The formation of helical assemblies from achiral supramacromolecules has been a highly mysterious process, but is of interest for the generation of a variety of structures and properties. Herein, novel hierarchical superhelices are developed from self-assembly of achiral dendron-jacketed block copolymers (DJBCPs). The presence of focal asymmetry in both the stereochemistry of the dendrons (donors) and interactive binding sites of the copolymer chains (acceptors) plays a pivotal role in generating a spontaneous symmetry breaking through tailored donor–acceptor matching via hydrogen bonding. The focal asymmetry, on a scale of several nanometers, propagates to helical twists of the achiral DJBCP hierarchical assemblies over hundreds of nanometers, such that the primary molecular asymmetry sequentially triggers a secondary helical conformation of the dendron-jacketed blocks, then tertiary supramolecular helical assemblies and eventually quaternary superhelices. The helical twisting power of the superhelices is tunable using the dendron grafting ratio, indicating that the magnitude of helical twisting can be quantitatively adjusted from local to entire structures.

中文翻译：

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由非分子树枝状夹套嵌段共聚物的超分子对焦点不对称引起的具有可调扭曲力的超螺旋

由非手性超分子形成螺旋组装体一直是一个高度神秘的过程，但是对于产生各种结构和性质却是令人感兴趣的。在本文中，从非手性树突夹套嵌段共聚物（DJBCP）的自组装发展出新型的分层超螺旋。焦不对称的树突（供体）和所述共聚物链（受主）的交互结合位点的两个立体化学存在在产生自发对称性通过针对供体-受体匹配打破了关键作用通过氢键。焦点不对称在几纳米的尺度上传播到数百纳米上的非手性DJBCP分层组件的螺旋形扭曲，因此主要分子不对称性依次触发树突夹套的嵌段的次级螺旋构象，然后是三级超分子螺旋组件最终四元超螺旋。使用树突接枝率可以调节超螺旋的螺旋扭曲力，这表明可以从局部结构到整个结构定量地调整螺旋扭曲的大小。