Localized Cation Unlocks Unique Activity–Selectivity Trends in Molecular Oxygen Reduction Catalysis

Abstract Redox-inactive ions are widely employed in heterogeneous and enzymatic catalysts to modulate reactivity through Lewis acid, elec-trostatic, and secondary coordination effects, yet molecular platforms that integrate these synergistic interactions within a unified design remain underexplored. The challenge lies in designing systems that harness these cooperative interactions for enhanced cata-lytic performance. Here we show a rationally designed porphyrin ligand (L1) that encapsulates diverse cations (Li+ to Sc3+), enabling precise electronic modulation through combined effects under homogeneous conditions. Spectroscopic and electrochemical analyses reveal charge-dependent perturbations across mono-, di-, and trivalent cations. In oxygen reduction catalysis, the iron complex (FeL1−Cl) unlocks unique activity-selectivity trends from unprecedented concerted electrostatic and coordination effects, achieving a four-electron pathway at significantly reduced overpotentials. The L1 framework provides a versatile blueprint for next-generation molecular catalysts that harness cooperative interactions to optimize reactivity across diverse transformations.