Surfactant-wrapped separation methods of metallic and semiconducting single-walled carbon nanotubes (SWCNTs) can result in large changes in intrinsic physical and chemical properties due to electronic interactions between a nanotube and a surfactant. Our approach to synthesize SWCNTs with an electronic feature relied on utilizing carbon nanorings, [n] cycloparaphenylenes ([n]CPPs), which are the fundamental unit of armchair type SWCNTs (a-SWCNTs) that possess a metallic feature without any surfactants. To obtain long tubular structures from [n]CPPs, the host-guest complexes formed with well-aligned [n]CPP hosts and various fullerene guests on a silicon substrate were pyrolyzed under an ethanol gas flow at a high temperature with focused-ultraviolet laser irradiation. The pyrolyzed [n]CPPs were observed to transform from nanorings to tubular structures with 1.5–1.7 nm diameters corresponding to the employed diameter of [n]CPPs. Our approach suggests that [n]CPPs are useful for structure-controlled synthesis of SWCNTs.

Abstract
 1. Introduction
 2. Experimental
  2.1. Synthesis of SWCNTs from [12]cycloparaphenylenes(CPPs)
  2.2. Structural analysis
  2.3. Computational analysis during the SWCNTgrowth process
 3. Results and Discussion
 4. Conclusions
 References

• Tomohiro Tojo(Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology) Corresponding Author
• Ryoji Inada(Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology)
• Yoji Sakurai(Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology)
• Yoong Ahm Kim(Department of Polymer Engineering, Chonnam National University) Corresponding Author