STUDY OF CATION TRANSFER ACROSS THE WATER NITROBENZENE INTERFACE FACILITATED BY A SYNTHETIC NEUTRAL DICARBOXAMIDE/

The transfer of proton, alkali, and alkaline earth metal ions across t he water/nitrobenzene interface, facilitated by a synthetic neutral di carboxamide ionophore in the nitrobenzene phase was investigated using cyclic voltammetry. The ionophore-facilitated transfer of Li+ Ca2+, a nd Ba2+ ions showed cathodic current peaks, and the transfer of H+ ion s apparently resulted in peaks of both anodic and cathodic currents wi thin the potential window. The transfer process of these ions was foun d to be controlled by the diffusion of the ionophore in the nitrobenze ne. The formation of a 1:1 complex for H+ and of 1:2 (cation to ionoph ore) complexes for Li+, Ca2+, and Ba2+ ions was inferred, through peak separation or the dependence of the cathodic peak potential on the lo garithm of the ionophore concentration, to be involved in the transfer process. The equilibrium constants K-Li,K-M for the exchange reaction of the ion M(Z+) with the Li-(+)ionophore complex at the water/nitrob enzene interface were evaluated and correlated with the potentiometric selectivity coefficients K-Li,M(Pot).