A Double‐walled Noncovalent Carbon Nanotube by Columnar Packing of Nanotube Fragments

Abstract Herein, we report the synthesis of double‐walled noncovalent carbon nanotubes (CNTs) through host–guest complexation of nanotube fragments and tube‐forming crystal engineering. As the smallest fragment of double‐walled CNTs, a host–guest complex of perfluorocycloparaphenylene (PFCPP) and carbon nanobelt (CNB) was synthesized by mixing them in solvents. The immediate complexation of the PF[12]CPP⸧(6,6)CNB complex with a remarkably high association constant ( K a ) of 2×10 5 L/mol was observed. Time‐dependent 1 H NMR and thermogravimetry measurements revealed that the stability of (6,6)CNB was significantly improved by encapsulation. X‐ray crystallography confirmed the robust belt‐in‐ring structure of this complex. As indicated by the short distance between PF[12]CPP and (6,6)CNB (2.8 Å), intermolecular orbital interactions exist between the belt and the ring, which were further supported by theoretical calculation and phosphorescence quenching experiments. While the PF[12]CPP⸧(6,6)CNB complex adopts various crystal packing structures, chloroform was discovered to be a magic “glue” solvent inducing one‐dimensional alignment of the PF[12]CPP⸧(6,6)CNB complex to build an unprecedented double‐walled noncovalent CNT structure.