Molecular devices based on the mechanical bond: recent advances

The bottom-up construction and operation of nanoscale devices – namely, multicomponent (supra)molecular architectures capable of performing functions beyond the reach of their individual components – constitute a central focus in nanoscience and a compelling challenge in nanotechnology. Over the past three decades, the development of artificial molecular devices, including molecular machines and motors, has continuously stimulated the creativity of chemists, and the field continues to evolve at a remarkable pace. Among the strategies employed, the mechanical bond has emerged as a particularly powerful means of connecting molecular components to build functional systems. Mechanically interlocked molecules uniquely combine the robustness of covalent frameworks with the dynamic properties of non-covalent assemblies. Moreover, the precise modulation of steric and electronic interactions between mechanically bonded components offers rich opportunities for the emergence of novel functions. Recent advances in the design and synthesis of rotaxanes, catenanes and related interlocked structures have enabled the construction and operation of increasingly complex molecular devices and materials, many of which are capable of executing well-defined tasks. In this review, we present selected examples – classified according to their functional outputs – that exemplify the progress and potential of this rapidly developing area over the past decade.