Cesium-Selective Chemical Modified Field Effect Transistors with Calix[4]arene-crown-6 Derivatives

Calix[4]arene-crown-6 derivatives (1-3) in the 1,3-alternate conformation, incorporated in poly(vinylchloride) membranes of CHEMFETs, exhibit good Cs+-selectivity and Nernstian behaviour. The Cs+-selectivity over Na+, i.e., log K-Cs,Na(pot) = -3.3, is slightly better than observed for bis(18-crown-6) derivatives (log K-Cs,Na(pot) = -3.0). The CHEMFETs respond sub-Nernstian in the presence of NH4+: and K+. Model calculations show that this can be explained by the small difference between the stability constants of the Cs+- and K+-complexes and by the high partition coefficient of NH4+ in favour of the membrane phase, respectively.