Preparation Of Chiral Organic-inorganic Hybrid Mesoporous Materials Using Achiral Surfactants As Templates

Organic-inorganic hybrid helical silicas were prepared using achiral cationic surfactants as supramolecular templates and chiral alcohols as co-structure-directing agents in the 25 wt% aqueous ammonia and NaOH solutions. Critical micelle concentrations of the surfactants can be reduced with the addition of the chiral alcohols which drive the formation of worm-shaped micelle and phase transition. The molecular chiral information can be transmitted to a supramolecular and showed in another form, such as helical structures. This method offers us an opportunity to fabricate chiral mesoporous materials through a simple approach. Helical organic-inorganic hybrid silicas containing different organic bridging groups such as 1,2-ethylene, methylene, 1,2-ethenylene, 1,4-phenylene were obtained. Helical mesporous hybrid silica nanorods, nanofibers, and M?bius Nanorings were obtained. Moreover, hierarchical porous structures, nanofibers with lamellar pores on their surfaces and concentric circular or rod-like pore channels inside, were obtained. The molar ratio of the co-structure-directing agent/surfactant is the key factor on controlling the morphology and pore architectures. For periodic mesoporous organosilicas, with bridging groups uniform distribution inside the walls, their groups bridge between the two silica atoms, which can enhance accessibility in absorbance and catalysis appliacations and sening devices, and thus gain the opportunities fou further modification. The formation mechanism was studied by taking field-emission electron microscopy and transmission electron microscopy images after different time.