ELECTRONS AND IONS MOVING ACROSS LIQUID MEMBRANES

Oxidation and reduction reactions can be carried out by interfacing th e aqueous solution containing the reducing agent and the aqueous solut ion containing the oxidizing agent by a layer of a water immiscible so lvent (e.g. CH2Cl2, the liquid membrane): in the membrane a lipophilic redox system C has to be present, which transports electrons from the aqueous reducing phase to the aqueous oxidizing phase and, in its oxi dized form C+, X- anions in the opposite direction. Metal complexes ha ve been tested as carriers for the transport of electrons across liqui d membranes. In particular, transition metal complexes of lipophilic v ersions of cyclam and 2,2'-bipyridine have been investigated. The thre e-phase redox processes can be controlled by varying the potential of the C/C+ couple in the CH2Cl2 solution. Further selectivity effects de rive from the kinetics of the electron transfer process at the membran e/aqueous phase interface. The possibility to perform light driven ele ctron transport processes mediated by a metal centred carrier is discu ssed.