Abstract

Nonbenzenoid carbon nanostructures provide a versatile platform for engineering metallic electronic states beyond conventional graphene-based materials. Building on our previous realization of a metallic biphenylene network and the atomically precise synthesis of nonbenzenoid biphenylene nanoribbons [1,2], I will present our recent studies of two metallic one-dimensional carbon systems that illustrate how transverse confinement governs the nature of metallicity.

The first system is an atomically precise carbon pentaheptite nanoribbon, CPHN 1, whose backbone is composed exclusively of fused pentagons and heptagons. Spatially resolved spectroscopy reveals a dispersive electronic band crossing the Fermi level, while tip-lifting transport measurements demonstrate robust conduction along finite ribbon segments. These results establish CPHN 1 as a one-dimensional covalent metal arising from its nonbenzenoid carbon framework.

In a substantially narrower metallic carbon ribbon, stronger transverse confinement and reduced electronic screening markedly enhance electron–electron interactions. The resulting electronic states depart from a conventional single-particle description and exhibit characteristic signatures of collective one-dimensional behaviour consistent with a Tomonaga–Luttinger liquid. Together, these systems reveal a confinement-driven evolution from band-like metallicity in a finite-width covalent nanoribbon to a strongly correlated quantum metal in the true one-dimensional limit.

 

References

[1] Q. Fan et al., “Biphenylene network: A nonbenzenoid carbon allotrope,” Science 372, 852–856 (2021). https://doi.org/10.1126/science.abg4509
[2] Q. Fan et al., “On-surface radical ring-opening polymerization produces ultralong poly(para-phenylene) for access to non-benzenoid carbon nanoribbons,” Nature Chemistry 18, 959–966 (2026). https://doi.org/10.1038/s41557-026-02092-y