Universidade de Franca, Av. Dr. Armando Salles Oliveira, Parque Universitário, 201, 14404-600, Franca, SP, Brazil.
ACS Appl Mater Interfaces. 2011 Apr;3(4):1311-8. doi: 10.1021/am2001086. Epub 2011 Apr 7.
Luminescent hybrid materials derived from kaolinite appear as promising materials for optical applications due to their specific properties. The spectroscopic behavior of terbium picolinate complexes covalently grafted on kaolinite and the influence of the secondary ligand and thermal treatment on luminescence are reported. The resulting materials were characterized by thermal analysis, element analysis, X-ray diffraction, infrared absorption spectroscopy, and photoluminescence. The thermogravimetric curves indicated an enhancement in the thermal stability up to 300 °C for the lanthanide complexes covalently grafted on kaolinite, with respect to the isolated complexes. The increase in the basal spacing observed by X-ray diffraction confirmed the insertion of the organic ligands into the basal space of kaolinite, involving the formation of a bond between Al-OH and the carboxylate groups, as evidenced by infrared spectroscopy. The luminescent hybrid material exhibited a stronger characteristic emission of Tb(3+) compared to the isolated complex. The excitation spectra displayed a broad band at 277 nm, assigned to a ligand-to-metal charge transfer, while the emission spectra presented bands related to the electronic transitions characteristic of the Tb(3+) ion from the excited state (5)D(4) to the states (7)F(J) (J=5, 4, and 3), with the 4→5 transition having high intensity with green emission.
基于其独特的性质，源自高岭石的发光杂化材料在光学应用中具有广阔的应用前景。本文报道了固载在高岭石上的 picolinate 铽配合物的光谱行为以及第二配体和热处理对发光的影响。采用热分析、元素分析、X 射线衍射、红外吸收光谱和光致发光对所得材料进行了表征。热重曲线表明，与游离配合物相比，固载在高岭石上的镧系元素配合物的热稳定性在 300°C 时得到增强。X 射线衍射观察到的基面间距增大证实了有机配体插入高岭石的基面空间，这涉及到 Al-OH 和羧酸盐基团之间形成键，这一点可以通过红外光谱得到证明。与游离配合物相比，发光杂化材料表现出更强的 Tb(3+)特征发射。激发光谱在 277nm 处呈现出宽的带，归因于配体到金属的电荷转移，而发射光谱则呈现出与 Tb(3+)离子从激发态（5）D(4)到（7）F（J）（J=5、4 和 3）的电子跃迁有关的谱带，其中 4→5 跃迁具有高强度的绿色发射。
