ELECTROCHEMICAL AND SPECTROFLUOROMETRIC BEHAVIORS OF EU(III) COMPLEXES IN AQUEOUS-SOLUTION

Eu(III) exhibits one electron-transfer reduction at E1/2 = -0.617 V vs . Ag/AgCl and the hypersensitive peak at 618 nm corresponding to 5D0-- >7F2 transition in 0.10 M LiClO4 aqueous solutions. Upon the addition of carboxylate or sulfonate anions to the Eu(III) aqueous solutions, t he reduction potential shifts negatively and the reduction current dec reases because of the complex formation between Eu(III) ions and the a nions. However, for the case of carboxylate anion (acetate or propiona te) the shift of reduction peak potential and the emission intensity a t 618 nm are greater. The results are interpreted in terms of the diff erences in the formation constants and the hypersensitivity.