Supramolecular Pseudorotaxane Polymers from Biscryptands and Bisparaquats

Area of Science:

• Supramolecular Chemistry
• Polymer Science
• Materials Chemistry

Background:

• Cryptands are macrocyclic compounds known for their ability to bind ions.
• Supramolecular polymers are formed through non-covalent interactions.
• Previous research has explored pseudorotaxanes for self-assembly.

Purpose of the Study:

• To synthesize new bis(dibenzo-30-crown-10-based cryptand)s.
• To investigate the self-assembly of these cryptands with bisparaquats into polymeric structures.
• To characterize the resulting supramolecular polymers and their physical properties.

Main Methods:

• Synthesis of five new bis(dibenzo-30-crown-10-based cryptand)s.
• Cooperative complexation studies using dibenzyl paraquat TFSI.
• Self-assembly experiments with bisparaquats and characterization of resulting polymers (viscosity measurements, molecular weight determination).

Main Results:

• Two cryptands with long, flexible spacers exhibited cooperative complexation.
• Self-assembly with bisparaquats yielded high molecular weight supramolecular pseudorotaxane polymers in solution.
• Continuous, flexible fibers were formed from concentrated polymer solutions; high molecular weight (M_n = 407 kDa) was confirmed.

Conclusions:

• The study reports the first truly polymeric pseudorotaxane-type AA/BB supramolecular polymers.
• Flexible spacers are crucial for achieving high molecular weights and fiber formation.
• These findings open new avenues for designing advanced functional materials through supramolecular polymerization.