Ionselective Electrodes Based on Adamantylthiacalix[4]arenes for Alkali Cations Determination

The possibility of using three derivatives of p-R-thiacalix[4]arene: tetraethyl ester of p-(1-adamantyl)thiacalix[4]arene acid (I) and asymmetric p-tert-buthylcalix[4]-p-R-thiacalix[4]arene “molecular tubes” [R = tert-Bu(II), 1-adamantyl(III)] as ionophores in PVC-membrane ISEs for the determination of Na+, K+ and Rb+ ions was studied. It was found that an electrode based on thiacalix[4]arene (I) exhibited high selectivity toward Na+ ions, and electrodes with (II) and (III) demonstrated a good potentiometric response of the Rb+ ion; Rb+ can be determined in the presence of excess amounts Na+ and K+.