Figure. High-pressure topochemical polymerization strategy for ultra-long sheathed single-metal-atom chains.

Supported by the National Natural Science Foundation of China (Grant Nos. 22022101, 12574019, 22488101, 22325503), a research team led by Researcher Li Kuo at the Center for High Pressure Science and Technology Advanced Research in Beijing, together with collaborating institutions, has made progress in the synthesis of single-metal-atom chains. Their work, titled "Ultralong sheathed single-metal-atom chains synthesized under high pressure", was published online in Science on August 20, 2026. The paper is available at: https://www.science.org/doi/10.1126/science.aeg0028.

Single-metal-atom chains are one-dimensional structures formed by the linear arrangement of metal atoms. They can be regarded as metallic wires with the smallest possible diameter and serve as ideal model systems for studying one-dimensional condensed matter physics effects, holding promising application prospects in nanoelectronics, low-dimensional magnetism, catalysis, and other fields. However, bare single-metal-atom chains are highly prone to structural reconstruction, and conventional synthesis methods cannot simultaneously achieve long chain length, high structural stability, and scalable preparation. These factors has limited further progress in this field.

To address this challenge, the research team proposed a high-pressure solid-state topochemical polymerization strategy. Using β-phase copper phthalocyanine as a precursor, they employed pressure to modulate the molecular packing distance, driving topochemical polymerization of the peripheral aromatic rings to form a carbon sheath with a diamond-like structure. This sheath encapsulated ultralong copper single-atom chains within, and the overall structure remained nearly fully preserved after pressure release. At 40 GPa, milligram-scale of this material was synthesized. The resulting product exhibited one-dimensional antiferromagnetic coupling and pronounced electrical conductivity anisotropy. Using an acid-assisted ultrasonic exfoliation method, the team successfully exfoliated the crystals to obtain individual metal-atom chains wrapped in carbon sheaths, with the length exceeding 1 micrometer and more than 4,000 copper atoms arranged continuously.

The high-pressure solid-state topochemical polymerization strategy developed in this study has been validated across multiple metal phthalocyanine systems, establishing a synthesis platform for ultralong and stable single-metal-atom chains that can be prepared in batch and exfoliated as individual chains. This work expected to provide new candidate materials for spintronics, atomic-scale devices, electrocatalysis, and other fields.