Cholic acid tuning the binary surfactant system for one-step separation of the enantiomers of (5,4) carbon nanotubes

High -efficiency separation of the enantiomers of (5, 4) single -wall carbon nanotubes (SWCNTs) is of great importance for the property study and applications of SWCNTs in bioimaging, chiral molecule screening and detection due to their high photoluminescence quantum efficiency and short emission wavelength. In this work, we introduced a new surfactant cholic acid (HC) with high hydrophobicity that has high resolution selectivity in modulating the selective adsorption of smalldiameter SWCNTs in gel columns. With this technique, (5, 4) SWCNTs, which usually have few contents in raw mixture materials and undetectable due to their low growth efficiency, were highly selectively adsorbed in gel columns by tuning HC concentrations. Afterward, high -purity enantiomers of single-chirality (5, 4) SWCNTs were separated by the ternary surfactant system of sodium dodecyl sulfate, sodium cholate, and sodium deoxycholate to selectively desorb their enantiomers from gel columns. Based on their circular dichroism spectra, we further experimentally determined the exciton band structures of (5, 4) SWCNTs, which are distinctly different from the previous theoretical calculation results. These achievements not only provide an important material foundation for the applications of (5, 4) SWCNTs, but also give a deeper insight into the relationship between the chiral structures and intrinsic properties of SWCNTs.