Scalable, Divergent Synthesis of a High Aspect Ratio Carbon Nanobelt

Carbon nanobelts are molecules of high fundamental and technological interest due to their structural similarity to carbon nanotubes, of which they are molecular cutouts. Despite this attention, synthetic accessibility is a major obstacle, such that the few known strategies offer limited structural diversity, functionality, and scalability. To address this bottleneck, we have developed a new strategy that utilizes highly fused monomer units constructed via a site-selective [2 + 2 + 2] cycloaddition and a high-yielding zirconocene-mediated macrocyclization to achieve the synthesis of a new carbon nanobelt on large scale with the introduction of functional handles in the penultimate step. This nanobelt represents a diagonal cross section of an armchair carbon nanotube and consequently has a longitudinally extended structure with an aspect ratio of 1.6, the highest of any reported nanobelt. This elongated structure promotes solid-state packing into aligned columns that mimic the parent carbon nanotube and facilitates unprecedented host–guest chemistry with oligo-arylene guests in nonpolar solvents.