The response behavior of PPy-DB18C6 electrode to terbium(III) in acetonitrile and its thermodynamic application

Polypyrrole modified electrode prepared by electropolymerization of pyrrole in the presence of a complexing ligand, dibenzo-18-crown-6(DB18C6), was prepared and investigated as a Tb3+-selective electrode in acetonitrile. The potentiometric response of the electrode was linear within the Tb3+ concentration range 1 × 10−5-1 × 10−2 M with a Nernstian slope of 20.9 mV decade−1 in AN. The electrode was applied to study the complexation of the terbium(III) ion in acetonitrile with such other basic aprotic solvent molecules (D) as dimethyl sulfoxide, N,N-dimethyl formamide, propylene carbonate and pyridine. The successive complex formation constant (βi) and Gibbs energies of transfer (ΔGtr) of Tb3+ in AN in relation to such D were obtained.