Saliba Daniel, Al-Ghoul Mazen
Department of Chemistry, American University of Beirut, PO Box 11-0236, Riad El-Solh 1107 2020, Beirut, Lebanon.
Department of Chemistry, American University of Beirut, PO Box 11-0236, Riad El-Solh 1107 2020, Beirut, Lebanon
Philos Trans A Math Phys Eng Sci. 2016 Nov 13;374(2080). doi: 10.1098/rsta.2016.0138.
We report the synthesis of magnesium-aluminium layered double hydroxide (LDH) using a reaction-diffusion framework (RDF) that exploits the multiscale coupling of molecular diffusion with chemical reactions, nucleation and growth of crystals. In an RDF, the hydroxide anions are allowed to diffuse into an organic gel matrix containing the salt mixture needed for the precipitation of the LDH. The chemical structure and composition of the synthesized magnesium-aluminium LDHs are determined using powder X-ray diffraction (PXRD), thermo-gravimetric analysis, differential scanning calorimetry, solid-state nuclear magnetic resonance (SSNMR), Fourier transform infrared and energy dispersive X-ray spectroscopy. This novel technique also allows the investigation of the mechanism of intercalation of some fluorescent probes, such as the neutral three-dimensional rhodamine B (RhB) and the negatively charged two-dimensional 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS), using in situ steady-state fluorescence spectroscopy. The incorporation of these organic dyes inside the interlayer region of the LDH is confirmed via fluorescence microscopy, solid-state lifetime, SSNMR and PXRD. The activation energies of intercalation of the corresponding molecules (RhB and HPTS) are computed and exhibit dependence on the geometry of the involved probe (two or three dimensions), the charge of the fluorescent molecule (anionic, cationic or neutral) and the cationic ratio of the corresponding LDH.This article is part of the themed issue 'Multiscale modelling at the physics-chemistry-biology interface'.
我们报道了利用反应扩散框架（RDF）合成镁铝层状双氢氧化物（LDH）的方法，该框架利用了分子扩散与化学反应、晶体成核和生长的多尺度耦合。在RDF中，允许氢氧根阴离子扩散到含有沉淀LDH所需盐混合物的有机凝胶基质中。使用粉末X射线衍射（PXRD）、热重分析、差示扫描量热法、固态核磁共振（SSNMR）、傅里叶变换红外光谱和能量色散X射线光谱法确定合成的镁铝LDH的化学结构和组成。这种新技术还允许使用原位稳态荧光光谱研究一些荧光探针的嵌入机制，如中性三维罗丹明B（RhB）和带负电荷的二维8-羟基芘-1,3,6-三磺酸（HPTS）。通过荧光显微镜、固态寿命、SSNMR和PXRD证实了这些有机染料在LDH层间区域的掺入。计算了相应分子（RhB和HPTS）嵌入的活化能，结果表明其依赖于所涉及探针的几何形状（二维或三维）、荧光分子的电荷（阴离子、阳离子或中性）以及相应LDH的阳离子比率。本文是主题为“物理 - 化学 - 生物学界面的多尺度建模”特刊的一部分。
