Poly(N-vinylcarbazole) (PNVC-H) is a valuable nonconjugated photoconductive polymer, but the free radical polymerization conditions typically used for its synthesis do not control polymer stereochemistry and are not tolerant to many substituted N-vinylcarbazoles. Here, we report the stereoselective cationic polymerization of a series of 3,6-disubtituted N-vinylcarbazole derivatives using a chiral scandium-bis(oxazoline) Lewis acid catalyst. The combination of asymmetric ion-pairing catalysis and inherent monomer stereoelectronics facilitated stereoselective polymerization at room temperature, which enabled the polymerization of less soluble 3,6-disubstituted-N-vinylcarbazole derivatives. Isotactic halogen-substituted PNVCs demonstrated self-assembly in solution through halogen–halogen bonding, which was not observed in their atactic counterparts. Initial spectral characterization displayed a wide range of excitation–emission profiles for substituted PNVCs, which demonstrate the promise of these materials as a new class of nonconjugated photoconductive polymers for optoelectronic applications. Overall, these results showcase a diverse class of isotactic poly(N-vinylcarbazoles), highlight the benefits of identifying alternative stereocontrol mechanisms for polymerization, and expand the suite of accessible nonconjugated hole-transport materials.

中文翻译：

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3,6-二取代N-乙烯基咔唑的立体选择性聚合


聚（N-乙烯基咔唑）（PNVC-H）是一种有价值的非共轭光电导聚合物，但通常用于其合成的自由基聚合条件不能控制聚合物的立体化学，并且不能耐受许多取代的N-乙烯基咔唑。在这里，我们报道了使用手性钪-双(恶唑啉)路易斯酸催化剂对一系列3,6-二取代的N-乙烯基咔唑衍生物进行立体选择性阳离子聚合。不对称离子对催化和固有单体立体电子学的结合促进了室温下的立体选择性聚合，从而实现了溶解度较低的3,6-二取代-N-乙烯基咔唑衍生物的聚合。全同立构卤素取代的 PNVC 在溶液中通过卤素-卤素键合表现出自组装作用，而在无规立构对应物中未观察到这一点。初始光谱表征显示了取代 PNVC 的各种激发-发射曲线，这证明了这些材料作为用于光电应用的新型非共轭光电导聚合物的前景。总体而言，这些结果展示了多种类型的全同立构聚（N-乙烯基咔唑），突出了确定聚合的替代立体控制机制的好处，并扩展了可利用的非共轭空穴传输材料的套件。