Controlling the relative motion of the components in mechanical interlocking molecules (MIMs) is important for the development of molecular nanotechnology. Chemists have taken advantage of this opportunity in the design of synthesis of artificial molecular machines (AMMs) which are able to fulfill unidirectional relative motion using ratchet mechanisms. Here we report the design, synthesis and operation of an artificial molecular pump (AMP), which contains a redox switchable pumping cassette connected to a photoswitchable stopper, allowing the application of chemical fuels, electricity and light. Using an energy ratchet mechanism, an intermediate [2]rotaxane has been formed after pumping a ring onto a collecting chain, following a redox cycle. Subsequently, blue light triggers the <i>trans</i>-isomerization of a photoswitchable azobenzene stopper, resulting in the release of the ring back into the bulk solution. The stopper on the AMP is recovered as a result of <i>cis</i>-isomerization with green light irradiation, so that the pump can work again in the next pumping cyclle. This pump design provides for precise and renewable control of the unidirectional relative motions of component parts in AMMs, which may find applications in the integration of cargo-release platforms working in concert.

Sustainable artificial molecular pump working for unidirectional transport

ACS Spring 2022

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