Extremozymes-Inspired Catalyst for Epoxide-Based Polymerization

Enzyme-mimetic catalysis is widely recognized as an effective approach to developing high-performance catalysts. However, in many reactions conducted under conditions far from physiological, designs based on conventional enzymes often limit both activity and robustness. Inspired by hyperthermophilic enzymes that maintain high activity at temperatures nearing 100 °C, we propose an "extremozymes-inspired" design strategy and construct a hexameric aluminum porphyrin catalyst featuring a dimer-of-trimers architecture. By leveraging the geometric constraints imposed by covalent and noncovalent interactions between porphyrins, the catalyst forms two trigonal-pyramidal cavities, thereby replicating both the stable spatial arrangement and the confined multisite catalytic microenvironment characteristic of extremozymes. In propylene oxide (PO) homopolymerization and its copolymerizations with phthalic anhydride (PA) and carbon dioxide (CO2), respectively, the extremozymes-mimetic catalyst achieves record-high turnover frequencies (TOFs) while producing polymers with high number-average molecular weights (Mn) at ppm-level loadings: PO homopolymerization (TOF = 8.1 × 105 h-1, Mn = 1210 kg/mol); PO/PA copolymerization (TOF = 1.4 × 104 h-1, Mn = 140.8 kg/mol); and PO/CO2 copolymerization (TOF = 1.2 × 105 h-1, Mn = 802.3 kg/mol). This study demonstrates the potential of using extremozymes as templates to develop high-performance catalysts and offers new insights into the design of biomimetic catalysts.