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Résumé:

A new method has been developed for the synthesis of shaped-controlled bridged silsesquioxanes by the acid hydrolysis of urea-derived silylated precursors. This method is based on the ability of the hydrogen bonds of the urea groups to organize the molecules in a supramolecular architecture and provides after hydrolysis a new access to hybrid materials with controlled morphologies. A chirality transcription from a molecular precursor to a hybrid solid has been achieved. A right- and a left-handed helices have been obtained respectively from the chiral (R,R)- and the (S,S)-enantiomers of the diureido derivatives of trans-diaminocyclohexane. In a related way, a long range ordered hybrid solid has been obtained. Long carbon chain as spacer between the urea groups of the precursor affords lamellar hybrid silicas.