Optical Activity Of Helical Resin Nanotubes And Carbonaceous Nanotubes Prepared Using Templating Approaches

DNA and proteins in living entities are chiral, which means a lot to the origin and succession of life. Research on optical activity of chiral materials can supply more applications in electronics, optics, asymmetric catalysis and enantiomer separation. Templating approaches are efficient to prepare chiral nanomaterials, which are able to control the morphologies and sizes of nanomaterials exactly and to characterize whether the samples are optical by circular dichroism（CD） and ultraviolet（UV） spectra. Then we can determine the origin of chirality. Therefore, the following work should be carried out.Firstly, we used a pair of bola-type hexamethylene diamine acylamino derivatives as templates, 3-aminophenol and formaldehyde as resin precursors, that successfully prepared single-handed helical 3-aminopheol formaldehyde resin nanotubes at the nano level, while using m-phenylene diamine to replace 3-aminophenol to react with the formaldehyde, straight m-phenylene diamine formaldehyde resin nanotubes at the nano level could be obtained. Circular dichroism（CD） results indicated that the resin nanotubes were with optical activity, which indicated that by using chiral amphiphiles as the templates, resin nanotubes with optical activity at the angstrom level could be obtained through supramolecular templating approach, there is no relationship between chirality at the nano level and that at the angstrom level. The origin of chirality is amphiphilic supramolecular assemblies at the atmosphere of solvents. Supramolecular templating approach can transfer chirality.Secondly, we used helical silica nanotubes which were prepared through supramolecular templating approach as a hard template, by adding tetrabutyl titanate and glucosamine to make them coated on the surface of the silica nanotubes at the condition of stirring, helical SiO₂@TiO₂@C composite structure could be obtained. Then we changed helical silica nanotubes with helical polybissilsesquioxane nanotubes to coat titanium dioxide on the surface of the hard template. Additionally, we utilized helical resin nanotubes as a hard template to coat titanium dioxide on the surface of the nanotubes, carbonization was carried out to obtain carbonaceous nanotubes. Helical titanium dioxide nanotubes could be obtained after removing the hard templates. Samples were characterized by using diffuse reflectance circular dichroism（DRCD） and diffuse reflectance ultra violet（DRUV）, which indicated that the as-prepared materials were with optical activity. Hard templating approach can transfer chirality, the chirality originates from supramolecular imprinting of the hard templates, which transfers from the supramolecular assemblies.