Directional Macrocycle Transport, Release, and Recapture Enabled by a Rotaxane Transporter

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Chemical Engineering

Background:

• Molecular machines require precise control over component movement and function.
• Rotaxanes offer a unique platform for constructing mechanically interlocked molecules with tunable properties.

Purpose of the Study:

• To construct and demonstrate a rotaxane-based transporter for directional macrocycle transport, release, and recapture.
• To investigate the iterative operation of such a molecular transporter.

Main Methods:

• Synthesis of a rotaxane featuring a dibenzo-24-crown-8 macrocycle and specific stations (dibenzylammonium/methyl triazolium) and stoppers (anthracene/triisopropylsilyl-acetylene).
• Utilized chemical inputs (base, fluoride) to induce directional shuttling, release, and reassembly of the rotaxane.
• Employed CuAAC click chemistry to reestablish the mechanical bond for iterative cycling.

Main Results:

• Achieved directional shuttling of the macrocycle between stations in response to chemical stimuli.
• Demonstrated the release of the macrocycle and half-thread upon stopper cleavage by fluoride.
• Successfully recaptured the macrocycle and reassembled the rotaxane transporter for iterative operation.

Conclusions:

• The developed rotaxane transporter enables controlled, directional macrocycle transport, release, and recapture.
• The system exhibits iterative functionality, paving the way for reusable molecular machines.
• This molecular design offers a promising approach for advanced supramolecular systems and nanodevices.