Chemically fuelled autonomous directional linear motion at the molecular level

自主的、以化学为燃料的定向运动支持了自然界许多壮观的生物马达蛋白的功能。在小分子系统中模仿或复制这种行为是一个非常令人兴奋的挑战。轮烷，包括一个围绕着分子线的大环，已经被广泛地用于研究一个分子组分相对于另一个分子组分的定向线性运动。除了一些值得注意的例外，这些系统中的运动通常是通过“智能输入”来控制的，即实验者通过添加酸或金属离子等添加剂，将大环的相对结合亲和力改变为分子线上的特定位置。相反，在这项研究计划中，我们将设计和开发一个以轮烷为基础的自主运行的系统。大环与一种过渡金属有关，并以顺序的方式催化沿分子线引入动力学障碍(官能化)，抑制“向后”方向的运动。定向运动是自主进行的：只要大循环催化剂随着每一次功能化而翻转，系统除了持续供应化学燃料外，不需要任何外部输入。

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.