Current methods of synthesizing single-walled carbon nanotubes(SWNTs)result in racemic mixtures that have impeded the study of left-and right-handed SWNTs.Here we present a method of isolating different SWNT enantiome...Current methods of synthesizing single-walled carbon nanotubes(SWNTs)result in racemic mixtures that have impeded the study of left-and right-handed SWNTs.Here we present a method of isolating different SWNT enantiomers using density gradient ultracentrifugation.Enantiomer separation is enabled by the chiral surfactant sodium cholate,which discriminates between left-and right-handed SWNTs and thus induces subtle differences in their buoyant densities.This sorting strategy can be employed for simultaneous enrichment by handedness and roll-up vector of SWNTs having diameters ranging from 0.7 to 1.5 nm.In addition,circular dichroism of enantiomer refined samples enables identification of high-energy optical transitions in SWNTs.展开更多
基金The authors thank M.S.Arnold for helpful discussions and preliminary measurements.This work was supported by the U.S.Army Telemedicine and Advanced Technology Research Center(DAMD17-05-1-0381)the National Science Foundation(DMR-0520513,EEC-0647560,and DMR-0706067)A Natural Sciences and Engineering Research Council of Canada Postgraduate Scholarship(A.A.Green)and an Alfred P.Sloan Research Fellowship(M.C.Hersam)are also acknowledged.This work made use of instruments in the Keck-II facility of the NUANCE Center and the Keck Biophysics Facility at Northwestern University.The NUANCE Center is supported by NSF-NSEC,NSF-MRSEC,Keck Foundation,the State of Illinois,and Northwestern University.
文摘Current methods of synthesizing single-walled carbon nanotubes(SWNTs)result in racemic mixtures that have impeded the study of left-and right-handed SWNTs.Here we present a method of isolating different SWNT enantiomers using density gradient ultracentrifugation.Enantiomer separation is enabled by the chiral surfactant sodium cholate,which discriminates between left-and right-handed SWNTs and thus induces subtle differences in their buoyant densities.This sorting strategy can be employed for simultaneous enrichment by handedness and roll-up vector of SWNTs having diameters ranging from 0.7 to 1.5 nm.In addition,circular dichroism of enantiomer refined samples enables identification of high-energy optical transitions in SWNTs.
