Cooperativity Between Porosity and Phosphorus Content in Polyphosphamides for Improving Catalytic Appel Reactions

Area of Science:

• Materials Science
• Catalysis
• Polymer Chemistry

Background:

• Phosphamide-based organic polymers (POPs) show potential as flame retardants and heterogeneous catalysts.
• The redox-active -NH-P(O) moiety in POPs enables applications in CO2 reduction and water-splitting.
• Existing POPs require further optimization for enhanced catalytic efficiency.

Purpose of the Study:

• To synthesize a nitrogen-rich mesoporous POP.
• To investigate the catalytic performance of the synthesized POP in the Appel reaction.
• To compare the catalytic activity of the mesoporous POP with nonporous and porous analogues.

Main Methods:

• Synthesis of a nitrogen-rich mesoporous POP by covalently linking -NH-P(O) to a pyridine ring.
• Characterization of the POP, including BET surface area and phosphorus content.
• Evaluation of catalytic activity in the Appel reaction, determining the turnover number (TON) and substrate scope.

Main Results:

• The synthesized POP exhibits a BET surface area of 22 m²/g and 15.1% phosphorus content.
• The POP achieved a highest TON of 696 in the Appel reaction, significantly higher than PPA (462) and p-PPA (561).
• The material demonstrated broad substrate scope for bromo and chloro Appel products and confirmed sustainability over five cycles.

Conclusions:

• The enhanced catalytic performance of the mesoporous POP is attributed to its increased BET surface area.
• The cooperative effect of the redox-active phosphorus center and high porosity drives superior catalytic activity.
• The synthesized POP is a promising, sustainable heterogeneous catalyst for the Appel reaction.