Cooperativity in Shape-Persistent Bis-(Zn-salphen) Catalysts for Efficient Cyclic Carbonate Synthesis under Mild
Yeqing Xia1, Shixiong He1, Junhui Bao1
1Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong, China.
Inorganic Chemistry
|November 22, 2022
Summary
New dinuclear zinc catalysts with rigid backbones efficiently convert CO2 and epoxides into cyclic carbonates. These catalysts exhibit enhanced activity and cooperative effects, paving the way for greener chemical synthesis.
Area of Science:
- Coordination Chemistry
- Catalysis
- Green Chemistry
Background:
- Development of efficient catalysts for CO2 utilization is crucial for sustainable chemistry.
- Metal-salphen complexes are known catalysts, but enhancing their cooperative effects remains a challenge.
Purpose of the Study:
- To design and synthesize conformationally rigid (Zn-salphen)2 complexes.
- To investigate their catalytic activity in the coupling of CO2 with epoxides.
- To explore cooperative effects in dinuclear zinc catalysis.
Main Methods:
- Synthesis of planar-bridged (Zn-salphen)2 complexes.
- Catalytic testing for CO2 cycloaddition with epoxides.
- In situ ReactIR spectroscopy and Density Functional Theory (DFT) calculations.
Main Results:
- Selected dibenzofuran-bridged complexes show significantly higher activity than mononuclear analogues.
- High turnover frequencies (up to 29,000 h-1) achieved under optimized conditions.
- Kinetic studies and DFT calculations reveal intramolecular rate components and cooperative pathways.
Conclusions:
- Conformationally rigid dinuclear zinc catalysts demonstrate strong evidence of cooperative reactivity.
- The geometric constraints enhance catalytic performance for cyclic carbonate production.
- These findings offer a promising route for efficient CO2 valorization.
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