Yang Yue-tao, Chen Wan-song, Li Jun-Jia, Zhang Shu-yi
Key Laboratory of Modern Acoustics, Ministry of Education, Nanjing University, Nanjing 210093, China.
Guang Pu Xue Yu Guang Pu Fen Xi. 2008 Sep;28(9):2024-7.
Silica matrices, due to their good optical, thermal and chemical properties, are suitable candidates for the hosts of luminescent lanthanide complexes. However, lanthanide complexes would be unstable in the most common sol-gel precursor solution. It is important to study the coordination environment of lanthanide ions and the formation of lanthanide complexes in silica gels. In the present work, lanthanide complexes Ln(Sal)3 x H2O(Ln3+:La3+, Nd3+ and Tb3+; Sal:salicylic acid) were incorporated into silica gels via a sol-gel process. PA technique was firstly used to monitor the formation of lanthanide complexes in silica gels. Upon heat treatment at 110 degrees C, PA intensity of the ligand increased for Tb3+, La3+ and Nd3+ complexes in silica gels, respectively, while this difference could not be observed for the wet gels (samples without heat treatment). By comparison with fluorescence spectra, experimental data indicate that lanthanide complexes decompose in wet gels. The formation of lanthanide complexes in silica gels is discussed from two aspects: radiative and nonradiative processes. Co-luminescence effect was found for lanthanide complexes with aromatic carboxylic acid doped silica gels for the first time. For Tb0.8 Ln0.2 (Sal)3 x H2O (Ln3+:Gd3+ or Nd3+)-doped silica gel, the addition of Gd3+ increased the luminescence efficiency of Tb3+, while the luminescence of Tb3+ was quenched remarkably with the addition of Nd3+. Possible mechanism behind the co-luminescence phenomena of lanthanide complexes-doped silica gels is discussed.
由于具有良好的光学、热学和化学性质，二氧化硅基质是发光镧系配合物主体的合适候选材料。然而，镧系配合物在最常见的溶胶 - 凝胶前驱体溶液中会不稳定。研究镧系离子的配位环境以及硅胶中镧系配合物的形成很重要。在本工作中，通过溶胶 - 凝胶法将镧系配合物Ln(Sal)₃·xH₂O（Ln³⁺：La³⁺、Nd³⁺和Tb³⁺；Sal：水杨酸）掺入硅胶中。首次使用光声（PA）技术监测硅胶中镧系配合物的形成。在110℃热处理后，硅胶中Tb³⁺、La³⁺和Nd³⁺配合物的配体光声强度分别增加，而对于湿凝胶（未热处理的样品）则未观察到这种差异。通过与荧光光谱比较，实验数据表明镧系配合物在湿凝胶中分解。从辐射和非辐射过程两个方面讨论了硅胶中镧系配合物的形成。首次发现芳香羧酸掺杂的硅胶中镧系配合物存在共发光效应。对于Tb₀.₈Ln₀.₂(Sal)₃·xH₂O（Ln³⁺：Gd³⁺或Nd³⁺）掺杂的硅胶，添加Gd³⁺提高了Tb³⁺的发光效率，而添加Nd³⁺则显著猝灭了Tb³⁺的发光。讨论了镧系配合物掺杂硅胶共发光现象背后的可能机制。
