Enhanced Electrical Conductivity by the Heavy Chalcogen Effect in Metal-Organic Frameworks

Establishing effective strategies to impart electrical conductivity to metal-organic frameworks (MOFs) provides new opportunities for advancing research in electronic materials. In this study, we develop a heavy chalcogen incorporation strategy by constructing a new family of isoreticular two-dimensional conductive MOFs, Cu-X-HHS, through the interconnection of Cu ions with three hexahydroxysumanene (HHS) ligands which are embedded chalcogen (X) atoms, including sulfur (S), selenium (Se), and tellurium (Te). Cu-X-HHS MOFs have an infinitely extended wavy and honeycomb network structure. A substantial enhancement in electrical conductivity is observed with increasing atomic number of the incorporated chalcogenides, among which Cu-Te-HHS exhibits an impressive room temperature conductivity of 3.21 S cm^-1, 10,000 times higher than the S-containing analog. Mechanism study reveals that the chalcogen atoms with gradually decreased electronegativity and increased atomic radii affect the frontier orbital matching between the ligand and the Cu ions, as well as the interlayer interaction in the Cu-X-HHS MOFs.