Article Dans Une Revue Russian Chemical Bulletin Année : 2004

Accumulation of host-guest ion complexes with different counterions at the water-supercritical CO2 interface: a molecular dynamics study

Alain Chaumont
Nicolas Galand
  • Fonction : Auteur
Philippe Vayssiere
  • Fonction : Auteur
Georges Wipff
  • Fonction : Auteur
  • PersonId : 831375
  • IdRef : 060790970

Résumé

The behavior of ion complexes at the water-supercritical carbon dioxide interface was considered by molecular dynamics simulations. The following complexes were studied: Cs(+)subset ofcalix [4] crown -6, K(+)subset of222 cryptate with chloride or dicarbollide (CCD-) counterions, the Sr(2+)subset of18C6 complex with the picrate (Pic-) or perfluorooctanoate (PFO-) counterions, and the Cl(-)subset ofTet(4+) complex with chloride counterions (Tet(4+) is a tetrahedral tetraammonium cation). The simulations demonstrate the analogy between aqueous interfaces with organic immiscible liquids and the CO(2) phase. Water and supercritical CO(2) are poorly miscible and form an interface. Most of the complexes are accumulated at the interface, instead of diffusing into the organic phase in which they should be more soluble. In addition, marked counterion effects are observed. The CCD-, Pic-, and PFO- anions are surface active and are concentrated at the interface, but show different relationships with the complexes. The formation of ion pairs is precluded by the very hydrophobic CCD- anions, which promote the extraction of cryptates as separated ion pairs to the CO(2) phase. Conversely, the extraction of the Sr(2+) ions with 18C6 proceeds via a co-complexation mechanism, including the formation of the Srsubset of18C6(PFO)(2), complex having a CO(2) affinity. The mechanism of assisted ion transfer to the CO(2) phase is discussed.

Fichier non déposé

Dates et versions

hal-02977101 , version 1 (23-10-2020)

Identifiants

  • HAL Id : hal-02977101 , version 1

Citer

Alain Chaumont, Nicolas Galand, Rachel Schurhammer, Philippe Vayssiere, Georges Wipff. Accumulation of host-guest ion complexes with different counterions at the water-supercritical CO2 interface: a molecular dynamics study. Russian Chemical Bulletin, 2004, 53 (7), pp.1459-1465. ⟨hal-02977101⟩
69 Consultations
0 Téléchargements

Partager

  • More