Single-Site Pd Regulated by π-π Stacking for High-Selectivity Cyclopropanation Reaction

Area of Science:

• Catalysis
• Materials Science
• Organic Chemistry

Background:

• Cyclopropane-based high-energy fuels offer high energy density but their synthesis is difficult.
• The high strain of cyclopropane rings hinders the formation of metal-carbene intermediates, leading to poor catalytic selectivity.
• Developing efficient and selective synthetic methods for these fuels is crucial.

Purpose of the Study:

• To develop a single-site palladium catalyst for the precise synthesis of multicyclopropane-based high-energy fuels.
• To investigate the role of π-π stacking interactions between a palladium complex and graphene in enhancing catalytic performance.
• To improve the selectivity of cyclopropanation reactions.

Main Methods:

• Rational design of a palladium-organic complex integrated with graphene.
• Utilizing π-π stacking interactions to modulate metal-support interactions and active site adsorption.
• Characterization of catalyst performance in cyclopropanation reactions.

Main Results:

• The π-π stacking significantly enhanced the electrophilicity of palladium, promoting the formation of Pd═C carbene intermediates.
• Enhanced adsorption of active centers and intermediates was observed due to π-π stacking.
• Achieved a cyclopropanation reaction selectivity of 80.5%, nearly doubling the selectivity observed without π-π stacking.

Conclusions:

• π-π stacking is an effective strategy for enhancing the electrophilicity of palladium catalysts and improving adsorption of intermediates.
• This approach provides a viable method for precise synthesis of multicyclopropane-based high-energy fuels.
• The study demonstrates the utility of noncovalent π-π interactions in controlling C-C coupling reaction selectivity.