Modeling the Enzyme Specificity by Molecular Cages through Regulating Reactive Oxygen Species Evolution

Area of Science:

• Supramolecular Chemistry
• Catalysis
• Materials Science

Background:

• Mimicking enzyme active sites for specific catalysis is a significant challenge.
• Porous coordination cages (PCCs) offer tunable cavities and metal centers for catalytic applications.
• Controlling reactive oxygen species (ROS) generation pathways is crucial for selective oxidation reactions.

Purpose of the Study:

• To investigate the ability of porous coordination cages (PCCs) to mimic enzyme active sites for specific catalytic reactions.
• To explore how different metal centers within PCCs regulate reactive oxygen species (ROS) generation pathways.
• To demonstrate the application of PCCs in selective oxidation reactions by harnessing distinct ROS generation mechanisms.

Main Methods:

• Synthesis of porous coordination cages (PCCs) with varying metal centers (Zn, Ni, Co).
• Photo-induced oxidation experiments to study ROS generation pathways.
• Catalytic activity assessment of PCC-6-M (M=Zn/Ni/Co) in specific oxidation reactions.

Main Results:

• PCCs with Zn, Ni, and Co centers demonstrated distinct ROS generation pathways: Zn promoted singlet oxygen (¹O₂), Ni facilitated superoxide radical (O₂•⁻) formation, and Co generated carbonyl radicals.
• The specific ROS generation enabled selective catalytic conversions: PCC-6-Zn for thioanisole oxidation, PCC-6-Ni for benzylamine coupling, and PCC-6-Co for aldehyde autoxidation.
• The study provides fundamental insights into regulating ROS generation by supramolecular catalysts.

Conclusions:

• Porous coordination cages can effectively mimic enzyme active sites to achieve high specificity in catalytic reactions.
• The tunable metal centers in PCCs allow precise control over ROS generation pathways, leading to distinct catalytic outcomes.
• This work presents a novel approach for designing enzyme-inspired catalysts with tailored reactivity and specificity.