Wang Jianqun, Zhu Yinuo, Li Maosheng, Wang Yanchao, Wang Xianhong, Tao Youhua
Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Renmin Street 5625, Changchun, 130022, P. R. China.
University of Science and Technology of China, Hefei, 230026, P. R. China.
Angew Chem Int Ed Engl. 2022 Sep 5;61(36):e202208525. doi: 10.1002/anie.202208525. Epub 2022 Jul 28.
Ring-opening copolymerizations have emerged as a powerful approach towards the creation of sustainable polymers. Typical H-bonding catalysts for ring-opening are subject to a single catalytic site. Here we describe a H-bond-donor/Lewis-acidic-boron organocatalyst featuring two distinct catalytic sites in one molecule. The ring-opening copolymerization of epoxides with anhydride mediated by these modular, and tunable catalysts achieves high selectivity (>99 % polyester selectivity) and markedly higher activity compared to either of the di-thiourea analogues or any combinations of them. Calculations and experimental studies reveal that the superior catalytic performance arises from tug-of-war between two differentiated catalytic sites: thiourea pulls off the propagating chain-end from boron center, simultaneously enhancing the role of monomer activation and also nucleophilicity of the propagation intermediates.
开环共聚已成为一种制备可持续聚合物的有力方法。典型的用于开环的氢键催化剂只有一个催化位点。在此，我们描述了一种在一个分子中具有两个不同催化位点的氢键供体/路易斯酸性硼有机催化剂。由这些模块化且可调谐的催化剂介导的环氧化物与酸酐的开环共聚实现了高选择性（>99%聚酯选择性），并且与二硫脲类似物中的任何一种或它们的任何组合相比，活性明显更高。计算和实验研究表明，优异的催化性能源于两个不同催化位点之间的拔河效应：硫脲将增长链端从硼中心拉离，同时增强了单体活化的作用以及增长中间体的亲核性。
