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.