Preparation Of Helical Carbonaceous Nanomaterials Using Carboxylic Acid Terminated Low-molecular-weight Gelators

Chiral carbon nanomaterials have attracted much attention owing to their potential applications in asymmetric catalysis, enantioseparation, electromagnetic wave absorption and stealth material. With the development of the preparation technologies for nanomaterials, carbonaceous nanomaterial with helical morphology became a hot topic due to the special properties. Herein, carbonaceous nanomaterials with different morphologies were prepared using carboxylic acid terminated low-molecular-weight gelators through supramolecular templating methods. The morphologies, architectures, and optical activity of them were characterized using field scanning electron microscope, transmission electron microscope, N2 adsorptions, powder X-ray diffraction, circular dichroism(CD) and diffuse re?ectance CD(DRCD). The main research works are shown as following:Firstly, for a better understanding of the origination of the optical activity, single-handed twisted carbonaceous tubular nanoribbons and single-layered nanoribbons were prepared at different ethanol/water volume ratios through a supramolecular templating method. The CD spectra indicated the twisted carbonaceous tubular nanoribbons exhibited the optical activity, however, the single-layered nanoribbons did not. The chirality is transferred from the organic self-assemblies to the inner surfaces of the 4,4′-biphenylene-bridged polybissilsesquioxane tubular nanoribbons and subsequently to those of the carbonaceous tubular nanoribbons. The results indicated that the optical activity was at the inner surfaces.Secondly, due to the spring-like carbon nanomaterials having the potential application in the field of electromagnetic wave absorption and optical devices, single-handed coiled carbonaceous tubular nanoribbons were prepared. DRCD spectra indicated that the carbonaceous tubular nanoribbons had optical activity.Finally, to study the formation mechanism of 3-aminophenol-formaldehyde resin nanotubes, 3-aminophenol-formaldehyde resin nanotubes were prepared using a pair of bolaamphiphiles and by changing the content of 3-aminophenol. The results indicated that the helical nanotubes are formed by the adsorption and polycondesation of 3-aminophenol-formaldehyde resin on the surfaces of the templates through electrostatic interactions and hydrogen bondings. After carbonization, the single-handed helical carbonaceous nanotubes were obtained. The CD spectra indicated that both the single-handed helical 3-aminophenol-formaldehyde resin nanotubes and the carbonaceous nanotubes exhibited optical activity.