Hybrid Silica Based Materials as New Solid Phase Extractants.

ABSTRACTOrganic-inorganic hybrids exhibiting specific properties are easily prepared by incorporation of organic fragments in an inorganic network. Increasing attention is being paid to hybrid silsesquioxane gels, which are prepared by sol-gel hydrolysis condensation of organic molecules containing two or more trialkoxysilyl substituents. These hybrids consist of a mixed three-dimensional network, where the organic fragment, cross-linking siloxane chains, is part of the framework. Owing to the presence of a strong Si-C bond between the organic and the inorganic fragments, highly stable hybrid network are produced in this way. A variety of materials can be produced according to the intrinsic properties of the organic. We report here the preparation of hybrid materials with complexing properties upon hydrolysis-condensation of ligands functionalized by Si (OR)3 groups. New hybrid silica based materials containing malonamide ligands have been prepared by sol-gel hydrolysis condensation of functionalized precursors and have been used as solid phase extractants for the complexation of actinides. This approach is quite different from the classical immobilization procedure of complexing agents. The sol-gel approach allows one to adjust the ligand loading and to achieve some control and some tuning of the ligand environment since the oxide matrix is built around the complexing moieties. These hybrids proved to be highly efficient extracting solids.