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Issue 11, 2002
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Preparation and photo-physical characterisation of nanocomposites obtained by intercalation and co-intercalation of organic chromophores into hydrotalcite-like compounds

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Abstract

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 flash 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.

Graphical abstract: Preparation and photo-physical characterisation of nanocomposites obtained by intercalation and co-intercalation of organic chromophores into hydrotalcite-like compounds

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Publication details

The article was received on 07 May 2002, accepted on 02 Jul 2002 and first published on 03 Oct 2002


Article type: Paper
DOI: 10.1039/B204393A
J. Mater. Chem., 2002,12, 3316-3323

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    Preparation and photo-physical characterisation of nanocomposites obtained by intercalation and co-intercalation of organic chromophores into hydrotalcite-like compounds

    G. G. Aloisi, U. Costantino, F. Elisei, L. Latterini, C. Natali and M. Nocchetti, J. Mater. Chem., 2002, 12, 3316
    DOI: 10.1039/B204393A

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