Main-chain linear polyrotaxanes: synthesis, characterization, and conformational modulation.
Main-chain linear polyrotaxanes: synthesis, characterization, and conformational modulation.
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DOI：
10.1002/chem.201203165
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发表时间：
2013-01
期刊：
影响因子：
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通讯作者：
Jimin Han;Yonghong Zhang;Xiao-Ye Wang;Chenjiang Liu;Jie‐Yu Wang;J. Pei
中科院分区：
文献类型：
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作者：
Jimin Han;Yonghong Zhang;Xiao-Ye Wang;Chenjiang Liu;Jie‐Yu Wang;J. Pei
通过强冠醚/氨基(DB24C8/DBA)主客体相互作用和点击化学，合成了两个功能主链线性聚轮烷，一个是贯穿多个大环的共价聚合物链(P1)，另一个是由多个重复轮烷单元组成的聚[n]轮烷链(P2)。两个多轮烷中的轮轴单元之间的能量转移被用来洞察其生成的多轮烷的构象信息。通过稳态光谱和时间分辨光谱研究了聚合物P1和P2在溶液中的构象差异。动态/静态光散射和原子力显微镜的进一步研究表明，聚合物P1是不弯曲的，具有刚性的棒状结构，而聚合物P2是弯曲的和柔性的。这种灵活的拓扑结构有助于聚合物P2自组装成相对较大的球状颗粒。此外，车轮和车桥单元之间的能量传递通过添加特定的阴离子或碱来控制。阴离子诱导的能量增强归因于聚合物链之间静电相互作用的改变。碱基驱动的分子穿梭打破了DB24C8/DBA的主客体相互作用。这些结果证实了分子内和分子间的静电相互作用对于调控构象拓扑是至关重要的，构象拓扑决定了聚轮烷在溶液中的组装。
Two functional main-chain linear polyrotaxanes, one a covalent polymeric chain that threads through many macrocycles (P1) and the other a poly[n]rotaxane chain that is composed of many repeating rotaxane units (P2), were synthesized by employing strong crown-ether/ammonium-based (DB24C8/DBA) host-guest interactions and click chemistry. Energy transfer between the wheel and axle units in both polyrotaxanes was used to provide insight into the conformational information of their resulting polyrotaxanes. Steady-state and time-resolved spectroscopy were performed to understand the conformation differences between polymers P1 and P2 in solution. Additional investigations by using dynamic/static light scattering and atomic force microscopy illustrated that polymer P1 was unbending and had a rigid rod-like structure, whilst polymer P2 was curved and flexible. This flexible topology facilitated the self-assembly of polymer P2 into relatively large ball-shaped particles. In addition, the energy transfer between the wheel and axle units was controlled by the addition of specific anions or base. The anion-induced energy enhancement was attributed to a change in electrostatic interactions between the polymer chains. The base-driven molecular shuttle broke the DB24C8/DBA host-guest interactions. These results confirm that both intra- and intermolecular electrostatic interactions are crucial for modulating conformational topology, which determines the assembly of polyrotaxanes in solution.