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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >NAM-TMS Mechanism of alpha-Amino Acid N-Carboxyanhydride Polymerization: A DFT Study
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NAM-TMS Mechanism of alpha-Amino Acid N-Carboxyanhydride Polymerization: A DFT Study

机译：α-氨基酸正羧酸酐聚合的NAM-TMS机制：DFT研究

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摘要

The normal amine mechanism via the proton-transfer route (NAM-H) is widely accepted for the synthesis of polypeptides with nonionic initiators. Besides proton transfer, the trimethylSily1 (TMS) group transfer process has been found in living/controlled polymerization initiated by N-TMS amine in experiments, but the corresponding mechanism has never been proposed. In this work, we employed density functional theory (DFT) with the solvation model to investigate the details, of the TMS-transfer mechanism) defined as NAM-TMS, for the ring opening polymerization of alpha-amino acid N-carboxyanhydride. The TMS transfer process of NAM-TMS is thermodynamically more favored than the NAM-H mechanism according to the lower addition energy barrier observed. The rate determining step (RDS) in NAM-TMS is the decarboxylation step, i.e., the release of CO2, rather-than carbonyl addition in NAM-H because of the low dipole stable precursor enlarged energy gap of decarboxylation. It is the first calculation evidence supporting decarboxylation as RDS in the NAM mechanism
机译：通过质子转移途径（NAM-H）的正常胺机制被广泛接受与非离子引发剂的多肽合成。除了质子转移之外，在实验中的N-TMS胺引发的活性/控制聚合中发现了三甲基含量1（TMS）群转移方法，但是从未提出相应的机制。在这项工作中，我们采用密度函数理论（DFT）与溶剂化模型研究，以研究定义为Nam-TMS的细节，用于α-氨基酸N-羧酸酐的开环聚合。根据所观察到的下部加法能量屏障，Nam-Tms的TMS转移过程比NAM-H机制更加青睐。 Nam-TMS中的速率确定步骤（RDS）是脱羧步骤，即CO 2的释放，而不是Nam-H中的羰基添加，因为脱羧的低能量间隙的低偶极稳定的前体。它是第一个计算脱羧作为NAM机制RDS的计算证据

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