TRANSDUCTION OF SELECTIVE RECOGNITION BY PREORGANIZED IONOPHORES - K-DIETHOXYCALIX[4]ARENE CROWN-ETHER CONFORMERS( SELECTIVITY OF THE DIFFERENT 1,3)

Three different conformers of 1,3-diethoxy-p-tert-butylcalix[4]arene c rown ethers have been used to study the effect of the ionophore preorg anization on the potentiometric K+-selectivity. Selectivities were mea sured for chemically modified field effect transistors (CHEMFETs) and membrane ion-selective electrodes (ISEs) by two different methods. The ionophores show decreasing K+/Na+ selectivities in the order: partial cone > 1,3-alternate > cone. As a function of time the cone conformer maintained a constant selectivity whereas a continuous decrease of th e selectivity values was observed for the other two conformers. This s upports our prediction based on the association constants and our prev ious H-1 NMR studies on conformational stability.