Molecular-Pump-Enabled Synthesis of a Daisy Chain Polymer

Area of Science:

• Supramolecular Chemistry
• Polymer Science
• Nanotechnology

Background:

• The development of advanced polymers with controlled architectures is crucial for materials science.
• Mechanically interlocked polymers offer unique properties but their synthesis remains challenging.
• Molecular machines provide novel tools for constructing complex molecular architectures.

Purpose of the Study:

• To demonstrate the assembly of a kinetically trapped daisy chain polymer using redox control.
• To utilize a self-complementary monomer incorporating a molecular pump and a cyclobis(paraquat-p-phenylene) ring.
• To explore the energy ratchet mechanism for polymer formation and manipulation.

Main Methods:

• Design and synthesis of a self-complementary monomer with a molecular pump and a cyclobis(paraquat-p-phenylene) ring.
• Employing redox stimuli (reduction and oxidation) to control polymer assembly and disassembly.
• Utilizing radical-pairing interactions for supramolecular polymer formation.
• Leveraging the energy ratchet mechanism for kinetic trapping of the polymer.

Main Results:

• Successful self-assembly of a supramolecular daisy chain polymer via radical-pairing interactions upon monomer reduction.
• Formation of an out-of-equilibrium, kinetically trapped daisy chain polymer by oxidizing radical cations to dications, forcing ring threading.
• Demonstration of reversible switching between the supramolecular polymer and the monomer through controlled redox cycles.
• Achieved depolymerization via slow oxidation, regenerating the initial monomer.

Conclusions:

• A novel method for constructing kinetically trapped daisy chain polymers under redox control has been established.
• The energy ratchet mechanism effectively drives the formation and kinetic trapping of mechanically interlocked polymer structures.
• This proof-of-concept study paves the way for advanced synthesis of mechanically interlocked polymers using molecular machines.