Nanocalipers as novel molecular scaffolds for carbon nanotubes

We have been developing host–guest chemistry for separation of carbon nanotubes (CNTs) according to diameter, metallicity, and even handedness. The host molecules named “nanotweezers” consisting of a rigid core and two receptors were designed and applied to CNT separation. To apply this methodology for separation of a wider range of CNTs with better selectivity, “nanocalipers” have been designed, which include a core, two corners, and two receptors. In this review, we focus on “nanocalipers”, new host molecules next to the nanotweezers, from their molecular design and synthesis to CNT separation.