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

Integrating electrostatic and Lewis acid effects within a single molecular framework is a critically designed consideration central to the rational design of functional catalysts. Here, we report modular crown-porphyrin architectures that incorporate redox-inactive cations into programmable secondary coordination environments. This design enables systematic modulation of local electric fields, revealing charge-dependent perturbations across mono-, di-, and tri-valent cations through spectroscopic and electrochemical analyses. In oxygen reduction catalysis, the corresponding iron complexes (FeL1-Cl) display tunable reactivity landscapes arising from the interplay of electrostatic and Lewis acid effects. These results provide a framework for the design of cation-responsive molecular architectures in which cooperative noncovalent interactions can be leveraged to influence catalytic outcomes, as illustrated here for oxygen reduction reaction.