A Molecular Dual Pump.

Area of Science:

• Supramolecular Chemistry
• Nanotechnology
• Chemical Engineering

Background:

• Artificial molecular machines (AMMs) utilize energy ratchets for controlled molecular motion.
• Mechanically interlocked molecules (MIMs) form the basis of AMMs, with motion controlled by altering kinetic barriers and thermodynamic wells.
• Previous work established artificial molecular pumps (AMPs) for sequential ring pumping onto molecular dumbbells.

Purpose of the Study:

• To report a novel molecular dual pump (MDP) composed of two linked AMPs.
• To demonstrate linear, controlled pumping of a single ring on and off a molecular dumbbell using redox properties.
• To showcase the MDP's ability to capture and release molecules via an energy ratchet mechanism.

Main Methods:

• Construction of a head-to-tail linked MDP with two individual AMPs.
• Exploitation of redox properties to control the pumping action.
• Utilizing noncovalent interactions and an energy ratchet mechanism for molecular capture and release.
• 1D and 2D 1H NMR spectroscopy for monitoring unidirectional motion and controlled capture/release.

Main Results:

• The MDP successfully achieved unidirectional, linear pumping of a single ring on and off a molecular dumbbell.
• Controlled capture and subsequent release of the ring into solution were demonstrated.
• The system's function was validated through NMR spectroscopy and control experiments.

Conclusions:

• The developed MDP represents a significant advancement in AMMs, demonstrating precise control over molecular transport.
• This work serves as a precursor to more complex AMMs capable of membrane transport, analogous to biological systems like bacteriorhodopsin.
• The MDP lays the foundation for future molecular transporting platforms with programmable cargo uptake and release functionalities.