Chirality of Single‐Handed Twisted Titania Tubular Nanoribbons Prepared Through Sol‐gel Transcription

Abstract

Single-handed twisted titania tubular nanoribbons were prepared through sol-gel transcription using a pair of enantiomers. Handedness was controlled by that of the template. The obtained samples were characterized using field-emission electron microscopy, transmission electron microscopy, diffuse reflectance circular dichroism (DRCD), and X-ray diffraction. The DRCD spectra indicated that the titania nanotubes exhibit optical activity. Although the tubular structure was destroyed after being calcined at 700 °C for 2.0 h, DRCD signals were still identified. However, the DRCD signals disappeared after being calcined at 1000 °C for 2.0 h. The optical activity of titania was proposed to be due to chiral defects. Previous results showed that straight titania tubes could be used as asymmetric autocatalysts, indicating that titania exhibit chirality at the angstrom level. Herein, it was found that they also exhibit DRCD signals, indicating that there are no obvious relationships between morphology at the nano level and chirality at the angstrom level. The nanotube chirality should originate from the chiral defects on the nanotube inner surface. The Fourier transform infrared spectra indicated that the chirality of the titania was transferred from the gelators through the hydrogen bonding between N-H and Ti-OH.

Convenient chirality transfer from organics to titania: construction and optical properties

“…It was even found that several kinds of chiral features (e.g., lattice-chirality, shape-chirality) at different length-scales could simultaneously appear on the same chiral inorganic nanomaterial (e.g., ZnO, HgS). 15,36 In another example, 28 twisted TiO 2 nanoribbons were prepared by using organic assemblies as the templates. Both the as-obtained TiO 2 /organics hybrids and anatase TiO 2 aer calcinations showed the twisted morphologies on the nano-scale.…”

“…Generally, the synthetic chiral TiO 2 could be divided into two types according to their synthesis procedures: the rst one is the helix-shaped TiO 2 with various helix pitches from tens nm to several mm; the other is the TiO 2 with chiral cavities on the molecular scale prepared via molecular imprinting. For the helical TiO 2 , they are usually synthesized by the sol-gel process in the presence of helix-shaped templates, which included so templates (e.g., cholesterol gelator, lipid amphiphilic N-acylamino acids, trans-(1R,2R)-and trans-(1S,2S)-1,2-diaminocyclohexane derivatives, valinederived chiral cationic gelators) [24][25][26][27][28] and hard templates (e.g., helical carbon nanotubes, SiO 2 lms with a long-range chiral nematic structures). 29,30 Moreover, the glancing angle deposition (GLAD) (a kind of physical vapor deposition) has been also employed for the preparation of helical TiO 2 lms.…”

Helical Mesoporous Tantalum Oxide Nanotubes: Formation, Optical Activity, and Applications

“…Cationic and nonionic LMWGs are often used to transfer the morphologies of LMWGs to metal oxides , Metal oxide nanoparticles can be adsorbed on the surfaces of gel fibers through electrostatic interactions.…”

“…During the past two decades, metal oxides have been shaped into a variety of nanosized structures . Among these nanostructures, the tubular nanostructures are the most attractive owing to the cavity and larger surface area compared with nanofibers.…”

“…Although a variety of single‐handed helical silica nanotubes has been prepared using the self‐assemblies of LMWGs as templates, reports on the preparation of single‐handed helical metal oxide tubular nanostructures are rare. Only Ta 2 O 5 , TiO 2 , and ZrO 2 nanotubes or tubular nanoribbons have been reported. The handedness of the tubular nanostructures is controlled by that of the templates.…”