Complexation thermodynamic of Water-soluble p-sulfonatedCalix[4] arene with Tungsten(VI) in aqueous solution

Spectrophotometric titrations have been performed in aqueous solution at different temperature(25 ± 0.1 to 65 ± 0.1 °C) to calculate the complex formation constants (K) and thermodynamic parameters ( G , H , and T S ) for the stoichiometric 1:1 complexation ofTungsten(VI) with (25, 26, 27, 28, 29- tetrahyroxy-5,11, 17, 23- tetrasulfonic acid calix(4)arene) The complexing ability of p-sulphonato-calix[4]arene towards tungestan has been evaluated at natural pH of p-sulphonato-calix[4]arene (pH = 3.7). Considering the formation constant values, the binding selectivity of the host towards the guest at different temperatures is in the order (25> 35> 45> 55> 65°C ). The effect different temperatures have been evaluated and a roughly linear relationship between Ho and T So has been observed for the studied systems and is discussed.

کلیدواژه ها:

host-guest complex ، p-Sulphonato-calix[4]arene ، Tungsten(VI) ، thermodynamics ، Formation constant