溶液中稀土(Eu、Tb)络合物的敏化荧光

本文应用荧光滴定法研究了稀土络合物的敏化荧光,比较了某些稀土的二元络合物的激发光谱和荧光光谱,讨论了一些因素如配位体的配比、络合物浓度、酸碱度及其它络合剂对稀土络合物荧光的影响。对三元络合物的能量转移途径也进行了考查,了解到三元络合物中同时存在两个敏化剂配位体时,由于配位体络合力的不同,光能的吸收主要是通过与稀土结合较强的配位体向稀土离子作能量转移,所研究络合物的能量转移机理属于Dexter型的短程交换相互作用。

THE SENSITIZED FLUORESCENCE OF RARE EARTH (Eu,Tb) COMPLEXES IN SOLUTION

The sensitized fluorescence oi binary and ternary complexes of RE(Eu, Tb)has been studied by the Fluorescence Titration Method, the sensitizers used being mainly β-diketones and aromatic amines.Rare earth europium and terbium, each has its own characteristic fluorescence spectra (Em). With the change of the ligands constituting the complexes, the position of the Em peaks of the RE ions remains basically unchanged whereas their intensities and shapes show some variation.The Eu complexes have two distinct fluorescence peaks in general, corresponding to electric dipole transition(ED)of 610 nm and magnetic dipole transition (MD) of 587 nm.The ratio MD/ED reflects the symmetry of the environment of the RE ions (the smaller the ratio, the less the symmetry).The MD/ED of Eu-|S-diketones complex has been deter-dmined≈0.125, and the MD/ED of Eu-o-phenanthrolein or Eu-2.2''dipyri-dine complex≈0.5.The symmetry of the former is less than that of the latter. The closeness of the MD/ED ratio of the complexes of the same kind means that they have the similarity in the numbers of the ligands cholating on RE ion, their occupation position and the structure of chelates.The spectra of excitation(Ex) of the RE complexes are also related to the kind of ligands. The Ex shapes of Eu-β-diketone complexes are similar each other, they have two peaks, one strong and one weak.More difference exists in the case of Eu-aro-matic amine complexes, but their common point is that each of them has three peaks.The Ex between different kind of complexes are still more different.The above phenomena also reflect that the structure and property of the chelating ligand function group linking RE ion are directly related to the fluorescence spectra of the complexes.