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

Area of Science:

• Catalysis
• Supramolecular Chemistry
• Materials Science

Background:

• Rational catalyst design requires integrating electrostatic and Lewis acid effects.
• Crown-porphyrin architectures offer a modular platform for controlling molecular environments.

Purpose of the Study:

• To develop modular crown-porphyrin architectures for systematic modulation of local electric fields.
• To investigate the influence of cation charge on catalytic activity in iron complexes.
• To establish a framework for cation-responsive molecular design in catalysis.

Main Methods:

• Synthesis of modular crown-porphyrin architectures.
• Incorporation of redox-inactive cations into secondary coordination environments.
• Spectroscopic and electrochemical analyses to probe charge-dependent perturbations.
• Evaluation of iron complexes in oxygen reduction catalysis.

Main Results:

• Systematic modulation of local electric fields achieved by varying cation charge (mono-, di-, tri-valent).
• Demonstration of charge-dependent perturbations through spectroscopic and electrochemical data.
• Tunable oxygen reduction catalysis observed for iron complexes (FeL1-Cl) due to combined electrostatic and Lewis acid effects.
• Evidence of cooperative noncovalent interactions influencing catalytic outcomes.

Conclusions:

• Crown-porphyrin architectures provide a versatile platform for designing cation-responsive catalysts.
• The interplay of electrostatic and Lewis acid effects is crucial for tuning catalytic reactivity.
• This work offers a framework for leveraging noncovalent interactions to optimize catalytic performance, particularly for oxygen reduction reactions.