Optical Resolution of SWNTs through Extraction with Chiral Diporphyrin Nanotweezers

摘要

Chiral single-walled carbon nanotubes (SWNTs) have left- and right-handed helical structures (M and P, respectively, according to the IUPAC nomenclature). In this paper, optically active SWNTs were obtained through preferential extraction of (M)- or (P)-SWNTs with 2,6-pyridylene-bridged chiral diporphyrins 1. In the circular dichroism (CD) spectra, the SWNTs extracted with 1 exhibit much larger intensity than those extracted with 1,3-phenylene-bridged chiral diporphyrins 2, indicating an improved chiral discrimination ability of 1. Especially, (6,5) SWNTs display the most intensified CD signals among the SWNTs extracted with 1. In addition, the SWNT extraction ability of 1 has been shown to be considerably enhanced in comparison to 2. These improved discrimination and extraction abilities of 1 are attributed to the formation of its more stable SWNT complex.