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以4-氯苯甲酸(4-ClBA)、4-溴苯甲酸(4-BrBA)和4-碘苯甲酸(4-IBA)为配体合成了三种4-卤代苯甲酸铽的稀土配合物Tb(4-ClBA)3,Tb(4-BrBA)3和Tb(4-IBA)3,紫外可见光吸收光谱表明,相同摩尔浓度的Tb(4-IBA)3的紫外吸收最强,Tb(4-BrBA)3的紫外吸收强度次之,Tb(4-ClBA)3的紫外吸收最弱,而荧光发射光谱表明,Tb(4-IBA)3和Tb(4-BrBA)3的荧光发射强度远小于Tb(4-ClBA)3的。从配体的结构及配体能级、稀土离子Tb3+能级、配体到稀土离子之间的能量传递等角度对该试验结果进行了分析探讨,结果表明苯甲酸对位的碘原子、溴原子和氯原子与苯环上的碳原子所形成的碳卤键热振动的不同是造成三种稀土配合物荧光强度差别较大的本质原因。
Three rare earth complexes of terbium 4-halobenzoate were synthesized with 4-chlorobenzoic acid (4-ClBA), 4-bromobenzoic acid (4-BrBA) and 4-iodobenzoic acid Tb (4-BrBA) 3 and Tb (4-IBA) 3 showed that UV absorption of Tb (4-IBBA) 3 with the same molar concentration was the highest and Tb (4-BrBA) 3, followed by Tb (4-ClBA) 3. The fluorescence emission spectra of Tb Much smaller than Tb (4-ClBA) 3. The experimental results were analyzed from the perspectives of the structure and ligand level of the ligand, the Tb3 + energy level of the rare earth ions, and the energy transfer between the ligand and the rare earth ions. The results show that the iodine atom, the bromine atom And the difference between the thermal vibration of the carbon halogen bond formed by the chlorine atom and the carbon atom on the benzene ring is the essential reason for the large difference in fluorescence intensity between the three rare earth complexes.