The two-dimensionally connected metal-organic frameworks (MOFs) Ni(HIB) and Cu(HIB) (HIB = hexaiminobenzene) are bulk electrical conductors and exhibit ultraviolet-photoelectron spectroscopy (UPS) signatures expected of metallic solids. Electronic band structure calculations confirm that in both materials the Fermi energy lies in a partially filled delocalized band. Together with additional structural characterization and microscopy data, these results represent the first report of metallic behavior and permanent porosity coexisting within a metal-organic framework.

Thermoelectric devices utilize waste heat to generate electricity or consume electricity to transfer heat. Sun et al. describe high electrical conductivity and ultralow thermal conductivity in the nanoporous material Ni 3 (HITP) 2 , improve the record of thermoelectric figure of merit in metal-organic frameworks (MOFs), and demonstrate that MOFs are promising candidates for thermoelectrics.