Topological Control of Dual Protonic-Electronic Conduction in Metal-Organic Frameworks

Metal-organic frameworks (MOFs) with intrinsic dual proton-electron conductivity are highly desirable for energy conversion devices and chemical separation, yet merging these properties within a single crystalline phase remains a challenge. Here, we report two novel Mn(II)-based conjugated MOFs that share similar building blocks, but diverge into distinct topologies: a kagome lattice (kgm) and an unprecedented pseudo bex-d topology (Mn-HHTP-bex-d). These frameworks exhibit sharply contrasting conduction profile: Mn-HHTP-kgm demonstrates excellent electronic conductivity (8.4 × 10^-1 S cm^-1 at room temperature), but limited proton transport (3.6 × 10^-7 S cm^-1) at 98% relative humidity (RH), whereas the pseudo bex-d topology exhibits more balanced electronic conductivity (2.4 × 10^-5 S cm^-1) and proton conductivity (4.5 × 10^-5 S cm^-1 at 98% RH). Crystallographic and computational studies indicate that the efficient π-π stacking in kgm topology promotes charge delocalization and through-space charge transport for electrical conduction, while the pseudo bex-d topology leverages framework-incorporated water molecules and acetate moieties to establish efficient hydrogen-bonding networks for proton transport. This work highlights the critical role of topological control in modulating mixed-conduction properties and offers valuable insights for designing multifunctional MOFs for ambipolar devices, bioelectronics, and energy systems.