Single-handed helical silica nanotubes were prepared according to the literature procedures,using the self-assemblies of a pair of chiral cationic low-molecular-weight gelators as the templates.A chirality indicator,4,4＇-bis（triethoxysilyl）-1,1＇-biphenyl,was developed to determine the chirality of the silica nanotubes.The chirality of the surfaces and the bulky walls of the silica nanotubes were understood from the twist of the biphenylene rings.
Helical 1,2-ethylene-silica nanofibers with lamellar mesopores on the surfaces and twisted rod-like mesopores inside were prepared according to literature procedures. After carbonization, helical carbon/ silica nanofibers with lamellar mesopores on the surfaces and twisted rod-like micropores inside were obtained. The morphologies and pore architectures of the carbon]silica nanofibers were characterized using transmission electron microscopy, field-emission scanning electron microscopy, powder X-ray diffraction and N2 sorptions. Although the mesopores inside shrank into micropores, the helical nanostructure remained. Moreover, several carbon/silica nanofibers with lamellar mesopores on the surfaces and concentric circular micropores inside were also obtained. After being calcined in air, helical silica nanofibers with lamellar mesopores on the surfaces and twisted rod-like micropores inside were produced as well.
Multilayered 1,2-ethylene-silica nanotubes were prepared with cetyltrimethylammonium bromide（CTAB） as a template and（S）-β-citronellol（CN） as a co-structure-directing agent.For a better understanding of the formation of this structure,the CN/CTAB molar ratio in the reaction mixtures was tuned.With increasing the CN/CTAB molar ratio,a hexagonal to lamellar phase trasformation was observed;and the morphologies of 1,2-ethylene-silica changed from rod to vesicle and then to tubular structure.CN droplets were proposed as the templates for the nanotubes.The obtained samples were characterized by means of X-ray diffraction,nitrogen sorption,field emission scanning electron microscopy and transmission electron microscopy.
Left-handed, coiled, 4,4＇-biphenylene bridged polybissilsesquioxane, tubular nanoribbons were prepared according to the published literature. After carbonization and removal of silica using HF aqueous solution, left-handed, coiled, carbonaceous, tubular nanoribbons were obtained. The left- handed, coiled, carbonaceous, tubular nanoribbons were characterized using field-emission scanning electron microscopy, transmission electron microscopy, powder X-ray diffraction, Raman spectropho- tometer, diffuse reflectance circular dichroism （DRCD）, and N2 adsorptions. Micropores were formed due to the removal of silica. The nitrogen BET surface area is 1727 m2/g. A broad, positive DRCD signal, identified at 400-800 rim, indicates the carbonaceous, tubular nanoribbons exhibit optical activity. The helical pitch is proposed to play an important role in the position of the DRCD signal.
Single-handed helical phenolic resin nanofibers were synthesized through a supramolecular templating approach using the supramolecular self-assemblies of a pair of chiral low-molecular-weight amphiphiles as the templates and 2,4-dihydroxybenzoic acid and formaldehyde as the precursors.The phenolic resin nanofibers were characterized using field-emission scanning electron microscopy,transmission electron microscopy and diffused reflection circular dichroism.The results indicated that the chirality of the supramolecular self-assemblies was successfully transferred to the phenolic resin nanofibers.The left- and right-handed helical phenolic resin nanofibers exhibited opposite optical activity.
Helical mesoporous silica nanorods were prepared using cetyltrimethylammonium bromide and achiral alcohols as the co-structure-directing agents. They were characterized using field-emission scanning electron microscopy, transmission electron microscopy, nitrogen sorptions, and small angle X-ray diffraction. The length of the silica nanorods increases with increasing the length of the alcohols. When n-heptanol and n-octanol were used, helical mesoporous silica nanorods with lamellar mesopores on the surfaces were obtained.
Yun Yue PuYi LiWei ZhuangMing ZhangBao Zong LiYong Gang Yang
