Preparation and photophysical characterisation of Zn-Al layered double hydroxides intercalated by anionic pyrene derivatives†
Preparation and photophysical characterisation of Zn-Al layered double hydroxides intercalated by anionic pyrene derivatives†
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DOI：
10.1039/b715319h
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发表时间：
2008-02
影响因子：
--
通讯作者：
S. Gago;Telma Costa;J. S. D. Melo;I. Gonçalves;M. Pillinger
中科院分区：
文献类型：
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作者：
S. Gago;Telma Costa;J. S. D. Melo;I. Gonçalves;M. Pillinger
通过离子交换过程合成了由 1,3,6,8-芘四磺酸盐 (PTS)、1-芘磺酸盐 (PS) 和 1-芘羧酸盐 (PC) 阴离子插层的 Zn-Al 水滑石化合物。通过不同温度下的粉末X射线衍射、热重分析、FTIR、13C{1H}CP/MAS NMR和光致发光技术对材料进行了表征。在完全水合状态下，Zn-Al-PTS 的层间距离为 13.7 A，Zn-Al-PS 的层间距离为 18.9 A，Zn-Al-PC 的层间距离为 24.8 A。这些可以归因于插入的 PTS 阴离子的单层排列和 1-芘基衍生物的双层排列。样品表现出不同的热分解途径，对于 Zn-Al-PTS，物理吸附水和层间水的去除导致有机阴离子相对于氢氧化物层的方向发生变化。水合后结构转变是完全可逆的。块体材料的光物理表征基于其发射和荧光激发光谱以及荧光寿命的测定。从稳态（单体和“类准分子”带）和时间分辨（三重指数衰减）数据，可以证明存在与芘二聚体和单体具有相似特征的结构（通过与 PS 和 PC 的稀溶液的发射进行比较）、预缔合和（可能）动态准分子种类。
Zn–Al hydrotalcite-like compounds intercalated by 1,3,6,8-pyrenetetrasulfonate (PTS), 1-pyrenesulfonate (PS) and 1-pyrenecarboxylate (PC) anions were synthesised by an ion-exchange procedure. The materials were characterised by powder X-ray diffraction at different temperatures, thermogravimetric analysis, FTIR, 13C{1H} CP/MAS NMR and photoluminescence techniques. In the fully hydrated states, the interlayer distances are 13.7 A for Zn–Al–PTS, 18.9 A for Zn–Al–PS, and 24.8 A for Zn–Al–PC. These can be ascribed to a monolayer arrangement for intercalated PTS anions and bilayer arrangements for the 1-pyrenyl derivatives. The samples exhibit different thermal decomposition pathways, and in the case of Zn–Al–PTS the removal of physisorbed and interlayer water leads to a change in the orientation of the organic anion with respect to the hydroxide layers. The structural transformation is fully reversible upon hydration. The photophysical characterisation of the bulk materials was based on the determination of their emission and fluorescence excitation spectra, and the fluorescence lifetimes. From the steady-state (monomer and “excimer-like” bands) and time-resolved (triple exponential decays) data, evidence for the presence of a structure with similar characteristics to pyrene dimer together with monomer (by comparison with the emission of dilute solutions of PS and PC), pre-associated and (possibly) dynamic excimer species could be presented.