Polymer Mechanochemistry Enhanced with Mechanically Interlocked Molecules

机械力是一种强大的能量来源，它能够扭曲、弯曲和拉伸化学键，其激活化学反应的方式是独一无二的。在聚合物机械力化学中，聚合物被用来将机械力传递给机械反应官能团(“机械团”)，然后进行机械力化学转换。尽管机械力在促进原本无法进入的反应途径方面具有特殊的能力，但到目前为止，它仅限于涉及键断裂或重排的转变。这些限制的起源是由于这样一个事实，即致动聚合物必须连接到机械团才能激活它，这使得到目前为止不可能：重复激活剪切性机械团或构建分子。这个问题的一个解决方案是找到一种方法，让聚合物在不共价连接的情况下‘抓住’机械团。联锁分子在分子机器的发展中发挥了重要作用，它们非常适合这项任务，因为它们的亚成分在空间中纠缠在一起，但不是共价连接的。因此，它们可以承受较大幅度的内部位移，例如沿轮烷轴线穿梭的大周期，这使它们成为有吸引力的力执行器。在这个项目中，我们想要展示如何使用轮烷结构来重复激活可剪裁的机械团并构建分子。

Mechanical force is a formidable source of energy that, with its ability to distort, bend and stretch chemical bonds, is unique in the way it activates chemical reactions. In polymer mechanochemistry, polymers are used to transduce mechanical force towards a mechanoresponsive functional group (a "mechanophore") that then undergoes a mechanochemical transformation. Although mechanical force is exceptional in its ability to promote reaction pathways that are otherwise inaccessible, it has so far been limited to transformations involving bond cleavage or rearrangements. The origin of these limitations is due to the fact that the actuating polymers have to be linked to the mechanophore to activate it, which has so far made impossible to: repetitively activate scissile mechanophores or to build molecules. A solution to that problem would be to find a way for the polymer to 'grab' the mechanophore without being covalently attached to it. Interlocked molecules, which have been instrumental in the development of molecular machines, are ideally suited for that task because their subcomponents are entangled in space but not covalently linked. As a result, they can undergo large amplitude internal displacements, such as a macrocycle shuttling along the axle of a rotaxane, which makes them attractive force actuators. In this programme, we want to demonstrate how a rotaxane architecture can be used to repetitively activate scissile mechanophores and to build molecules.