We report a strategy for realizing tunable electrical conductivity in MOFs in which the nanopores are infiltrated with redox-active, conjugated guest molecules. This approach is demonstrated using thin-film devices of the MOF Cu3(BTC)2 (also known as HKUST-1) infiltrated with the molecule 7,7,8,8-tetracyanoquinododimethane (TCNQ). Tunable, air-stable electrical conductivity over six orders of magnitude is achieved, with values as high as 7 S/m. Spectroscopic data and first-principles modeling suggest unique conductivity mechanism occurring via TCNQ guest molecules bridging the binuclear copper paddlewheels in the framework leading to strong electronic coupling between the dimeric Cu subunits. These Ohmically conducting porous MOFs are prototypes for a novel class of materials that opens routes for entirely new applications.
Pub Type: Journals
Metal-organic framework, electrical conductivity, nanopores