Jaynes Tyler J, Sharafi Mona, Campbell Joseph P, Bocanegra Jessica, McKay Kyle T, Little Kassondra, Osadchey Brown Reilly, Gray Danielle L, Woods Toby J, Li Jianing, Schneebeli Severin T
Department of Chemistry, University of Vermont, Burlington, VT, United States.
George L. Clark X-Ray Facility and 3M Materials Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, United States.
Front Chem. 2021 Apr 28;9:620017. doi: 10.3389/fchem.2021.620017. eCollection 2021.
This work presents the first transition metal-free synthesis of oxygen-linked aromatic polymers by integrating iterative exponential polymer growth (IEG) with nucleophilic aromatic substitution (SAr) reactions. Our approach applies methyl sulfones as the leaving groups, which eliminate the need for a transition metal catalyst, while also providing flexibility in functionality and configuration of the building blocks used. As indicated by 1) H-H NOESY NMR spectroscopy, 2) single-crystal X-ray crystallography, and 3) density functional theory (DFT) calculations, the unimolecular polymers obtained are folded by nonclassical hydrogen bonds formed between the oxygens of the electron-rich aromatic rings and the positively polarized C-H bonds of the electron-poor pyrimidine functions. Our results not only introduce a transition metal-free synthetic methodology to access precision polymers but also demonstrate how interactions between relatively small, neutral aromatic units in the polymers can be utilized as new supramolecular interaction pairs to control the folding of precision macromolecules.
本研究通过将迭代指数聚合（IEG）与亲核芳香取代（SAr）反应相结合，首次实现了无过渡金属合成氧连接的芳香聚合物。我们的方法使用甲基砜作为离去基团，无需过渡金属催化剂，同时在所用结构单元的功能和构型方面提供了灵活性。如1）H-H NOESY核磁共振光谱、2）单晶X射线晶体学和3）密度泛函理论（DFT）计算所示，所得单分子聚合物通过富电子芳香环的氧与贫电子嘧啶官能团的正极化C-H键之间形成的非经典氢键折叠。我们的结果不仅引入了一种无过渡金属的合成方法来制备精密聚合物，还展示了聚合物中相对较小的中性芳香单元之间的相互作用如何作为新的超分子相互作用对来控制精密大分子的折叠。
