Synthesis of α-amino acid derived (1,2,3-triazol-4-yl)-picolinamide (tzpa) ligands and their corresponding luminescent Tb(iii) complexes†

The synthesis of chiral α-amino acid derived (1,2,3-triazol-4-yl)-picolinamide (tzpa) ligands 4–6 designed by combining the coordination properties of two well-known ligand structures within a single unit is described. The self-assembly formation between these ligands and the lanthanide ion Tb(iii) was investigated in solution by probing the ground and the singlet excited state properties of the ligands as well as monitoring the evolution of the Tb(iii) emission at long wavelengths. The spectroscopic results showed that while under thermodynamic control the 1 : 3 (Tb : L) is produced, then analysis of the titration data using non-liner regression analysis demonstrated that the main species in solution is the 1 : 2 (Tb : L) after the addition of 0.5 equivalents of Tb(iii).