Complex structures, such as living organisms or highly structured materials, have in common the fact that their inherent complexity may be accounted for by the tangled organization of a vast number of simple units. The complex behavior arises not necessarily from the atomic structure of the system, but from the orderly assembly of all, or part, of its constituents.[1,2] Self-assembly of synthetic soft-matter componentssuch as polymers, liquid crystals, surfactants, colloids, and organic/inorganic hybrids-results in regular hierarchically organized structures. [3][4][5] The importance of combining sol-gel methods and self-assembly routes to synthesize hierarchically structured organic/inorganic materials, with potential applications in the design of ion-transport microdevices, has been highlighted recently.[5]Silsesquioxanes ((RO) 3 -Si-R′-Si-(OR) 3 , where R and R′ are organic groups) and organosilanes (R′-Si-X 3 , where X = OR or Cl) are examples in which hierarchically ordered self-assembled architectures with well-defined morphologies at the macroscopic scale-such as ribbons stacked into lamellae, [6][7][8][9] 2D hexagonal structures, [9] twisted helical fibers with controlled handedness, [10] hollow tubes and spheres, [11] ladderlike superstructures, [12] and bilayered lamellar packing [13][14][15] are induced by weak interactions between the R′ organic spacers (hydrogen bonding, hydrophobic interactions, and p-p interactions).Despite the fact that work on silsesquioxanes has produced hierarchically ordered architectures, [6][7][8][9][10][11][12] so far the self-assembly of the simpler trifunctional alkylsilanes has been reported only sporadically. [13][14][15] In these examples, the design strategy relies on the self-organization of organophilic precursor molecules that become amphiphilic as hydrolysis proceeds to form hydrophilic silanol groups. As the hydrophilic parts (head groups) of alkylsilanetriols occupy less space than the hydrophobic ones, lamellar packing is favored. This anisotropic aggregation mechanism of alkyltrihydroxysilane species resembles that of amphiphilic surfactants and phospholipid molecules. Like the L-phase (lamellar phase) of phospholipids, alkylsilanes are characterized by a bimolecular layered pattern of stacks of alkyl chains perpendicular to the layers. The only known examples of bilayered lamellar packing in alkylsilanes are the microcrystalline poly(octadecylsiloxane)s prepared from n-alkyltrichlorosilanes, [13] and the hybrids synthesized from triethoxy- [14] and trimethoxy-based [15] alkylsilanes. Hydrophobic interactions between the organic chains are the main force driving the formation of these highly ordered packing structures. Although the relationship between structural complexity and self-assembly mechanisms has been given much consideration, the essential role played by higher organizing principles in determining emergent physical phenomena in soft-matter complex structures, although recognized (e.g., for the unpredictable electronic features of cholesterol-stilben...

Novel amide cross-linked alkylene/siloxane hybrid materials (di-amidosils) synthesized by the sol-gel process have been investigated. Two samples identified by the notation d-A(x) with x = 4 and 8 (where x is the number of methylene groups of the alkylene chain) have been produced as transparent, amorphous, rigid monoliths, thermally stable up to about 381 and 400 ºC, respectively. In the d-A(8) hybrid the siliceous framework is composed of [(SiO) 3 Si(CH 2)-] and [(SiO) 2 (HO)Si(CH 2)-] substructures. Structural unit distances of 4.1 and 4.2 Å and average interparticle distances of 12 and 17 Å have been determined for d-A(4) and d-A(8), respectively. In these compounds the alkyl chains are disordered and adopt gauche conformations. While a negligible proportion of the amide linkages remain non-bonded, the great majority of these groups belong to highly disordered strong hydrogen-bonded amide-amide associations. The hybrids introduced are room temperature white light emitters, presenting an emission large, broad band in the blue/purplishblue spectral region. The origin of such band have been ascribed to the convolution of donoracceptor pair (D-A) recombinations that occur in the NH groups of the urea linkages and in the siliceous nanodomains. The maximum quantum yield value of the d-A(8) di-amidosil is 5.4 %.

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