Chemically fuelled autonomous directional linear motion at the molecular level

自主的、化学燃料驱动的定向运动支撑着许多大自然伟大的生物运动蛋白的功能。在小分子系统中模仿或复制这种行为是一项非常令人兴奋的挑战。轮烷是由环绕分子线的大环组成的，已被广泛用于研究一种分子组分相对于另一种分子组分的定向线性运动。除了一些明显的例外，这些系统中的运动通常是通过“智能输入”来控制的，其中实验者通过添加诸如酸或金属离子之类的添加剂来改变大环对分子线上特定位点的相对结合亲和力。相反，在这个研究项目中，我们将设计和开发一个基于轮烷的自主运行系统。大环与过渡金属相关，并催化沿分子线引入动力学屏障（功能化），以顺序的方式，抑制“向后”方向的运动。定向运动是自主发生的：只要大循环催化剂随每次功能化而翻转，除了化学燃料的持续供应外，该系统不需要外部输入。

Autonomous, chemically fuelled directional motion underpins the function of many of nature's magnificent biological motor proteins. Mimicking or replicating such behaviour in small molecule systems is a hugely exciting challenge. Rotaxanes, comprising a macrocycle encircling a molecular thread, have been used extensively to study the directional linear motion of one molecular component with respect to another. With some notable exceptions, motion in these systems is generally controlled through "intelligent input", where the experimentalist changes the relative binding affinities of the macrocycle towards specific sites on the molecular thread through the addition of additives such as acid or metal ions. Conversely, in this research programme, we will design and develop a rotaxane-based system which operates autonomously. The macrocycle is associated with a transition metal and catalyses the introduction of kinetic barriers (functionalisations) along the molecular thread, in a sequential fashion, inhibiting movement in the "backwards" direction. The directional motion occurs autonomously: provided the macrocycle catalyst turns over with each functionalisation, the system requires no external input other than a constant supply of chemical fuel.