Influence of the Norbornene Anchor Group in Ru-Mediated Ring-Opening Metathesis Polymerization: Synthesis of Linear Polymers
Influence of the Norbornene Anchor Group in Ru-Mediated Ring-Opening Metathesis Polymerization: Synthesis of Linear Polymers
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降冰片烯锚定基团对钌介导的开环复分解聚合反应的影响：线性聚合物的合成
DOI：
10.1021/acs.macromol.3c00172
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发表时间：
2023
期刊：
影响因子：
5.5
通讯作者：
Matson, John B.
中科院分区：
文献类型：
--
作者：
Scannelli, Samantha J.;Paripati, Anshul;Weaver, Jeffrey R.;Vu, Clark;Alaboalirat, Mohammed;Troya, Diego;Matson, John B.
由Grubbs的第一代催化剂[G1，（PCy 3）2（Cl）2 RuCHPh]和Grubbs的第三代催化剂[G3，（H2 IMes）（Cl）2（pyr）2 RuCHPh]介导的开环易位聚合（ROMP）可以对一些单体类别（最常见的取代的双烯烃）表现出活性特征。在这里，我们研究了各种锚基团，一系列的原子连接的可聚合的环己烯单元的功能基团，影响在一系列的小分子exo-环己烯单体的开环易位聚合中的活性。我们首先用密度泛函理论方法设计并计算了61个单体的HOMO能，发现这些能量跨越25 kcal/mol的范围。然后，我们进行了动力学实验，使用1H NMR光谱测量的传播速率常数（kp，obs）在相同的条件下为八个选定的单体与不同的锚基团的HOMO能量的范围内。我们观察到的HOMO能量或HOMO/LUMO能隙和measuredkp之间的正相关性，obsvalues两种催化剂，揭示了一个30倍和10倍的变化inkp，obsvalues在整个系列的G1和G3，分别。有趣的是，我们观察到具有G3催化剂的最高HOMO能量的三种单体的平台，这表明在一定水平以上，HOMO能量不再影响在这里研究的条件下的速率决定步骤。螯合研究表明，八个单体中只有一个单体显示出可测量的单体上的富电子基团与催化剂的结合，但对kp没有明显的影响。最后，我们利用1H NMR光谱测量催化剂分解的速率在每个单体的存在下，在开环易位聚合的一个关键终止途径。最终，我们确定锚基团基本上不影响催化剂分解，这是终止速率常数（kt）的代表。总之，这些结合的计算和实验研究共同证明，在使用G1和G3催化剂的外-异戊二烯单体的ROMP中，如通过相对kp/ktratios测量的活性主要由与HOMO能量相关的锚基团的kp控制。
Ring-opening metathesis polymerization (ROMP) mediated by Grubbs’ first-generation catalyst [G1, (PCy3)2(Cl)2RuCHPh] and Grubbs’ third-generation catalyst [G3, (H2IMes)(Cl)2(pyr)2RuCHPh] can exhibit living characteristics for some monomer classes, most commonly substituted norbornenes. Here, we studied how various anchor groups, the series of atoms connecting the polymerizable norbornene unit to a functional group, affect livingness in ROMP in a series of small-moleculeexo-norbornene monomers. We first designed and calculated the HOMO energy of 61 monomers using density functional theory methods, finding that these energies spanned a range of 25 kcal/mol. We then performed kinetics experiments using1H NMR spectroscopy to measure the propagation rate constant (kp,obs) under identical conditions for eight selected monomers with different anchor groups across the range of HOMO energies. We observed a positive correlation between the HOMO energy or the HOMO/LUMO energy gap and measuredkp,obsvalues for both catalysts, revealing a 30-fold and a 10-fold variation inkp,obsvalues across the series for G1 and G3, respectively. Interestingly, we observed a plateau for the three monomers with the highest HOMO energies for G3 catalyst, suggesting that above a certain level, the HOMO energy no longer influenced the rate-determining step under the conditions studied here. Chelation studies revealed that only one of the eight monomers showed measurable binding of electron-rich groups on the monomer to the catalyst, but with no apparent effect onkp. Finally, we utilized1H NMR spectroscopy to measure the rate of catalyst decomposition in the presence of each monomer, a key termination pathway in ROMP. Ultimately, we determined that the anchor group did not substantially affect catalyst decomposition, a proxy for the termination rate constant (kt). In sum, these combined computational and experimental studies collectively demonstrate that livingness in ROMP ofexo-norbornene monomers using G1 and G3 catalysts, as measured by relativekp/ktratios, is primarily controlled by thekpof the anchor group, which is correlated with the HOMO energy.
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影响因子：
5.5
作者：
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通讯作者：
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影响因子：
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作者：
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影响因子：
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作者：
J. M. E. Matos;B. S. Lima
通讯作者：
B. S. Lima
影响因子：
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作者：
W. Wolf;Tzu-Pin Lin;R. Grubbs
通讯作者：
W. Wolf;Tzu-Pin Lin;R. Grubbs
影响因子：
5.5
作者：
Blosch, Sarah E.;Scannelli, Samantha J.;Matson, John B.
通讯作者：
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