Synthesis, characterization and luminescence property of N, N′-di(pyridine N-oxide-2-yl)pyridine-2,6-dicarboxamide and corresponding lanthanide (III) complexes

• Published in: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Molecular and biomolecular spectroscopy, 2007-02, Vol.66 (2), p.289-294
• Main Authors: Zhang, Hai-Jun, Gou, Ru-Hu, Yan, Lan, Yang, Ru-Dong
• Format: Article
• Language: English
• Subjects: Amides - chemical synthesis; Amides - chemistry; Chelating Agents - chemical synthesis; Chelating Agents - chemistry; Fluorescence; Heterocyclic Compounds, 3-Ring - chemical synthesis; Heterocyclic Compounds, 3-Ring - chemistry; Hydrogen Bonding; Lanthanoid Series Elements - chemistry; Ligands; Molecular Structure; N, N′-Di(pyridine N-oxide-2-yl)pyridine-2,6-dicarboxamide metal complexes; Phosphorescence; Pyridine N-oxide; Rare earth compounds; Spectrometry, Fluorescence
• ISSN: 1386-1425
• DOI: 10.1016/j.saa.2006.02.054

A new ligand, N, N′-di(pyridine N-oxide-2-yl)pyridine-2,6-dicarboxamide (LH 2) and its several lanthanide (III) complexes (La, Eu, Gd, Tb, Y) were synthesized and characterized in detail based on elemental analysis, conductivity measurements, IR, 1H NMR, MS (FAB) and UV spectra and TG-DTA studies. The results indicated that the composition of these binary complexes is [Ln(LH 2)(NO 3) 2·H 2O]NO 3· nH 2O ( n = 0–1); while the ligand has a good planar structure with strong hydrogen bonds. The fluorescence spectra exhibits that the Tb (III) complex and the Eu (III) complex display characteristic metal-centered fluorescence in solid state while ligand fluorescence is completely quenched. However, the Tb (III) complex displays more effective luminescence than the Eu (III) complex, which is attributed to especial effectivity in transferring energy from the lowest triplet energy level of the ligands ( T) onto the excited state ( 5D 4) of Tb (III) than that ( 5D 1) of Eu (III).