Peng Dan, Chen Changle
Hefei National Laboratory for Physical Sciences at the Microscale, CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, China.
Angew Chem Int Ed Engl. 2021 Oct 4;60(41):22195-22200. doi: 10.1002/anie.202107883. Epub 2021 Sep 2.
In this contribution, we install an azobenzene functionality in olefin polymerization catalysts and use light to modulate their properties via photoinduced trans-cis isomerization of the azobenzene moiety. The initially targeted azobenzene-functionalized α-diimine palladium and nickel catalysts are not photoresponsive. To address this issue, an imine-amine system bearing interrupted conjugation with the metal center, and a sandwich-type α-diimine system bearing an azobenzene unit at a position covalently far from the metal center were prepared and studied. We demonstrate that light can be used to tune their properties in ethylene polymerization and copolymerization with polar comonomers, enabling light-induced control of the polymerization processes, polymer microstructures and polymer properties. More interestingly, the light-mediated property changes were attributed to ligand electronic effects in one system and ligand steric effects in the other.
在本论文中，我们在烯烃聚合催化剂中引入了偶氮苯官能团，并通过偶氮苯部分的光致反式-顺式异构化，利用光来调节其性能。最初目标的偶氮苯官能化α-二亚胺钯和镍催化剂没有光响应性。为了解决这个问题，我们制备并研究了一种与金属中心共轭中断的亚胺-胺体系，以及一种在与金属中心共价距离较远的位置带有偶氮苯单元的三明治型α-二亚胺体系。我们证明，光可用于调节它们在乙烯聚合以及与极性共聚单体的共聚反应中的性能，从而实现光诱导的聚合过程、聚合物微观结构和聚合物性能的控制。更有趣的是，光介导的性能变化在一个体系中归因于配体电子效应，而在另一个体系中归因于配体空间效应。
