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We present a molecular dynamics study of 18C6, 15C5 crown ethers and their acyclic polyether analogues at the water/supercritical-CO 2 interface. The aqueous and CO 2 components form distinct phases, separated by an interface, where in all systems, the ethers are found to concentrate. Simulations of the inclusive K + &18C6 Pic À complexes led to decomplexation of K + and accumulation of the crown ethers on the CO 2 side of the interface, while Pic À anions stack in the aqueous phase. When the K + cations are constrained to form inclusive complexes with 18C6, all complexes concentrate at the interface, be the counterions free to move, or constrained to coordinate to K + . In the presence of nitric acid, modeled by equimolar mixtures of HNO 3 , NO 3À and H 3 O + forms, the ethers remain surface active, as does the neutral form of the acid. These simulations demonstrate the importance of interfacial phenomena in assisted ion extraction to supercritical-CO 2 .

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“…alkaline earth, trivalent lanthanides, actinides) by PEG (polyethylene glycols). [57][58][59][60][61]…”

Section: Discussionmentioning

confidence: 99%

Ethers, crown ethers and 18-crown-6 K⁺complexes at a water/SC-CO₂interface: a molecular dynamics study

Vayssiere

Wipff

2003

Phys. Chem. Chem. Phys.

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“…alkaline-earth, trivalent lanthanides, actinides) by polyethylene glycols. [53][54][55][56][57] While the present study considered about equal volumes of water and CO 2 phases, it would be interesting to also investigate the effect of CO 2 /water ratio, in line with the possible formation of micelles, [58][59][60] especially with perfluorinated '' surfactants ''.…”

Section: Discussionmentioning

confidence: 99%

Importance of counter-ions in alkali and alkaline-earth cation extraction by 18-crown-6: molecular dynamics studies at the water/sc-CO₂interface

Vayssiere

Wipff

2003

Phys. Chem. Chem. Phys.

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We present a molecular dynamics study of concentrated solutions of K + and Sr 2+ cations and their complexes with 18C6 at the water/supercritical-CO 2 interface, and compare picrate '' Pic À '' vs. perfluorooctanoate '' PFO À '' counter-ions at 305 and 350 K. The results allow to understand why K + is poorly extracted in conditions where Sr 2+ is transferred to the supercritical fluid. In all cases, the solutes are found to concentrate near the interface, with interesting differences, depending on the cation, counter-ion and extractant. With the two anions, the SrX 2 salts are surface active, as a result of cation-anion pairing, while the distribution of the K + ions depends on X À . The inclusive K + &18C6 complexes partially decomplex, and decomplexation is more effective at 350 K than at 305 K. The most remarkable result is the extraction of Sr 2+ &18C6,2PFO À complexes in which the anions axially co-complex the cation, while retaining CO 2 -philic interactions via their perfluorinated chain. This Sr 2+ extraction is confirmed by several computational tests which point to the importance of concentration effects and agree with experiment. It contrasts with the formation of an interfacial film with Sr 2+ &18C6,2Pic À complexes, assembled via bridging Pic À Á Á ÁSr 2+ Á Á ÁPic À and stacking Pic À Á Á ÁPic À interactions.

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“…Extraction of actinides such as UO 2 2+ and Pu 4+ using 18-crown-6 and 15-crown-5 in (NH 4 ) 2 SO 4 /PEG (polyethylene glycol) ATPS has been investigated [9][10][11]. A positive correlation has been observed between the crown ether concentration and extraction of actinides, especially using 18-crown-6.…”

Section: Introductionmentioning

confidence: 99%

Enhanced Extraction of Amino Compounds Using Dicyclohexyl-18-crown-6 as a Ligand in an Aqueous Two-phase System

Kai

Oshima

Baba

2010

SERDJ

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Various studies on the complexation between crown ethers and biomolecules bearing primary amino groups have been conducted. In the present study, extraction of amino compounds based on the complexation with a crown ether in Li 2 SO 4 /PEG aqueous two-phase system has been examined. In the series of crown ethers and their analogues, only dicyclohexano-18-crown-6 (DCH18C6) functioned as a ligand for enhancing the extraction of amino compounds into the PEG-rich phase. The number of primary amino groups of the guest molecules as well as their hydrophobicity is dominant for enhancing the extraction based on the complexation with DCH18C6. From the results of slope analysis, the number of DCH18C6 molecules complexing with an amino compound agreed with the number of primary amino groups.

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Cited by 9 publications

References 5 publications

Ethers, crown ethers and 18-crown-6 K⁺complexes at a water/SC-CO₂interface: a molecular dynamics study

Ethers, crown ethers and 18-crown-6 K⁺complexes at a water/SC-CO₂interface: a molecular dynamics study

Importance of counter-ions in alkali and alkaline-earth cation extraction by 18-crown-6: molecular dynamics studies at the water/sc-CO₂interface

Enhanced Extraction of Amino Compounds Using Dicyclohexyl-18-crown-6 as a Ligand in an Aqueous Two-phase System

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Cited by 9 publications

References 5 publications

Ethers, crown ethers and 18-crown-6 K+complexes at a water/SC-CO2interface: a molecular dynamics study

Ethers, crown ethers and 18-crown-6 K+complexes at a water/SC-CO2interface: a molecular dynamics study

Importance of counter-ions in alkali and alkaline-earth cation extraction by 18-crown-6: molecular dynamics studies at the water/sc-CO2interface

Enhanced Extraction of Amino Compounds Using Dicyclohexyl-18-crown-6 as a Ligand in an Aqueous Two-phase System

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Ethers, crown ethers and 18-crown-6 K⁺complexes at a water/SC-CO₂interface: a molecular dynamics study

Ethers, crown ethers and 18-crown-6 K⁺complexes at a water/SC-CO₂interface: a molecular dynamics study

Importance of counter-ions in alkali and alkaline-earth cation extraction by 18-crown-6: molecular dynamics studies at the water/sc-CO₂interface