Supported liquid membrane transport of alkali metal cations by monoazacryptand with a partially fluorinated sidearm and the corresponding monoazacrown ethers.

Monoazacryptand [20.18.18] (1), monoaza-15-crown-5 (2a), and monoaza-18-crown-6 (2b) with a partially fluorinated sidearm were newly prepared and their transport abilities were estimated in a supported liquid membrane containing a mixture of 2- (perfluorohexyl) ethyl alcohol and 2- (perfluorooctyl) ethyl alcohol. In competitive passive transport of K+, Na+, and Li+ under neutral conditions, the K+ selectivity increased in the order: ionophore 2a<ionophore 2b<ionophore 1; whereas, the transport velocity increased in the order: ionophore 2a<ionophore 1<ionophore 2b. On the other hand, only ionophore 1 successfully transported K+ in the transport from the neutral source phase to the acidic receiving phase. This result was reasonably explained by considering the excellent K+ complexing ability of monoazacryptand (1) in comparison with that of monoazacrown ethers (2a and 2b).