Electrochemical oxidation of <Emphasis Type="Italic">p</Emphasis>-sulfonated calix[8]arene

The water-soluble p-sulfonated sodium salt of calix8]arene (III) was synthesized. The product was characterized by FT-IR, NMR and UV–Vis spectra.Then the electrochemical behaviors of p-sulfonated sodium salt of calix8]arene in NaAc+HAc (pH = 4) buffer solution was studied. In aqueous solution, p-sulfonated calix8]arene can be oxidized when the potential is more than 0.7 V vs SCE. It was confirmed that the reaction was a two-electron irreversible electrochemical reaction. The transfer coefficient, α, was measured as 0.7. At 25°, the diffusion coefficient of p-sulfonated calix8]arene was determined as 8.6 × 10⁻⁷ cm² s⁻¹. The diffusion activation energy of p-sulfonated calix8]arene was 18.9 kJ mol⁻¹ at pH = 4.