【摘要】 以对苯二甲酸(L′)为桥联配体,18冠6(L)为配体,稀土(Eu Tb)为中心离子,合成了一系列超分子化合物,对其进行了元素分析,红外光谱及荧光性能测量。确定了配合物的组成为(Eu1-xTbx)2L2L′(ClO4)4·H2O(6+3x);推测出Eu3+离子直接与冠醚氧原子配位,而较小半径的Tb3+与18冠6则通过H2O配位。H2O分子与冠醚氧原子以氢键形式连结,对苯二甲酸以双齿形式桥联两个稀土离子冠醚配合物,形成双核结构单元;在此配合物中,Tb3+离子对Eu3+离子的发光有一定的敏化作用,而Eu3+离子对Tb3+离子的荧光却有强的猝灭作用。更多还原

【Abstract】 A series of dinuclear complexes with different Eu³⁺ to Tb³⁺ ratios with p-phthalic acid （L′） and ligand of 18 crown 6 （L） have been synthesized. Elemental analysis,IR absorption spectra and fluorescence spectra have been studied respectively.The compositions of the complexes were confirmed to be(Eu_1-xTb_x)₂L₂L′（ClO₄）₄·H₂O_（6+3x）. Smaller Tb³⁺ coordinated with water molecules, which were hydrogen bonded with crown ether while Eu³⁺ coordinated with crown ether directly may be concluded.Shimadzu FR-5301PC fluorescence spectrophotometer was employed to measure the luminescence spectra at room temperature. As results showed the excitation wavelength changed with the molar ratios of Eu³⁺ to Tb³⁺. The optimum excited wavelength is at the same position（298 nm） when contents of Tb³⁺ is 100% and 90%, respectively. It changes to 254 nm when Tb³⁺ content decrease to 70% and Eu³⁺ content rise to 30%. The measurement results of the emission spectra of the complexes indicated that the emission peaks of Tb₂L₂L′（ClO₄）₄·12H₂O consisted of four groups of emission peaks and Eu₂L₂L′（ClO₄）₄·6H₂O has three, while (Eu_1-xTb_x)₂L₂L′（ClO₄）₄·H₂O_（6+3x） has five. The previous are as following: peaks at 490.0, 545.8, 585.6 and 621.0 nm are as the Tb³⁺ ions⁵D₄→⁷F_J（J=6,5,4,3） transitions correspondingly, among them the emission from⁵D₄→⁷F₅ is the strongest belonging to hypersensitive transition（ΔJ=2）. The latter are following: first group, 578.6 nm belongs to⁵D₀→⁷F₀ transitions of Eu³⁺, the second group,588.2 nm and 592.2 nm, both belong to⁵D₀→⁷F₁ transitions of Eu³⁺, the third group, 613.6nm and 618.2 nm both belong to⁵D₀→⁷F₂ transitions of Eu³⁺. The last one: they appear at about 490, 545, 579, 585 and 620 nm. The first and second fluorescence bands centered around 490 nm and 545 nm corresponding to⁵D₄→₇F₆ and⁵D₄→⁷F₅ transitions of Tb³⁺ ions. Overlapped peaks at 585 nm and 620 nm were found caused by interaction between⁵D₀→⁷F₁ ,⁵D₀→⁷F₂ transitions of Eu³⁺and⁵D₀→⁷F₄ ,⁵D₄→⁷F₃ transitions of Tb³⁺. Variance of fluorescence spectra emission peaks showed that there are interaction between Eu³⁺ ions and Tb³⁺ ions in (Eu_1-xTb_x)₂L₂L′（ClO₄）₄·H₂O_（6+3x）.The fluorescence emission intensity of Tb³⁺ （⁵D₄→⁷F₅） in Tb₂L₂L′（ClO₄）₄·12H₂O was 1 313.6 comparing with 29.8 of Eu³⁺ （⁵D₀→⁷F₂） transitions in Eu₂L₂L′（ClO₄）₄·6H₂O. Concluded from R=I_d/I_c（I_d=values of the fluorescence emission intensity determined, I_c=calculated values） is below 1.0 at 490 nm and 545 nm (corresponding to Tb³⁺⁵D₄→⁷F₆ and⁵D₄→⁷F₅ transitions) even at 585 nm. However when ratio of Eu³⁺ and Tb³⁺ is 0.9∶0.1～0.7∶0.3, the R values for peaks at 579 nm and 620 nm are higher than 1.0 collectively, Eu³⁺ will quench Tb³⁺ fluorescence while Tb³⁺ will sensitize Eu³⁺.更多还原