Extremozymes-Inspired Catalyst for Epoxide-Based Polymerization

Area of Science:

• Catalysis
• Materials Science
• Biomimetic Chemistry

Background:

• Enzyme-mimetic catalysis offers high-performance catalyst designs.
• Conventional enzyme designs face limitations in activity and robustness under non-physiological conditions.
• Hyperthermophilic enzymes provide a model for high-temperature catalysis.

Purpose of the Study:

• To develop an "extremozymes-inspired" design strategy for advanced catalysts.
• To construct a hexameric aluminum porphyrin catalyst mimicking extremozyme architecture.
• To evaluate the catalyst's performance in polymerization reactions.

Main Methods:

• Designed a hexameric aluminum porphyrin catalyst with a dimer-of-trimers architecture.
• Utilized geometric constraints for stable spatial arrangement and confined multisite catalysis.
• Tested the catalyst in propylene oxide (PO) homopolymerization and copolymerizations with phthalic anhydride (PA) and carbon dioxide (CO2).

Main Results:

• Achieved record-high turnover frequencies (TOFs) and high number-average molecular weights (Mn) at ppm-level catalyst loadings.
• PO homopolymerization: TOF = 8.1 × 10^5 h^-1, Mn = 1210 kg/mol.
• PO/PA copolymerization: TOF = 1.4 × 10^4 h^-1, Mn = 140.8 kg/mol.
• PO/CO2 copolymerization: TOF = 1.2 × 10^5 h^-1, Mn = 802.3 kg/mol.

Conclusions:

• Extremozyme-inspired design is a viable strategy for high-performance catalysts.
• The developed catalyst exhibits superior activity and produces polymers with high molecular weights.
• This work provides insights into designing robust and efficient biomimetic catalysts.