Liquid-Liquid Extraction of Alkali Cations by Calix[4]Crown Ionophores: Conformation and Solvent Dependent Na+/Cs+ Binding Selectivity. A MD FEP Study in Pure Chloroform and MD Simulations at the Water/Chloroform Interface

Lauterbach, M.; Wipff, Georges

doi:10.1007/978-94-009-0317-3_6

Cited by 13 publications

(4 citation statements)

References 63 publications

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“…After 400 ps the two liquid phases were separated by a “flat” interface, where L Cs + or L Na + adsorbed on the chloroform side, while the Pic - anion was “right at the border”. The final situation of L Cs + Pic - was nearly identical to the one obtained from simulations which started from the two adjacent liquid phases, , indicating that it indeed corresponds to a thermodynamic equilibrium . The Pic - anion displayed different relationships with the complex: it was separated from L Cs + , but in loose contact with L Na + .…”

Section: Resultssupporting

confidence: 56%

“…The interactions between atoms separated by at least three bonds were described by a pairwise additive 1−6−12 potential. Parameters for the solutes were taken from the AMBER force field and from previous studies of these molecules in pure homogeneous solvents. , The atomic charges on L 13,14 and on the Pic - anion were derived from electrostatic potentials. The Na + to Cs + alkali cations were described by the Åqvist parameters .…”

Section: Methodsmentioning

confidence: 99%

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Demixing of Binary Water−Chloroform Mixtures Containing Ionophoric Solutes and Ion Recognition at a Liquid−Liquid Interface: A Molecular Dynamics Study

1998

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We report a series of molecular dynamics simulations on the demixing of “homogeneous” binary water−chloroform mixtures containing species involved in the assisted ion extraction process. We consider an ionophore L (L = 1,3-alternate calix4arene-crown6), uncomplexed salts of Cs+ and the LCs+ and LNa+ cation complexes with a lipophilic (Pic-) and a hydrophilic (Cl-) counterion, respectively, as being solutes. In all cases, the liquids separate rapidly, leading to two solvent slabs separated by a well-defined interface. However, the final state is very different, depending on the hydrophilic/hydrophobic 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. On the basis of free energy perturbation calculations on LM+ complexes, we calculate 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.

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Section: Resultssupporting

confidence: 56%

Section: Methodsmentioning

confidence: 99%

Demixing of Binary Water−Chloroform Mixtures Containing Ionophoric Solutes and Ion Recognition at a Liquid−Liquid Interface: A Molecular Dynamics Study

1998

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“…Cs + /Na + extraction by calixarenes [28], uranyl extraction by CMPO [39] or TBP [37], Sr 2 + extraction by 18-crown-6 [32] or calixarenes [40]) with different counterions (e.g. Cl − /NO 3 − / Pic − ) [28,38,41]. Phospholipids [42], quaternary ammonium cations [35,36], guanidinium + , AsPh 4 + or BPh 4…”

Section: Introductionmentioning

confidence: 99%

Distribution of hydrophilic, amphiphilic and hydrophobic ions at a liquid/liquid interface: a molecular dynamics investigation

Berny

Schurhammer

Wipff

2000

Inorganica Chimica Acta

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We report molecular dynamics studies on the interfacial distribution of ionic species of different size, shape and topology at a water/chloroform interface: hydrophilic K + Cl − , K + SCN − and K + Pic − ions, amphiphilic ammonium NTMA + cations and farnesylphosphate FPH − anions, tetrahedral hydrophobic AsPh 4 + and BPh 4 − ions, with different counterions. Contrasted distributions are observed. The K + Cl − and K + SCN − ions sit almost exclusively in the water phase, but SCN − is less 'repelled' than Cl − by the interface. The Pic − anions are partly adsorbed at the interface and dissolved in the water phase where they display remarkable p-stacking interactions. Amphiphilic NTMA + cations or FPH − anions adsorb and dilute at the interface. Less expected is the high surface activity of symmetrical AsPh 4 + and BPh 4 − ions, with marked counterion effects. The two ions fully adsorb at the interface in the AsPh 4 + BPh 4 − salt, while in the Na + BPh 4 − or AsPh 4 + Cl − salts, they display an equilibrium between the organic phase and the interface. Crossed comparisons between the different solutions reveal the important role of counterions on the distribution of a given ionic species. These results are discussed in relation to experimental data.

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“…Recently, interesting compounds combining both structural motives, i.e. having variously modified crowns attached to calixarenes, have been prepared and studied. − As in the previous simpler cases, the structure can be tailored to selectively bind a narrow spectrum of ions or even one kind of cation according to its size. This makes such compounds practically attractive e.g.…”

Section: Introductionmentioning

confidence: 99%

Interaction of Cesium Ions with Calix[4]arene-bis(t-octylbenzo-18-crown-6): NMR and Theoretical Study

et al. 2011

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Using (1)H, (13)C, and (133)Cs NMR spectra, it is shown that calix[4]arene-bis(t-octylbenzo-18-crown-6) (L) forms complexes with one (L·Cs(+)) and two (L·2Cs(+)) Cs(+) ions offered by cesium bis(1,2-dicarbollide) cobaltate (CsDCC) in nitrobenzene-d(5). The ions interact with all six oxygen atoms in the crown-ether ring and the π electrons of the calixarene aromatic moieties. According to extraction technique, the stability constant of the first complex is log β(nb)(L·Cs(+)) = 8.8 ± 0.1. According to (133)Cs NMR spectra, the value of the equilibrium constant of the second complex is log K(nb)((2))(L·2Cs(+)) = 6.3 ± 0.2, i.e., its stabilization constant is log β(nb)(L·2Cs(+)) = 15.1 ± 0.3. Self-diffusion measurements by (1)H pulsed-field gradient (PFG) NMR combined with density functional theory (DFT) calculations suggest that one DCC(–) ion is tightly associated with L·Cs(+), decreasing its positive charge and consequently stabilizing the second complex, L·2Cs(+). Using a saturation-transfer (133)Cs NMR technique, the correlation times τ(ex) of chemical exchange between L·Cs(+) and L·2Cs(+) as well as between L·2Cs(+) and free Cs(+) ions were determined as 33.6 and 29.2 ms, respectively.

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Liquid-Liquid Extraction of Alkali Cations by Calix[4]Crown Ionophores: Conformation and Solvent Dependent Na+/Cs+ Binding Selectivity. A MD FEP Study in Pure Chloroform and MD Simulations at the Water/Chloroform Interface

Cited by 13 publications

References 63 publications

Demixing of Binary Water−Chloroform Mixtures Containing Ionophoric Solutes and Ion Recognition at a Liquid−Liquid Interface: A Molecular Dynamics Study

Demixing of Binary Water−Chloroform Mixtures Containing Ionophoric Solutes and Ion Recognition at a Liquid−Liquid Interface: A Molecular Dynamics Study

Distribution of hydrophilic, amphiphilic and hydrophobic ions at a liquid/liquid interface: a molecular dynamics investigation

Interaction of Cesium Ions with Calix[4]arene-bis(t-octylbenzo-18-crown-6): NMR and Theoretical Study

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