Luminescent properties of Eu (III) complexes with carboxylate ligands and their light conversion films

This study reports the synthesis and characterization of four europium (III) complexes with different carboxylate ligands, namely 2-pyridine-acrylic acid (H2-PA), 2-pyridine-carboxylic acid (HPic), benzoic acid (HBen), and cinnamic acid (HCin), as well as a binuclear europium-lanthanum complex with HCin as the only ligand. The obtained complexes and the light conversion films prepared from them were extensively characterized by various techniques, including elemental analysis, infrared spectroscopy (IR), X-ray single crystal diffraction, thermogravimetric analysis (TGA), and fluorescence spectroscopy. Efforts were made to systemically investigate the structural, coordination, photophysical, and thermal properties of the luminescent materials, and elucidate the correlations between the ligand triplet energy levels and the luminescent properties of the complexes. The results reveal that the introduction of LaIII cannot only enhance the luminescent intensity of the light conversion agent and corresponding film, but also have obvious effect on enhancing the ultraviolet aging resistance of the light conversion film. Moreover, the proper doping concentration (0.5%) of the EuIII complex La-Eu-Cin in film may better balance the properties and cost.