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Author(s): Mara G. Freire
Catarina M. S. S. Neves
Artur M. S. Silva
Luís M. N. B. F. Santos
Isabel M. Marrucho
Luís P. N. Rebelo
Jindal K. Shah
Edward J. Maginn
João A. P. Coutinho
Title: 1H NMR and Molecular Dynamics Evidence for an Unexpected Interaction on the Origin of Salting-In/Salting-Out Phenomena
Issue Date: 2010
Abstract: By employing 1H NMR spectroscopy and molecular simulations, we provide an explanation for recentobservations that the aqueous solubilities of ionic liquids exhibit salting-out to salting-in regimes upon additionof distinct inorganic salt ions. Using a typical ionic liquid [1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide], we observed the existence of preferential specific interactions between the low electricalcharge density ("apolar moiety") parts of the ionic liquid cation and the inorganic salts. These a prioriunexpected interactions become increasingly favorable as one moves from salting-out to salting-in effects.More specifically, this interpretation is validated by distinct aqueous solution 1H NMR data shifts in the ionicliquid cation upon inorganic salt addition. These shifts, which are well noted in the terminal and preterminalhydrogens of the alkyl chain appended to the imidazolium ring, correlate quantitatively with solubility data,both for cases where the nature of inorganic salt is changed, at constant concentration, and for those wherethe concentration of a given inorganic salt is varied. Molecular simulations have also been performed permittingus to garner a broader picture of the underlying mechanism and structure of this complex solvation phenomenon.These findings can now be profitably used to anticipate solution behavior upon inorganic salt addition wellbeyond the specificity of the ionic liquid solutions, i.e., for a diversity of distinct solutes differing in chemicalnature.
Subject: Química física, Espectroquímica, Engenharia química
Physical chemistry, Spectrochemistry, Chemical engineering
Scientific areas: Ciências da engenharia e tecnologias::Engenharia química
Engineering and technology::Chemical engineering
Document Type: Artigo em Revista Científica Internacional
Rights: restrictedAccess
Appears in Collections:FCUP - Artigo em Revista Científica Internacional

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