Pumping between phases with a pulsed-fuel molecular ratchet.

Area of Science:

• Supramolecular chemistry
• Materials science
• Nanotechnology

Background:

• Sorption processes are crucial for waste sequestration, resource recovery, and catalysis.
• Molecular machines can manipulate systems away from equilibrium using kinetic gating.
• Conventional host-guest chemistry relies on equilibrium-driven binding.

Purpose of the Study:

• To engineer immobilized molecular pumps capable of directional substrate transport.
• To utilize an energy ratchet mechanism for non-equilibrium sorption.
• To demonstrate controlled uptake, storage, and release of molecules using chemical fuels.

Main Methods:

• Immobilizing artificial molecular pumps on polymer beads.
• Utilizing trichloroacetic acid as a chemical fuel to drive sorption.
• Employing fluorescently tagged crown ethers as model substrates.
• Implementing a sequential fuel addition strategy for enhanced uptake.

Main Results:

• Polystyrene beads functionalized with molecular pumps captured fluorescently tagged crown ethers from solution.
• Captured molecules were mechanically trapped in a high-energy, non-equilibrium state after fuel depletion.
• The system demonstrated resistance to removal by dilution or washing, unlike dissipative materials.
• Sequential fuel addition led to further sequestration and increased system non-equilibrium.
• Controlled release of captured molecules was achieved.

Conclusions:

• Immobilized artificial molecular machines can transduce chemical fuel energy for non-equilibrium sorption.
• This approach enables the use, storage, and release of molecules and information.
• The developed system offers a novel platform for advanced materials and separation technologies.