Preparation and photo-physical characterisation of nanocomposites obtained by intercalation and co-intercalation of organic chromophores into hydrotalcite-like compounds
Preparation and photo-physical characterisation of nanocomposites obtained by intercalation and co-intercalation of organic chromophores into hydrotalcite-like compounds
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DOI：
10.1039/b204393a
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发表时间：
2002-01-01
影响因子：
--
通讯作者：
Nocchetti, M
中科院分区：
文献类型：
--
作者：
Aloisi, GG;Costantino, U;Nocchetti, M
几种具有供体受体特性并含有羧基或磺酸基团 [香豆素-3-羧酸 (3-CCA)、9-蒽甲酸 (9-ACA)、4-苯甲酰基苯甲酸 (4-BBA) 和 2-萘磺酸 (2-NSA)] 的发色团已插入 Mg-Al 中 类水滑石化合物，通过阴离子交换过程和利用水滑石的“记忆效应”。通过X射线衍射、热分析和化学成分对所得插层化合物进行了表征。获得的数据表明，客体物质作为叉指阴离子的单膜容纳在层间区域，其中 C-COO- 或 C-SO3- 键几乎垂直于层平面。所研究的发色团对，3-CCA 9-ACA 和 4-BBA 2-NSA，由于其激发态的特性，可以引起能量转移过程。上述发色团对的共嵌入是通过不同的合成程序实现的。通过吸收和发射光谱以及激光闪光光解研究了单插层和共插层系统。 MgAl-9-ACA 的吸收光谱显示出 490 nm 附近的意外谱带，该谱带归因于聚集体。各种共嵌入样品的荧光特性取决于激发波长和制备方法，其控制层间区域中两种荧光团的相对量。在所有含有 9-ACA 的样品中，500 nm 左右的激发会产生归因于蒽聚集体的发射。在单插层和共插层样品中，荧光衰减分别令人满意地符合双指数和三指数函数。激光灰分光解实验表明，插层发色团的激发产生瞬态，这可归因于客体三联体，并且在共插层 4-BBA 2-NSA 复合材料的情况下，可能发生能量转移过程。
Several chromophores with donor acceptor properties and containing a carboxylic or sulfonic group [coumarin-3-carboxylic acid (3-CCA), 9-anthracenecarboxylic acid (9-ACA), 4-benzoylbenzoic acid (4-BBA) and 2-naphthalenesulfonic acid (2-NSA)] have been intercalated into Mg-Al hydrotalcite-like compounds, both via anion exchange procedures and by using the "memory effect" of the hydrotalcites. The obtained intercalation compounds have been characterised by X-ray diffractometry, thermal analysis and chemical composition. Data obtained indicate that the guest species are accommodated in the interlayer region as a monofilm of interdigitaded anions with the C-COO- or C-SO3- bond almost perpendicular to the layer plane. The pairs of chromophores investigated, 3-CCA 9-ACA and 4-BBA 2-NSA, can give rise to energy transfer processes because of the characteristics of their excited states. Co-intercalation of the above-mentioned pairs of chromophores has been achieved with different synthetic procedures. The mono-intercalated and co-intercalated systems were investigated by absorption and emission spectroscopy and by laser flash photolysis. The absorption spectrum of MgAl-9-ACA shows an unexpected band around 490 nm that was attributed to an aggregate. The fluorescence characteristics of the various co-intercalated samples depend on the excitation wavelength and on the preparation methods, which control the relative amounts of the two fluorophores in the interlayer region. In all the samples containing 9-ACA excitation around 500 nm generates an emission attributed to the anthracene aggregate. In mono-intercalated and co-intercalated samples, the fluorescence decays satisfactorily fit bi-exponential and tri-exponential functions, respectively. Laser ash photolysis experiments showed that excitation of the intercalated chromophores produces transients which can be attributed to the guest triplets and, in the case of co-intercalated 4-BBA 2-NSA composite, the probable occurrence of an energy transfer process.