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The TaO of nanotubes: Single‐handed helical Ta2O5 nanotubes with mesopores in the walls were prepared using the self‐assemblies of the low‐molecular‐weight gelators as the templates. The handedness of the Ta2O5 nanotubes was controlled by organic self‐assemblies.

Single-handed helical silica nanotubes containing chiral organic self-assemblies were prepared by using a supramolecular templating approach. After carbonization and the removal of the silica, single-handed helical carbonaceous nanotubes that contained twisted carbonaceous nanoribbons were obtained. It is believed that the nanotubes formed as a result of the adsorption of low-molecular-weight gelators. The twisted nanoribbons were formed because of the carbonization of the organic self-assemblies. The samples were characterized by using field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Raman spectroscopy, and circular dichroism. For the samples carbonized at 900 °C for 3.0 h, a partially graphitized structure was identified. The circular dichroism (CD) spectra indicated that the twisted nanoribbons exhibited optical activity. The CD spectrum was simulated by using time-dependent density functional theory. The results suggested that the CD signals originated from the chiral stacking of aromatic rings.

a b s t r a c tTitania nanoparticles have attracted much attention for their application in catalysis. Over the last few decades, studies have shown that their morphology can be carefully controlled. However, reports on the preparation of helical titania nanotubes are rare. Here, a pair of valine-derived chiral cationic gelators were synthesized, which could self-assemble into helical nanofibers in ethanol and isopropanol. Single-handed helical titania nanotubes were prepared using a sol-gel transcription approach, using the self-assembly of the gelators as a template. The results indicated that the handedness of the titania nanotubes was controlled by that of the organic self-assembled structures. Transmission electron microscopy images indicated that the nanotubes were constructed from nanocrystals. Wideangle X-ray diffraction patterns indicated that the nanocrystals were anatase. Because the space group of anatase phases is chiral, the titania nanotubes have the potential to be used as asymmetric catalysts, and chirality sensors.

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