Ion-transfer voltammetry at a supported fluorous liquid membrane | water interface

Ion-transfer reactions at the supported fluorous liquid membrane (SFLM) | water (W) interface were examined using cyclic voltammetry. The SFLM was constructed by impregnating a polytetrafluoroethylene or polyvinylidene fluoride microporous filter with a fluorous solvent, 1H,1H,5H-octafluoropentyl-1,1,2,2-tetrafluoroethyl ether (OFE). Various ions, including tetraphenylarsonium and tetraphenylborate, exhibited nearly reversible voltammetric waves for the ion-transfer reaction at the SFLM | W interface, enabling the determination of formal ion-transfer potentials. The formal Gibbs transfer energies calculated from these potentials were in good agreement with those determined from the conventional OFE | W interface, particularly when the polytetrafluoroethylene membrane was used. This indicates that the fluorophilic property of OFE was maintained in the SFLM. The supported liquid membrane is an effective means of providing a liquid | liquid interface with mechanical stability and ease of handling. Additionally, it enables a marked reduction in the volume of the expensive fluorous solvent required for electrochemical measurements. Therefore, the SFLM system is advantageous for liquid | liquid electrochemical studies and applications using fluorous solvents.