Complex formation between uranium(VI) and thorium(IV) ions with some α-amino-acids

Abstract

Proton, uranyl, and thorium complex formation of the α-amino-acids (H₂L) serine, cysteine, methionine, threonine, alanine and other substituted glycines with UO₂²⁺ and Th⁴⁺ have been measured potentiometrically at 25 °C and constant ionic strength [I= 0.10 mol dm^–3(KNO₃)]. It was assumed that the complex species [ML] and [ML₂] only were formed. Comparison of the results for alanine and those for serine, cysteine, and methionine suggest only limited bonding between the metal ions and the sulphur atom in cysteine and methionine but somewhat stronger bonding with the oxygen atom in serine.