Étude par spectroscopie d'absorption de la complexation des lanthanides trivalents par les acides amino-carboxyliques

An absorption spectrophotometric study of the complexation of trivalent lanthanides by aminocarboxylic acidsComplexation of the lanthanides by aminoacetic acids shows a shift in some absorption bands of the cation towards higher wavelengths. By choosing the medium —pH and concentrations —adequately, each complex species can be characterized by a certain shift. This study has been carried out at 20°C in M KCl and concerns the 1:1, 1:2, 1:3 and mixed complexes of praseodymium, holmium and thulium with G, NTA, HEDTA, EDTA, DCTA and DTPA. The characteristic shifts are correlated with the number of coordinating sites of the chelating agents. It seems that a significant change occurs in the structure of the complex when the number of coordinating sites exceeds nine for the cerium rare earths or eight for the yttrium elements.