Artificial molecular pumps

Reflecting on recent progress in bottom-up engineering focused on creating the smallest devices capable of controlling nanoscale motion, artificial molecular pumps (AMPs) are among some of the most highly studied wholly synthetic machines. In addition to exploring their applications in synthesizing mechanically bonded compounds, including polymers and materials, the design features and underlying fundamental physical principles of rotaxane-based AMPs are discussed in this Primer. Current limitations in AMP design are reviewed, and potential strategies to overcome these limitations are evaluated. Anticipated future developments in this rapidly evolving area of science are considered. Although still in their infancy, the design and synthesis of AMPs have already led to new insights into fundamental molecular principles, such as kinetic asymmetry, trajectory thermodynamics and the non-equilibrium pumping equality. With the ineluctable continuing development of AMPs, an increasing number of ground-breaking discoveries are anticipated in the physical and life sciences.