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Water soluble calix[4]arenes. A thermodynamic investigation of proton complex formation

1992; Taylor & Francis; Volume: 1; Issue: 1 Linguagem: Inglês

10.1080/10610279208027437

1061-0278

Giuseppe Arena, R. CALI, Gaetano G. Lombardo, Enrico Rizzarelli, Domenico Sciotto, Rocco Ungaro, Alessandro Casnati,

Supramolecular Chemistry and Complexes

Abstract Thermodynamic parameters of protonation of calix[4]arene-p-tetra sulphonate were potentiometrically and calorimetrically determined in aqueous solution at 25 °C and I = 0.1 mol dm−3 (NaNO3). These values were compared with literature findings. ΔH° and ΔS° values reveal that the penta-anion protonation is energetically costly. In this connection the role played by hydrogen bonding and the cone conformation stabilization are critically discussed. Proton formation constants of the calix[4]arene-p-tetrasulphonate-tetra-carboxylate derivative in the cone conformation were also potentiometrically determined under the same experimental conditions.