Redox Control in a Conducting MOF through Coupled Electronic–Vibronic Effects

High Resolution Image Download MS PowerPoint Slide Redox control in electrically conducting metal–organic frameworks (MOFs) requires understanding how intercalated cations reshape both electronic structure and lattice thermodynamics. In the nominal A 2 -Mn-DOBDC anionic framework (A = Li +, Na +, K + ), redox potentials and electronic conductivities follow K < Li < Na, contradicting an electrostatic polarization model. Finite-temperature free-energy partitioning shows competing contributions: Δ F EL (electronic term) decreases along Li > Na > K, whereas Δ F VIB (vibrational term) increases along Li < Na < K, producing a maximum stabilization that favors Na and rationalizes the nonintuitive potential ordering. FTIR band shifts track cation-induced systematic mode shifts consistent with cation-dependent vibrational reorganization, and DFT vibrational densities of states with Helmholtz free energies reproduce Δ F VIB trends. Mixed-valence charge transfer with cation-modulated electronic coupling accounts for the conductivity ordering. Na 2 -Mn-DOBDC delivers a median discharge voltage of ∼3.0 V vs Na + /Na while retaining measurable electronic conductivity, providing a general electronic–vibronic route to tune redox energetics in conducting MOFs.