EFFECT OF SUCCESSIVE COMPLEX FORMATION ON THE FACILITATED ION TRANSFER ACROSS THE OIL/WATER INTERFACE TRANSFER OF Ba2+ ION FACILITATED BY DIBENZO-18-CROWN-6

Transfer of Ba2+ ion facilitated by dibenzo-18-crown-6(DB18C6) has been studied at the nitrobenzene(NB)/water(WA,interface by using cyclic voltammetry. When the concentratAn of Ba2+ in W((W)c(Ba)) is much higher than that of DB18C6 in NB((NB)c(DB18C6)), the cyclic voltammograms reveal typical reversible wave of ion tgansfer R << Aused by forming 1:1 (metal to ligand) complex in NB. When (W)c(Ba) << (NB)c(DB18C6), the dominant species carrying the current across the interface is 1:2(metal to ligand) complex. The stability of 1:1 and 1:2 complex in NB are log(10)K(1)=9.6 and NB log(10)K(2)= 2.4, where K-1=[ML]/[M][L] and K-2=[ML2]/[ML][L] When cip8C1 < 0.5 mM' the t A distortion of the cyclic voltammograms due IR e :2 complex formation is small but becomes significant when (NB)c(DB18C6) > 1 mM