Atomic-Precision Non-van der Waals 2D Structures: Superconductivity in π-d Conjugated Coordination Polymers

Two-dimensional conjugated coordination polymers (2D c-CPs) exhibit exceptional charge transport properties. Among them, copper-based benzenehexathiol coordination polymer (Cu-BHT) is a rare superconductor. However, the precise atomic structure of Cu-BHT remains elusive, hindering the understanding of the origin of superconductivity in 2D c-CPs. Here, single crystals of Cu3BHT with the high crystallinity have been achieved, revealing a quasi-2D kagome structure with non-van der Waals interlayer Cu-S covalent bonds. Cu3BHT single crystal exhibits intrinsic metallic behavior, with conductivity reaching 10E3 S/cm at 300 K and 10E4 S/cm at 2 K. Notably, superconductivity in Cu3BHT crystals was observed for the first time at 0.25 K, attributed to the enhanced electron-electron interactions and electron-phonon coupling induced by non-van der Waals 2D structures. The discovery of this clear correlation between atomic-precise crystal structure and electrical properties lays a crucial foundation for the emergence of new superconductor CPs, aiming for revolutionizing the future quantum devices.