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M.-A. Néouze, M. Kronstein, M. Litschauer, J. Roeser, A. Thomas:
"Building and tailoring ionic nanoparticle networks";
Talk: E-MRS Spring Meeting 2012, Strasbourg; 2012-05-14 - 2012-05-18; in: "E-MRS Spring Meeting 2012 - Program", (2012), S2-6.

Recently ionic nanoparticle networks (INN) were reported in the frame of the remarkable development of new inorganic-organic hybrid materials based on nanoparticle assembly. The original method we developed to synthesize 3-D networks is based on the functionalization of metal oxide nanoparticles with ionic linkers, the bridging ligands containing imidazolium units. Recent publications pointed out the powerful synergy of ionic species with nanoparticles. Such synergy makes those new inorganicorganic hybrid materials promising candidates for many applications such as photoluminescence, catalysis or electrolytes. The length and rigidity of the imidazolium bridging units was varied. The short-range order of the network was investigated via small-angle X-ray scattering. This short-range order was interpreted as originating from self-organization of the aromatic rings of the ligands bridging the nanoparticles by means of π-stacking. This hypothesis was validated by luminescence investigations on the hybrid materials. The combination of high imidazolium content with the presence of metal centers, also able to coordinate to CO2 molecules, makes the hybrid materials INN highly promising catalyst for CO2 activation reactions. INNs already showed highly promising results as base catalysts for the cycloaddition of CO2 to different starting epoxides. The reactions were performed under relatively mild conditions (e.g. low CO2 pressure) in comparison with reported results. The imidazolium bridging units in the final hybrid material renders the INN tailorable. For example, anion metathesis allows tuning the hydrophilic character of the hybrid material; as a consequence hexafluorophosphate INN will be hydrophobic whereas chloride INN is hydrophilic.

Project Head Marie-Alexandra Néouze:
Ionische Verknüpfung von Nanopartikeln