Chiral defects on single-handed helical Ta₂O₅ nanotubes prepared using a supramolecular templating approach

Abstract

Recently, single-handed helical metal oxide nanotubes with optical activity have attracted much attention.They can be used as asymmetric catalysts. Herein, single-handed helical tantalum oxide (Ta 2 O 5 ) nanotubes were prepared using a supramolecular templating approach. Field-emission scanning electron microscopy images showed that the handedness of the Ta 2 O 5 nanotubes was controlled by that of the template organic self-assembly. Circular dichroism (CD) spectra revealed that the nanotubes exhibited optical activity.Because straight Ta 2 O 5 nanotubes also exhibit optical activity, there is no relationship between the optical activity and handedness of the Ta 2 O 5 nanotubes. The CD spectrum simulated using timedependent density functional theory indicated that chiral point defects were responsible for the optical activity. It was also found that the chirality of Ta 2 O 5 could be transferred to stacked poly(n-nonyl-2methylpropylsilane).

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.…”

“…Right‐ and left‐handed helical Ta 2 O 5 nanotubes have been prepared using LL‐ 4 and DD‐ 4 , respectively (Figure ) . Thinner nanotubes were also identified, which were straight.…”

“…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.…”

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

“…The interest has been continuously extended to other inorganic nanomaterials such as Si, ZrO 2 , ZnO, CuO, Y 2 O 3 , Ta 2 O 5 , Ln(OH)CO 3 and Lu 2 Si 2 O 7 . [13][14][15][16][17][18][19][20] Undoubtedly, these research studies will contribute to the development of the scope of chirality beyond the traditional organic chemistry.…”