Enhancing electronic conductivity and solvent accessible porosity via oxidative deinsertion in a vanadium catecholate...

Three-dimensional metal-organic frameworks (MOFs) that combine high electronic conductivity with porosity remain rare because the structural features that promote charge transport often compromise porosity. Here, we report a redox-active three-dimensional vanadium catecholate framework [(CH₃)₂NH₂]_2.5V(HOTP) (HOTP = 2,3,6,7,10,11-hexaoxidotriphenylene), an anionic MOF that is charge-balanced with [(CH₃)₂NH₂]⁺ ions occupying the pores. Controlled topotactic oxidation using thianthrenium hexafluorophosphate enables the stepwise deinsertion of these charge-balancing cations, yielding five distinct oxidized phases. Spectroscopic analyses reveal that both the vanadium centers and HOTP linker participate in the oxidation process, generating mixed-valence structures with Robin-Day class II/III delocalization across both metal and ligand components. Progressive oxidation and cation removal produce a dramatic enhancement in charge transport, culminating in an increase in electronic conductivity of nearly five orders of magnitude from ∼10^-6 S cm^-1 in the unoxidized phase to 0.4(2) S cm^-1 in the most oxidized phase, accompanied by near-complete removal of the cation from the pores. These results are a rare example of a porous framework in which electronic conductivity increases concomitantly with pore-vacating cation deinsertion, providing a strategy for reconciling electronic conductivity and pore accessibility in MOFs.