Nanostructures Of Organic-inorganic Hybrid Silica Controlled Using Anionic Amphiphiles

Chiral nanomaterials, especially those with chirality at molecular levels attracted lots of researchers, due to their potential applications in chiral catalysis, separation and optics. A series of chiral anionic low-molecular-weight amphiphiles were synthesized according to literatures. Their self-assembly behaviors were studied using circular dichroism (CD) and transmission electron microscopy (TEM). A series of helical organic-inorganic hybrid silica nanotubes, methylene-silica, 1,2-ethylene-silica, 1,2-vinylidene-silica, 1,4-phenylene-silica and 4,4'-biphenylene-silica, were prepared using the self-assemblies of the amphiphiles as a template and 3-aminopropyltriethoxysilane as a co-structure-directing agent through a sol-gel method. It was shown in the CD spectra that the aromatic rings stacked in chiral within the backbones of 4,4'- biphenylene-silica. The morphology of 4,4'-biphenylene-silica and the stacking of the biphenyl group within the framework were controllable by tunning the reaction temperature, reaction time, pH, volume ratio of solvents and concentration. The handedness of the hybrid silica nanotubes and the stacking of the biphenyl group were pH- and concentration sensitvie. The formation of the helical structure was studied using field-emssion scanning electron microscopy and transmission electron microscopy. A cooperation self-assembly mechanism was revealed. Moreover, chiral mesoporous silica were prepared through a dual-templating approach using this chiral anionic amphiphile.