铽与苯甲酸及其衍生物配合物的合成与发光特性

Syntheses and Fluorescence Properties of Terbium with Benzoic Acid and Its Derivatives

合成了铽与苯甲酸及其衍生物(苯甲酸、邻苯二甲酸、间苯二甲酸、水杨酸、邻氨基苯甲酸、磺基水杨酸)的配合物。经元素分析确定其组成结构式。研究了它们的红外吸收光谱、紫外吸收光谱及荧光光谱。紫外光谱的研究表明,配合物的紫外吸收主要表现为配体的吸收;红外光谱的研究表明,配合物的红外光谱不同于自由配体的红外光谱;荧光光谱的研究表明,铽与这六个配体的配合物都表现出较好的荧光性能,并发现磺基水杨酸铽配合物在本实验系列中其荧光发射最强。

Rare earth complexes have become excellent luminescence materials, this is related to lanthanide ions＇ peculiar characteristics, and have potential use in laser, photoluminescence and electroluminescence. Rare earth complexes with aromatic carboxylic acids are a kind of luminescent materials with good properties. So much attention was paid to the fluorescence properties of these complexes. There are some reports about fluorescence properties of the complexes of a part of rare earth with phthalic acid and terbium with benzoic acid and salicylic acid. However, no report on systemic study of the fluorescence properties concerning rare earth complexes with different aromatic carboxylic acids has been reported. For this purpose, we have synthesized fourteen complexes of Sm, Eu, Tb, Dy with benzoic acid derivatives ： RC6H4COOH （ R = o-NH2, H, p-NH2, o-OH,m-Cl, o-COOH, m-COOH, p-COOH, p-OH, m-NO2, 3,5-Dinitro, p-Br, o-I, 2-OH-5-SO3H ） and it is found that the complexes of Sm and Dy with these aromatic acids show little fluorescence, but Eu and Tb with some of these aromatic acids show strong fluorescence under the excitation of UV, and that the complexes of terbium with sulfosalicylic acid have the strongest fluorescence intensity. In the present paper, terbium complexes with aromatic acids were synthesized and their fluorescence properties were investigated. The synthetic process was as follows： The aqueous TbCl3 solution was slowly added to ligand solution according to the molar ratio of Tb^3＋ ： ligand = 1 ： 3 or 2： 3 （ phthalic acid, m-phthalic acid） at 80 ℃ under stirring. The pH of the mixture was adjusted to 6.0 - 6.5 by addition of sodium hydroxide solution. Thus, white precipitates of the complexes came into being. After another two hours, stop stirring, the mixture was cooled to room temperature. The white precipitates of the complexes were filtered, washed with deionized water and ethanol till no chloridion could be found, then dried at 85 ℃ under vacuum for 4 h. The compositions of samples were identified by elemental analyses. UV, IR of the complexes also have been investigated. The UV spectra indicated that the complexes＇ ultraviolet absorption was mainly the ligands＇ absorption, but the location of peak drifted. The IR spectra showed that the IR spectra of complexes are different from those of free ligands and the band at 400 - 500 cm^- 1, due to the stretching vibration of Tb-O, is absent for free ligands. The fluorescence properties were investigated by using luminescence spectroscopy, the results showed that all the six complexes of terbium exhibited excellent luminescence, due to the transition from the lowest excited state 5^D4 to 7^FJ ground state manifold, and the complexes of terbium with sulfosalicylic acid had the strongest fluorescence intensity.