Salt-Bridge Supported Bilayer Lipid Membrane Modified with Calix[n]arenes as Alkali Cation Sensors

ABSTRACT Potentiometric behaviors of a salt-bridge supported bilayer lipid membrane (Sb-BLM) modified with Calix[n]arene (n=4, 6, 8) derivatives are described for some alkali metal ions. The modified Sb-BLM was used as an alkali cation sensor. The membrane potentials were observed to generate Nernstian responses to the concentration of alkali metal ions in electrolyte. The Sb-BLM modified with the calix[n]arenes show high selectivity for individual alkali metal ions: Calix[8]arenes for K+, calix[6]arenes for Cs+ Calix[4]arenes show no selectivity for any alkali ions. The interacting mechanism is also discussed.