Abstract: ¹H and ¹³C NMR techniques were used to study complexation of lanthanide ions with Gly-Ala in aqueous solution. For Yb complex with Gly-Ala the stability constant was calculated from the concentration dependence of lanthanide-induced shifts. ¹³C shifts induced by heavy lanthanide ions Dy³⁺, Ho³⁺, Er³⁺, Tm³⁺ and Yb³⁺ were analyzed by Reuben's method. The simulation for ligand conformation of lanthanide complex with Gly-Ala shows that the ligand segment C1-C2-N-C3 is in gauche form,while the segments C2-N-C3-C4 and C5-C2-N-C3 in trans form. The effects of side-group size of several glyeine-eontaining dipeptides on complex stability constants, ligand conformations and structure of complexes in solution were discussed.

Key words: glycyl-alanine, lanthanide-indueed shift, NMR