Carbon nanobelt fashioned at last

Decades before nanoscientists zapped graphite with an electrical discharge to make the first carbon nanotubes, synthetic chemists were trying to craft similar, smaller structures in their reaction flasks. But the belt-shaped compounds these chemists were trying to create entirely from fused benzene rings were tough to come by. Chemists observed one such structure fleetingly via mass spectrometry a decade ago, but no one has been able to synthesize and isolate enough of these carbon nanobelts for further study—until now. Kenichiro Itami, Yasutomo Segawa, and coworkers at Nagoya University managed to fashion a nanobelt out of 12 aromatic rings (shown) via a series of successive Wittig reactions followed by a nickel-catalyzed aryl-aryl coupling reaction (Science 2017, DOI: 10.1126/science.aam8158). Although they synthesized the nanobelt in only 0.2% overall yield, the Nagoya researchers made enough of it to get crystals for X-ray analysis. The crystal structure reveals that the bonds at the nanobelt’s equator have benzene-like bond lengths of about 1.4 Å, while the remaining bonds have single- and double-bond characters. The researchers believe the nanobelts could serve as seed molecules for making structurally well-defined carbon nanotubes.