Hofmeister series, and it is dependent on the nature and concentration of the anions. The liquid-liquid equilibrium data and (1)H NMR results here reported support a model according to which salting-in- and salting-out-inducing ions operate by essentially different mechanisms. While salting-out is an entropically driven effect resulting from the formation of hydration complexes and the increase of the surface tension of cavity formation, the salting-in phenomena is a consequence of the direct binding of the ions to the hydrophobic moieties of the IL. Further evidence here obtained suggests that the interactions of the inorganic ions are not only established with the cation of the IL, but also with the anion, with the observed solubility effect the result of a balance between those two types of interactions.
publisher AMER CHEMICAL SOC
issn 1520-6106
year published 2009
volume 113
issue 9
beginning page 2815
ending page 2825
digital object identifier (doi) 10.1021/jp810141d
web of science category Chemistry, Physical
subject category Chemistry
unique article identifier WOS:000263732700033
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journal impact factor 3.146
5 year journal impact factor 3.101
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