Cylindrical and Conical Conjugated Nanobelts by Longitudinal Extension of Cycloparaphenylene and Their Double-Walled Assembly

Constructing carbon nanotubes and related segments with atomic precision remains challenging, despite significant advances, including cycloparaphenylene (CPP), carbon nanobelts, and phenine nanotubes. Here, we report three conjugated nanobelts (NB1–NB3) constructed by longitudinal π-extension of CPP with rings of the same, smaller, or larger size. Each nanobelt comprises three fused aromatic units bridging two axial CPP rings, which mediate the intermolecular assembly. NB1–NB3 have a delocalized electronic structure, showing largely red-shifted emission. The smaller NB2 can insert into NB3 to form a stable double-walled assembly (NB2⊃NB3), which exhibits energy transfer with nearly 100% efficiency.