Self-assembly of layered organosilicas based on weak intermolecular interactions

New layered hybrid organic-inorganic materials were obtained directly by hydrolysis and polycondensation of monosilylated precursors of type (EtO)(3)Si(CH(2))(3)NH(C=O)NHC(n)H(2n+1) (n = 3, 8, 12 and 16). These precursors were easily prepared by reaction between commercially available triethoxysilylpropylisocyanate and primary aminoalkanes. The obtained materials were characterized by combining elemental analysis, X-ray powder diffraction, (13)C, (29)Si NMR and FT-IR spectroscopies. They were found to be well condensed, and stable in water. We showed that their formation results from a cooperative effect between hydrogen bonding interactions originating from ureido groups and hydrophobic interactions between the long alkyl chains. There is no formation of material when n = 2, or from (EtO)(3)SiC(n)H(2n+1) when n = 18, thus proving that both types of weak intermolecular interactions are required. The chelating property of these materials towards europium(III) ions was tested.