Diameter-Selective Sorting of Single-Walled Carbon Nanotubes Using π-Molecular Tweezers for Energy Materials

Single-walled carbon nanotubes (SWCNTs) have remarkable electrical properties, making them excellent candidate energy materials for applications, such as transistors and thermoelectric devices. However, as-prepared SWCNTs are mixtures of various chiral indices associated with different diameters, and this heterogeneity hinders their practical applications. Therefore, the development of a method for sorting SWCNTs according to the diameter is required. Here, we report one-pot diameter sorting of SWCNTs through noncovalent functionalization with π-molecular tweezers, which act as a structure-selective oligomeric dispersant for SWCNTs. The tweezers are capable of isolating (9,4) SWCNTs and (7,6) SWCNTs with diameters of ∼0.9 nm from as-prepared SWCNTs to a sorting ratio of 90%. This high-diameter selectivity originates from molecular wrapping of the π-molecular tweezers around the SWCNT sidewalls based on π–π and hydrophobic interactions. Our findings are promising not only in terms of developing a suitable SWCNT sorting methodology but also for understanding their molecular-level sorting mechanism.