Thermodynamic study of dioxovanadium (V) Complexes with p-sulphonato-calix [6] arene in aqueous solution

The complexive ability of p-sulphonato-calix[6]arene towards dioxovanadium(V) has been evaluated in acidic aqueous solution (pH 1.7) using UV–Vis spectrophotometric technique. The result showed that the ligand is capable to complex with the oxo-cations by 1:1 cation to ligand ratios. Formation constant of the system has been determined at different temperatures (25 to 40°C). Considering the formation constant values, the binding selectivity of the ligand towards the oxo-cations at 25 °C is in the order VO2+. The thermodynamic parameters have evaluated and are interpreted in terms of the importance of the various interactions responsible for the complexation. A roughly linear relationship between delta Ho and T delta So has been observed for the studied systems and those were reported in the literature. Finally, the host and guest desolvation involved in the complexation processes are discussed. In conclusion, this study demonstrated the efficiency of the calixarene emulsion, which can be regarded as a promising treatment for dioxovanadium cutaneous contamination.