Gibbs energies of transfer of chiral anions across the interface waterchiral organic solvent determined with the help of three-phase electrodes

摘要

For the first time the differences in free energies have been experimentally determined forudthe solvation of two enantiomeric ions in two enantiomeric solvents. Three-phaseudelectrodes consisting of a droplet of a solution of decamethylferrocene in a chiral solventud(D- and L-2-octanol) attached to a graphite electrode and immersed in an aqueous solutionudcontaining chiral anions, allow the measurement of these data for the transfer of theudenantiomeric ions across the water|chiral solvent interface. In all studied combinations theudGibbs energy to transfer an L-ion from water to the L-solvent was equal to the Gibbsudenergy of transfer of the D-ion from water to the D-solvent, and the same was found forudthe transfer of a L-ion from water to the D-solvent and for the D-ion from water to theudL-solvent. In all cases, the combinations D-anion/D-solvent and L-anion/L-solvent haveudsmaller standard Gibbs energies than the combinations D-anion/L-solvent and L-anion/udD-solvent. This can be explained by less favourable interactions between an anion and audsolvent molecule in the latter cases.