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A 2024 study found that bias-induced charging can raise the measured conductance of certain porphyrin molecular junctions to the conductance quantum. That result—reported for custom molecules bridged between gold electrodes—is what the headline “no resistance” describes. It does not demonstrate a bulk, zero-resistance wire or a practical electronic component.
What the researchers measured
In “Ballistic Conductance through Porphyrin Nanoribbons,” published in the Journal of the American Chemical Society in 2024, researchers tested edge-fused porphyrin nanoribbons in single-molecule junctions. The series included molecules with up to eight nickel-porphyrin units; its longest members reached 7.1 nm. Trimethylsilyl alkyne end groups served as precursor anchor groups for gold electrodes. The team used scanning tunnelling microscope break-junction (STM-BJ) measurements to characterize electron transport. JACS paper.
How conductance reached 1 G₀
With gold-acetylide contacts, the study reported low-bias conductance as high as 10⁻² G₀. Under applied bias, charging the molecules in situ shifted the alignment of their frontier orbitals—the energy levels involved in electron transport. In the resulting high-conductance states, measured conductance reached 1 G₀, which the paper gives as 77.5 μS and relates to a current of 20 μA.
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The researchers also observed conductance-voltage traces with peaks near zero bias. They interpreted these as evidence that a molecular energy level was resonant with the electrodes’ Fermi level. The effect was most pronounced for longer molecules, which had smaller HOMO–LUMO gaps. These numbers describe the particular molecular-junction experiments, not specifications for a usable wire or device.
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What “no resistance” does—and does not—mean
The conductance quantum, G₀, is a benchmark for electron transmission through a sufficiently well-coupled transport channel. Reaching 1 G₀ in a charged molecular junction indicates very high transmission under that experiment’s conditions. It is not equivalent to proving that a macroscopic material has literally zero electrical resistance in ordinary use.
The paper’s conclusion also reports that low-bias transport remained suppressed relative to an ideal system. The headline is therefore shorthand for the high-conductance state observed after molecular charging—not evidence of a bulk superconductor, a room-temperature zero-resistance wire, or a commercially available material. Read the study; the phrase appeared in a Chemistry World report published on 13 March 2024.
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How this differs from porphyrin-fused graphene ribbons
A separate 2024 study, “Porphyrin-fused graphene nanoribbons,” examined a different material: a solution-synthesized hybrid nanoribbon. It reported high local charge mobility measured with ultrafast optical-pump terahertz-probe spectroscopy, along with prototype single-nanoribbon field-effect and single-electron transistor devices. Those mobility and device findings do not belong to the STM-BJ study of edge-fused porphyrin molecular junctions. Nature Chemistry paper.
| Study | Material and scale | Measurement or result |
|---|---|---|
| “Ballistic Conductance through Porphyrin Nanoribbons” (JACS, 2024) | Edge-fused porphyrin molecular wires; single-molecule junctions, up to 7.1 nm and eight nickel-porphyrin units | STM-BJ conductance; charging under bias produced states reaching 1 G₀ |
| “Porphyrin-fused graphene nanoribbons” (Nature Chemistry, 2024) | Solution-synthesized porphyrin-fused graphene nanoribbons | Terahertz measurement of local charge mobility and prototype transistor devices |
Why the result matters
The study shows how molecular structure, electrode contacts, and charge state can combine to produce near-quantum conductance in a molecular-scale junction. Its significance is a measured transport effect under specialized laboratory conditions, not a ready-made route to resistance-free wiring. The experiments do not establish how such molecules would perform in practical circuits or at larger scales.
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