Toward an understanding of the aqueous solubility of amino acids in the presence of salts : a molecular dynamics simulation study

Ion-specific effects on the aqueous solubilities of biomolecules are relevant in many areas of biochemistry and life sciences. However, a general and well-supported molecular picture of the phenomena has not yet been established. In order to contribute to the understanding of the molecular-level interactions governing the behavior of biocompounds in aqueous saline environments, classical molecular dynamics simulations were performed for aqueous solutions of four amino acids (alanine, valine, isoleucine, and 2-aminodecanoic acid), taken as model systems, in the presence of a series of inorganic salts. The MD results reported here provide support for a molecular picture of the salting-in/salting-out mechanism based on the presence/absence of interactions between the anions and the nonpolar moieties of the amino acids. These results are in good qualitative agreement with experimental solubilities and allow for a theoretical interpretation of the available data

Characterization of systems of thiophene and benzene with ionic liquids

The potential of ionic liquids for aromatic-aliphatic separation or removal of sulfur-containing compounds such as thiophene is well established but, in spite of a number of phase diagrams reported in the literature, the values of other properties required for process design, such as viscosities and densities, are poorly characterized for these mixtures. In this work, systems presenting a LLE with a LCST are studied. Experimental density and viscosity data for binary systems of benzene with [C(4)C(1)im][SCN], [C(4)D(1)im][CF3SO3] and [C(2)C(1)im][NTf2], and thiophene with [C(4)C(1)im][SCN] and [C(4)C(1)im][NTf2] are presented. Additionally, the liquid-liquid phase diagram for the binary system of thiophene with [C(4)C(1)im][NTf2] is also reported. The excess molar volumes and viscosity deviations were further estimated and correlated and their values discussed. (C) 2013 Elsevier B.V. All rights reserved

\"Washing-out\" ionic liquids from polyethylene glycol to form aqueous biphasic systems

The molecular-level mechanisms behind the formation of aqueous biphasic systems (ABS) composed of ionic liquids (ILs) and polymers are hitherto not completely understood. For the first time, it is herein shown that polymer-IL-based ABS are a result of a ``washing-out'' phenomenon, and not of a salting-out effect of the IL over the polymer as assumed in the past few years. Novel evidence is herein provided by experimental results combined with molecular dynamics (MD) simulations and density functional theory (DFT) calculations