Facilitated transfer of alkali metal ions by a tetraester derivative of thiacalix[4]arene at the liquid-liquid interface

The facilitated transfer of alkali metal ions (Na+, K+, Rb+, and Cs+) by 25,26,27,28-tetraetboxycarbonylmethoxy-thiacalix[4]arene across the water/1,2-dichloroethane interface was investigated by cyclic voltammetry. The dependence of the half-wave transfer potential on the metal and ligand concentrations was used to formulate the stoichiometric ratio and to evaluate the association constants of the complexes formed between ionophore and metal ions. While the facilitated transfer of Li+ ion was not observed across the water/1,2-dichloroethane interface, the facilitated transfers were observed by formation of 1: 1 (metal: ionophore) complex for Na+, K+, and Rb+ ions except for Cs+ ion. In the case of Cs+ a 1:2 (metal: ionophore) complex was obtained from its special electrochemical response to the variation of ligand concentrations in the organic phase. The logarithms of the complex association constants, for facilitated transfer of Na+, K+, Rb+, and Cs+, were estimated as 6.52, 7.75, 7.91 (log beta(1)degrees), and 8.36 (log V), respectively.