Reactions of Lanthanide Ions with Glycolic Acid or Tartaric Acid in the Presence of Spermine: Potentiometric and Spectroscopic Studies

In order to determine how lanthanide ions (La, Nd, Eu, Gd, Ho, Tb, Lu) coordinate in ternary systems with alpha-hydroxy acids (glycolic acid-GA; or tartaric acid-Tar) and spermine (Spm), potentiometric studies were conducted. In addition, binary systems of metal ions with alpha-hydroxy acids were studied, as well as the possibility of non-covalent interactions between the studied ligands. This study was carried out in aqueous solutions, and the composition of the formed complexes was confirmed using computer data analysis. Using spectroscopic measurements, the inner and outer coordination spheres of the central metal ion were determined. In ternary systems, via luminescent studies, the occurrence of the so-called 'antenna effect' was confirmed. These studies confirmed the formation of ternary complexes in which spermine can exist in the outer coordination sphere of lanthanide ions interacting non-covalently with an alpha-hydroxy acid in the inner coordination sphere.