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 (Ta₂O₅) nanotubes were prepared using a supramolecular templating approach. Field-emission scanning electron microscopy images showed that the handedness of the Ta₂O₅ nanotubes was controlled by that of the template organic self-assembly. Circular dichroism (CD) spectra revealed that the nanotubes exhibited optical activity. Because straight Ta₂O₅ nanotubes also exhibit optical activity, there is no relationship between the optical activity and handedness of the Ta₂O₅ nanotubes. The CD spectrum simulated using time-dependent density functional theory indicated that chiral point defects were responsible for the optical activity. It was also found that the chirality of Ta₂O₅ could be transferred to stacked poly(n-nonyl-2-methylpropylsilane).