Liquid Membrane Transport of Alkali Metal Cations by Cooperative Carriers Composed of Calixa r e ne and Alkanoic Acid

Abstract

Calix[n]arene derivatives (n=4, 6 and 8) and alkanoic acids were studied as carriers to examine the passive and competitive transport of alkali metal cations in the chloroform membrane system. Calixarene derivatives did not transport any cation by themselves, except proton ionizable ones, which selectively transported Cs₊ as reported previously. The mixture with alkanoic acid, however, mediated the transport effectively, so that they acted as carriers cooperatively in this system. In the presence of dodecanoic acid almost all the neutral calixarenes transported Li₊ efficiently and selectively.2-Bromododecanoic acid was more effective than dodecanoic acid on the transport rate in all systems. Structural effects on the transport abilities of th e cooperative carriers are discussed on the basis of the results.