摘要
介孔分子筛MCM-41具有规则排列的纳米量级的孔道,可以作为宿主封装其他材料。利用这一性质,将激光染料罗丹明6G分子封装在介孔分子筛MCM-41中形成了纳米复合物。用透射电镜、小角度X射线衍射和荧光光谱等方法对纳米复合物的性质进行了分析。用波长为480nm的光对纳米复合物进行激发,得到的发光峰为531nm。与无限稀罗丹明6G乙醇溶液的发光峰相比,这一发光峰有15nm的蓝移和明显的宽化。我们认为当罗丹明6G分子封装在MCM-41的介孔中时,罗丹明6G分子与介孔分子筛孔道表面分子之间存在较强的相互作用(包括氢键、静电吸引等),导致电子云被局域在具有较强吸引力的分子筛表面原子周围,引起激发态能量升高,发光峰蓝移。
The mesostructured/mesoporous materials have attracted so much interest because of their large pore dimensions and volumes as well as high internal surface areas to use as potential catalysts and separation media. Recently the nanocomposites which are incorporated the organic molecules in the periodic mesostructured/mesoporous materials have received much attention. More efforts have been directed toward the goal of obtaining dye-doped structures for optical applications. In this paper the Rhodamine 6G (Rh 6G) molecules were incorporated in the nanometer pores of MCM-41 to form nanocomposite exhibiting different luminescent property. Such nanocomposite offer new opportunities for controlling the local environments for occluded dye molecules. In this letter we synthesized the polycrystalline powder of the mesostrucure MCM-41 by using cetyltrimothylammonioum bromide as the template. After calcined in air, we obtained the mesoporous MCM-41 framework. The dimensions of the mesopores of the MCM-41 framework are about 3nm. The Rh 6G/MCM-41 assemblies were obtained through ion exchange mixing of the calcined MCM-41 and Rh 6G solution at the concentration of 10-4 mol/L. The mixtures were stirred for 48h at room temperature. Then the nanocomposite was washed thoroughly with ethanol and dried in air. The nanocomposite was characterized by transmission electron microscopy (TEM),X-ray diffraction (XRD),and fluorescence measurements. An obvious blue shift and spectral broadening were observed in the emission of the nanocomposite, compared with Rhodamine 6G in ethanol solution at the concentration less then 10-10 mol/L. Considering the strong guest-host interaction between the Rh 6G molecules and the MCM-41 mesopores, the blue shift was attributed to the partial localization of the π-electrons in the chromophore. The intramolecular charge-transfer is originated from the strong guest-host interaction between the Rh 6G molecules and the MCM-41 mesopores. And the broad emission of the Rh 6G/MCM-41 can be interpreted as distribution of different site-specific emission. The result indicates that the nanocomposite represents useful property. It suggests a new approach to tunable wavelength range of dye laser.
出处
《发光学报》
EI
CAS
CSCD
北大核心
2003年第6期637-641,共5页
Chinese Journal of Luminescence
基金
国家重点基础研究发展规划项目(973G1998061309)
国家自然科学基金(1027402)
吉林省科委(19990514)资助项目
