对映体药物
对映选择合成
手性(物理)
共聚物
高分子化学
环氧化物
材料科学
聚酯纤维
战术性
催化作用
聚合物
有机化学
化学
聚合
手征对称破缺
量子力学
物理
Nambu–Jona Lasinio模型
夸克
作者
Jie Li,Bai‐Hao Ren,Shi‐Yu Chen,Guang‐Hui He,Ye Liu,Wei‐Min Ren,Hui Zhou,Xiao‐Bing Lu
标识
DOI:10.1021/acscatal.9b00113
摘要
The asymmetric alternating copolymerization of meso-epoxides with cyclic anhydrides promoted by chiral catalysts or reagents is a powerful strategy for the synthesis of optically active polyesters with main-chain chirality. Herein, we show that, in conjunction with a nucleophilic cocatalyst, enantiopure dinuclear Al(III) complexes efficiently catalyze this asymmetric copolymerization, exhibiting high activity and achieving enantioselectivities up to 99% ee under mild conditions. Copolymer enantioselectivity and catalytic activity are revealed to be strongly affected by the axial linker, chiral diamine structure, and phenolate ortho-substituents. Density functional theory calculations confirm that the reactions corresponding to ring opening at (R)-C–O and (S)-C–O bonds of the Al-coordinated meso-epoxide during copolymerization exhibit significantly different Gibbs free energies of activation (Δ‡G). Enantiopure dinuclear Al(III) complex 3 bearing a hydrogenated binaphthol linker with the matched configuration is demonstrated to be the most active and enantioselective catalyst, featuring a broad substrate scope and allowing one to obtain a wide range of isotactic polyesters with a completely alternating structure and low polydispersity. Notably, most of the produced isotactic polyesters are typical semicrystalline materials with melting temperatures between 120 and 240 °C. Additionally, the mixing of selected isotactic (R)- and (S)-polyesters in a 1:1 mass ratio afforded two crystalline stereocomplexes that exhibited enhanced thermal stability as well as new crystallization behavior and therefore significantly differed from the parent enantiopure polymers.
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