2-(4-氟代苯甲酰基)苯甲酸-铕配合物的合成、结构表征及荧光性能的研究

以硝酸铕、2-(4-氟代苯甲酰基)苯甲酸(HL)、1,10-菲咯啉(Phen)和三苯基氧膦(TPPO)合成了EuL₃(H₂O)₆,EuL₃Phen(H₂O)₄和EuL₃(TPPO)(H₂O)₅三种固态配合物。用元素分析、红外光谱、核磁共振氢谱对配合物进行了组分确定和结构表征。IR表明，2-(4-氟代苯甲酰基)苯甲酸与Eu3+形成配合物后，位于1 692 cm-1处羧基的ν_CO峰消失，2 500～3 200 cm-1处羧基的ν_O—H峰也消失，出现了羧酸盐特有的反对称伸缩振动吸收峰(ν_as(CO-₂))和对称伸缩振动吸收峰(ν_s(CO-₂))，且Δν(ν_as(CO-₂)-ν_s(CO-₂))与钠盐的Δν相近，说明羧酸根与Eu3+以对称双齿桥式配位。在1H NMR中，形成配合物后第一配体苯环上的质子峰变为宽峰且移向高场，Phen和TPPO中质子化学位移移向低场。室温下测定了配合物的荧光激发光谱和发射光谱，激发光谱表明配合物EuL₃(H₂O)₆,EuL₃Phen(H₂O)₄和EuL₃(TPPO)(H₂O)₅的最佳激发波长分别为353.0，355.0和357.0 nm;发射光谱均显示Eu3+离子的特征发射光谱，且表明Phen对Eu3+离子的荧光发射有明显增强作用。

Study on Synthesis,Structure Characterization and Fluorescence of Europium Complexes of 2-(4-Fluorobenzoyl) Benzoic Acid

The present paper reports three new europium complexes, EuL₃(H₂O)₆,EuL₃Phen(H₂O)₄ and EuL₃(TPPO)(H₂O)₅,synthesized with Eu(NO₃)₃·6H₂O, 2-(4-fluorobenzoyl) benzoic acid, Phen and TPPO(L=2-(4-fluorobenzoyl) benzoic acid, Phen=1,10-phenanthroline, TPPO=triphenyl phosphine oxide). Their composition and chemical structures were characterized by elemental analysis, IR and 1H NMR spectroscopy. The IR spectra indicated that all complexes exhibited the characteristic peaks of carboxylate, asymmetric stretching vibration (ν_as(CO-₂)) and symmetric stretching vibration (ν_s(CO-₂)) peaks; the CO stretching band at 1 692 cm-1 of COOH and the O—H stretching band around 2 500-3 200 cm-1 disappeared. All these complexes had a smaller Δν(νas(CO-₂)-ν_s(CO-₂)) value than that of NaL, so the carboxylate groups coordinated with the europium ion in the form of bridging bidentate. In 1HNMR, the signals of hydrogen in 2-(4-fluorobenzoyl) benzoic acid became wide and shifted upfield, and those in Phen, TPPO shifted downfield. The excitation and emission spectra were recorded at room temperature. The excitation spectra showed that the optimum excitation peaks of these three complexes, EuL₃(H₂O)₆,EuL₃Phen(H₂O)₅ and EuL₃(TPPO)(H₂O)₅,were at 353.0, 355.0 and 357.0 nm, respectively. All these three complexes showed Eu3+ ion characteristic emission bands, the electron-dipole transition 5D₀→7F₂ and magnetism dipole transition 5D₀→7F₁; their emission peaks were at 596.0，617.0;596.0，619.0;595.0，620.0 nm, and the relative intensities were 1.1，8.6;15.2，100.0;3.6，23.2, respectively. The intensity of 5D₀→7F₂ was stronger than that of 5D₀→7F₁,which indicated that europium ions were at asymmetric center. The emission intensities of europium ions were greatly sensitized by Phen.