Conductance and Thermodynamic Study of the Complexation of Ethyl p-Tert-butylcalix[4]arene Tetraacetate with Alkali Metal and Silver Ions in Various Solvents

The first conductometric studies for the complexation reactions between alkali metaland silver cations with ethyl p-tert-butylcalix[4]ester in the cone conformation using acetonitrile and methanol in the temperature range 278–303 K are reported. The observed molar conductivities Λ were found to decrease significantly for mole ratios less than unity. The conductivity data were analysed using a computer program based upon 1 : 1 stoichiometry. Stability constants of the resulting 1 : 1 complexes were determined, indicating that the sequence of stability in acetonitrile is Na+ > Li+ > K+. The Δ H0 and Δ S0 values of the calix[4]ester complexation reactions were determined from the temperature dependence of the complexation constants, and their significance are discussed.