Demixing of binary water-chloroform mixtures containing ionophoric solutesand ion recognition at a liquid-liquid interface: A molecular dynamics study

Citation
N. Muzet et al., Demixing of binary water-chloroform mixtures containing ionophoric solutesand ion recognition at a liquid-liquid interface: A molecular dynamics study, J PHYS CH B, 102(52), 1998, pp. 10772-10788
Citations number
92
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
JOURNAL OF PHYSICAL CHEMISTRY B
ISSN journal
15206106 → ACNP
Volume
102
Issue
52
Year of publication
1998
Pages
10772 - 10788
Database
ISI
SICI code
1520-6106(199812)102:52<10772:DOBWMC>2.0.ZU;2-J
Abstract
We report a series of molecular dynamics simulations on the demixing of "ho mogeneous" binary water-chloroform mixtures containing species involved in the assisted ion extraction process. We consider an ionophore: L (L = 1,3-a lternate calix4arene-crown6), uncomplexed salts of Cs+ and the LCs+ and LNa + cation complexes with a lipophilic (Pic(-)) and a hydrophilic (Cl-) count erion, respectively, as being solutes. In all cases, the liquids separate r apidly, leading to two solvent slabs separated by a well-defined interface. However, the final state is very different, depending on the hydrophilic/h ydrophobic balance of the solutes: the Cs+ and NO3- ions of the CsNO3 salt are completely immersed in the aqueous phase, whereas Pic(-) anions display a strong adsorption at the interface. The LCs+ complex and the free ligand L, although more soluble in the organic phase than in water, also display a surfactant like behavior. Similar conclusions are obtained when L, LCs+, Cs+ Pic(-), and Cs+ NO3- ions are simultaneously present in the solution. O n the basis of free energy perturbation calculations on LM+ complexes, we c alculate a marked Cs+/Na+ recognition by L at the interface. These results have important implications concerning the mechanism of ionophore assisted liquid-liquid ion extraction and recognition processes at the interface.