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.

中文翻译：

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用于乙烯聚合和共聚的光响应钯和镍催化剂

在这个贡献中，我们在烯烃聚合催化剂中安装了偶氮苯官能团，并使用光通过光诱导的反式-顺式来调节它们的性能偶氮苯部分的异构化。最初的目标偶氮苯官能化 α-二亚胺钯和镍催化剂不具有光响应性。为了解决这个问题，制备并研究了一种与金属中心具有间断共轭的亚胺-胺体系，以及一种在远离金属中心的共价位置处带有偶氮苯单元的夹心型α-二亚胺体系。我们证明了光可用于调节它们在乙烯聚合和与极性共聚单体共聚中的性能，从而实现对聚合过程、聚合物微观结构和聚合物性能的光诱导控制。更有趣的是，光介导的性质变化归因于一个系统中的配体电子效应和另一个系统中的配体空间效应。