Journal of Inclusion Phenomena and Macrocyclic Chemistry

, Volume 58, Issue 1, pp 181-186

First online:

Conductance Study of the Thermodynamics of Complexation of K+, Rb+, Cs+ and Tl+ Ions with Dibenzo-24-crown-8 in Binary Acetonitrile–Nitromethane Mixtures

  • Mehdi TaghdiriAffiliated withDepartment of Chemistry, Tarbiat Moallem University
  • , Mohammad Kazem RofoueiAffiliated withDepartment of Chemistry, Tarbiat Moallem University
  • , Mojtaba ShamsipurAffiliated withDepartment of Chemistry, Razi University Email author 

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The complexation reactions between dibenzo-24-crown-8 (DB24C8) and K+, Rb+, Cs+ and Tl+ ions were studied conductometrically in different acetonitrile–nitromethane mixtures at various temperatures. The formation constants of the resulting 1:1 complexes were calculated from the computer fitting of the molar conductance–mole ratio data at different temperatures. At 25 °C and in all solvent mixtures used, the stability of the resulting complexes varied in the order Tl> K> Rb> Cs+. The enthalpy and entropy changes of the complexation reactions were evaluated from the temperature dependence of formation constants. It was found that the stability of the resulting complexes increased with increasing nitromethane in the solvent mixture. The TΔS° vs. ΔH° plot of all thermodynamic data obtained shows a fairly good linear correlation indicating the existence of enthalpy–entropy compensation in the complexation reactions.


conductance dibenzo-24-crown-8 enthalpy–entropy compensation K+, Rb+, Cs+ and Tl+ complexes mixed solvent stability