Résumé
An innovative and general method for the synthesis of shape-controlled bridged silsesquioxanes by the hydrolysis of urea-derived organo-bis(trialkoxy)silanes has been developed. This method relies on the ability of the hydrogen bonds of the urea groups to self-assemble the molecules in a supramolecular architecture. The controlled hydrolysis of the latter efficiently leads to new hybrid silsesquioxanes wirh sought-after morphologies. Following the reaction conditions (acid- or base-catalyzed hydrolysis) and also depending on the solvent used (purely aqueous or a mixture of water and ethanol), different forms of hybrid materials were obtained from the hydrolysis of chiral diureido derivatives of trans-diaminocyclohexane. Right- and left-handed helices were formed under acid-catalyzed hydrolysis of the enantiopure (R,R) and (S,S) compound respectively.