Accelerated polymerization of N-carboxyanhydrides catalyzed by crown ether

The recent advances in accelerated polymerization of N-carboxyanhydrides (NCAs) enriched the toolbox to prepare well-defined polypeptide materials. Herein we report the use of crown ether (CE) to catalyze the polymerization of NCA initiated by conventional primary amine initiators in solvents with low polarity and low hydrogen-bonding ability. The cyclic structure of the CE played a crucial role in the catalysis, with 18-crown-6 enabling the fastest polymerization kinetics. The fast polymerization kinetics outpaced common side reactions, enabling the preparation of well-defined polypeptides using an alpha -helical macroinitiator. Experimental results as well as the simulation methods suggested that CE changed the binding geometry between NCA and propagating amino chain-end, which promoted the molecular interactions and lowered the activation energy for ring-opening reactions of NCAs. This work not only provides an efficient strategy to prepare well-defined polypeptides with functionalized C-termini, but also guides the design of catalysts for NCA polymerization. The recent advances in accelerated polymerization of N-carboxyanhydrides (NCAs) enrich the toolbox to prepare well-defined polypeptide materials. Here the authors use crown ethers to catalyze the polymerization of NCA initiated by conventional primary amine initiators in solvents with low polarity and low hydrogen-bonding ability.

Automated summary

Recent advances in accelerated polymerization of N-carboxyanhydrides (NCAs) have enriched the toolbox for preparing well-defined polypeptide materials. The use of crown ethers to catalyze NCA polymerization enables efficient preparation of functionalized polypeptides, while also guiding catalyst design.