Synthesis, crystal structures and luminescence properties of europium and terbium picolinamide complexes

Abstract

Abstract The novel coordination structures of europium and terbium chloride-picolinamide complexes (EuCl3·(C6H6N2O)2·5H2O, Eu-pa and TbCl3·(C6H6N2O)2·5H2O, Tb-pa) are reported. The crystal structures in the solid state are characterized by X-ray single crystal diffraction, FTIR, Raman, FIR, THz and luminescence spectroscopy. In the crystal structures, the pyridyl nitrogen and carbonyl oxygen atoms in picolinamide are coordinated to the metal ions to form a five-membered ring structure. The experimental results indicate the similar coordination structures of Eu and Tb-pa complexes and the changes of hydrogen bonds and conformation of the ligands induced by complexation. The results provide models for the coordination structures of lanthanide ions with ligands having amide groups.