title: Kinetics of intercalation of fluorescent probes in magnesium-aluminium layered double hydroxide within a multiscale reaction-diffusion framework.
abstract: 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'.
authors.affiliation: Department of Chemistry, American University of Beirut, PO Box 11-0236, Riad El-Solh 1107 2020, Beirut, Lebanon.
authors.forename: Daniel
authors.initials: D
authors.lastname: Saliba
authors.affiliation: Department of Chemistry, American University of Beirut, PO Box 11-0236, Riad El-Solh 1107 2020, Beirut, Lebanon mazen.ghoul@aub.edu.lb.
authors.forename: Mazen
authors.identifier: http://orcid.org/0000-0002-4119-3078
authors.initials: M
authors.lastname: Al-Ghoul
mesh_terms: D000536:Aluminum Hydroxide / Q000032:analysis / Q000737:chemistry*; D003198:Computer Simulation; D004058:Diffusion; D005456:Fluorescent Dyes / Q000737:chemistry*; D006878:Hydroxides / Q000737:chemistry; D007364:Intercalating Agents / Q000032:analysis / Q000737:chemistry*; D007700:Kinetics; D008276:Magnesium Hydroxide / Q000032:analysis / Q000737:chemistry*; D008422:Materials Testing / Q000379:methods; D008956:Models, Chemical; D008958:Models, Molecular; D013050:Spectrometry, Fluorescence / Q000379:methods*
chemical_list: D005456:Fluorescent Dyes; D006878:Hydroxides; D007364:Intercalating Agents; D000536:Aluminum Hydroxide; D008276:Magnesium Hydroxide
keywords: fluorescence; intercalation; layered double hydroxide; reaction–diffusion