[Zurück]

M.-A. Néouze, M. Litschauer, M. Kronstein, J. Roeser:
"Imidazolium Nanoparticle Networks: "Solid Ionic Liquids" Catalysts for CO2 Activation";
Vortrag: MRS Spring Meeting 2012, San Francisco (eingeladen); 09.04.2012 - 13.04.2012; in: "MRS Spring Meeting 2012 - Program & Exhibit Guide", (2012), S. BBB1.4.

In the context of reducing global emissions of CO2, believed to be partly responsible for global warming and climate change, the use of CO2 as industrially useful chemical feedstock is a major issue. Indeed, CO2 can be seen as a sustainable carbon source, in terms of renewability, abundance, and non-toxicity. Thus, the development of new efficient (heterogeneous) catalysts for CO2 conversion remains of major concern. Among others, ionic liquids showed promising results in the conversion of CO2 to organic carbonates, which, due to their high oxidation state, appear to be an interesting synthetic target.
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. 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. Moreover, the INN materials are solid which allow an easy separation of the catalyst after reaction. Moreover, 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. In this communication, we will report the efficient use of the chloride INNs 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. In this communication the catalytic performances of INN with mono- and di-imidazolium bridging units as well as with various counter anions will be presented.