Improved enantioselectivity in thiol-ene photopolymerization of sulphur-containing polymers with circularly polarized luminescence
Improved enantioselectivity in thiol-ene photopolymerization of sulphur-containing polymers with circularly polarized luminescence
复制标题
圆偏振发光的含硫聚合物硫醇-烯光聚合中对映选择性的改善
DOI：
10.1039/d1py00082a
复制
发表时间：
2021
影响因子：
4.6
通讯作者：
Zou Gang
中科院分区：
文献类型：
--
作者：
He Chen-Lu;Feng Zeyu;Li Yan;Zhou Manman;Zhao Liyang;Shan Sizhen;Wang Mengqiao;Chen Xin;Wang Xi-Sheng;Zou Gang
圆偏振光（CPL）引发的对映选择性硫醇-烯反应将联合收割机绝对不对称合成与点击反应相结合，使得能够直接从外消旋单体容易地合成光学活性聚（硫醚）。然而，对映选择性低，并且迄今为止尚未满足生产具有明显圆偏振发光的高度不对称聚（硫醚）的挑战。在这里，我们表明，差的对映选择性可以在很大程度上归因于不可避免的外消旋的硫基自由基在生长周期中，更重要的是，它可以通过添加非手性氢原子供体（HAD）补救。在不引入手性诱导剂的情况下，通过改变反应动力学，可以实验控制CPL引发的硫醇-烯反应对映体选择性的增强，最终聚合物链中的对映体单元最大过量（约20%），由此形成光学活性聚（硫醚）不仅表现出团簇化触发发光（CTE），而且首次表现出迷人的圆偏振发光。
Circularly polarized light (CPL)-triggered enantioselective thiol–ene reactions, which combine absolute asymmetric synthesis with click reactions, enable facile synthesis of optically active poly(thioether) directly from a racemic monomer. However, the enantioselectivity is low and the challenge of producing highly asymmetrical poly(thioether) with distinct circularly polarized luminescence has not been met to date. Herein, we show that the poor enantioselectivity can be largely attributed to the inevitable racemization of thiyl radicals during the growth cycle, and more importantly, it can be remedied by addition of achiral hydrogen atom donors (HAD). The enhancement in enantioselectivity of CPL-triggered thiol–ene reactions can be experimentally controlled by varying the reaction kinetics without introducing any chiral inducer other than CPL. A maximum excess of enantiomeric units (∼20%) in the final polymer chains could be obtained, and so-formed optically active poly(thioether) exhibited not only clusterization-triggered emission (CTE), but also fascinating circularly polarized luminescence for the first time.