Chemical reactivity underlies our fundamental understanding of many physical and biological phenomena. Chemical reactions are typically initiated by heat, electric current or light. Albeit far less studied, mechanical force is yet another way to orthogonally catalyse chemical reactions. An applied force can substantially reduce the reaction energy barrier, thus enabling reaction pathways that are too slow (or even forbidden) according to the laws of thermodynamics. Single-molecule nanomechanical techniques, including optical and magnetic tweezers and atomic force microscopy, offer the possibility to apply a directional force on an individual chemical bond. In non-covalent (or soft) mechanochemistry, low, sub-nN forces trigger bond rotation or hydrogen-bond rupture. By contrast, in covalent mechanochemistry, higher forces typically result in the breaking and re-forming of individual bonds. This Review focuses on the advances in our mechanistic understanding of single-bond mechanochemistry resulting from single-molecule measurements, as well as on the exciting new perspectives that we envision for this burgeoning field in the near future.

化学反应性是我们对许多物理和生物学现象的基本理解的基础。化学反应通常由热，电流或光引发。尽管研究较少，但是机械力还是正交催化化学反应的另一种方法。施加的力可以大大减少反应能垒，从而根据热力学定律使反应路径过慢（甚至禁止）。单分子纳米机械技术，包括光镊和磁镊以及原子力显微镜，提供了在单个化学键上施加方向力的可能性。在非共价（或软性）机械化学中，亚nN以下的低力会触发键旋转或氢键断裂。相比之下，在共价机械化学中，较高的力通常会导致单个键的断裂和重新形成。这篇综述着重于我们对由单分子测量产生的单键机械化学的机械理解的进展，以及我们在不久的将来为这个新兴领域所构想的令人兴奋的新观点。