Decoding Surface Electron Density-Reactivity Relationship in Ni-Porous Organic Polymer Catalyst for Cyclohexene...

Area of Science:

• Materials Science
• Catalysis
• Green Chemistry

Background:

• Efficient and sustainable heterogeneous catalysts are crucial for advancing green oxidation chemistry.
• Metalated porous organic polymers offer tunable properties for catalytic applications.

Purpose of the Study:

• To synthesize and characterize a novel Ni-salphen-derived metalated porous organic polymer (Ni@CAB).
• To evaluate the catalytic performance of Ni@CAB in aerobic oxidation reactions.
• To establish surface electron density as an activity descriptor for oxidation catalysts.

Main Methods:

• Friedel-Crafts alkylation for polymer synthesis.
• 2D solid-state NMR, XPS, synchrotron-based XAS, and electron microscopy for characterization.
• Density Functional Theory (DFT) calculations for mechanistic insights.

Main Results:

• Ni@CAB possesses an amorphous porous architecture with uniformly dispersed Ni-N2O2 active sites.
• The catalyst exhibits enhanced Lewis acidity due to reduced surface electron density at Ni sites.
• Exceptional performance in aerobic allylic oxidation of cyclohexene: complete conversion, high selectivity, and excellent recyclability without Ni leaching.

Conclusions:

• Ni@CAB is a highly effective and sustainable heterogeneous catalyst for green oxidation chemistry.
• Surface electron density is a key descriptor for predicting and enhancing catalytic activity.
• Rationally engineered metalated porous polymers hold significant promise for sustainable catalysis.