Folding is a ubiquitous process that nature uses to control the conformations of its molecular machines, allowing them to perform chemical and mechanical tasks. Over the years, chemists have synthesized foldamers that adopt well-defined and stable folded architectures, mimicking the control expressed by natural systems^1,2. Mechanically interlocked molecules, such as rotaxanes and catenanes, are prototypical molecular machines that enable the controlled movement and positioning of their component parts^3,4,5. Recently, combining the exquisite complexity of these two classes of molecules, donor–acceptor oligorotaxane foldamers have been synthesized, in which interactions between the mechanically interlocked component parts dictate the single-molecule assembly into a folded secondary structure^6,7,8. Here we report on the mechanochemical properties of these molecules. We use atomic force microscopy-based single-molecule force spectroscopy to mechanically unfold oligorotaxanes, made of oligomeric dumbbells incorporating 1,5-dioxynaphthalene units encircled by cyclobis(paraquat-p-phenylene) rings. Real-time capture of fluctuations between unfolded and folded states reveals that the molecules exert forces of up to 50 pN against a mechanical load of up to 150 pN, and displays transition times of less than 10 μs. While the folding is at least as fast as that observed in proteins, it is remarkably more robust, thanks to the mechanically interlocked structure. Our results show that synthetic oligorotaxanes have the potential to exceed the performance of natural folding proteins.

折叠是大自然无处不在的过程，自然界可以使用它来控制其分子机器的构象，从而使它们能够执行化学和机械任务。多年来，化学家已经合成了采用明确定义且稳定的折叠式结构的折叠器，模仿了自然系统^1,2所表达的控制。机械互锁的分子，例如轮烷和链烷，是典型的分子机器，能够对其组成部分进行受控的移动和定位^3,4,5。最近，结合这两类分子的复杂性，合成了供体-受体低聚轮烷折叠剂，其中机械互锁的组成部分之间的相互作用决定了单分子组装成折叠的二级结构^6,7,8。在这里，我们报告这些分子的机械化学性质。我们使用基于原子力显微镜的单分子力光谱技术，对低聚轮烷进行机械展开，该低聚轮烷是由低聚哑铃制成，并结合有由环双（百草枯-p）包围的1,5-二氧萘单元。-亚苯基）环。实时捕获未折叠状态和折叠状态之间的波动，揭示了分子对高达150 pN的机械负载施加了高达50 pN的力，并显示了小于10μs的跃迁时间。尽管折叠至少与蛋白质中观察到的折叠速度一样快，但由于机械互锁的结构，折叠效果显着增强。我们的结果表明，合成的低聚轮烷有潜力超过天然折叠蛋白的性能。