Self-Sorting of Rosette-Forming Naphthalene Barbiturates into Distinct Toroidal Assemblies

Area of Science:

• Supramolecular chemistry
• Polymer science
• Materials science

Background:

• Supramolecular polymers self-assemble from smaller units into larger structures.
• Controlling the size and morphology of self-assembled polymers is crucial for materials design.
• Naphthalene-based monomers offer unique structural properties for self-assembly.

Purpose of the Study:

• To design and investigate a narcissistic self-sorting system for supramolecular polymers.
• To control the formation of toroidal and helicoidally elongated supramolecular polymers.
• To understand the self-sorting mechanism and influence of monomer ratios on polymerization.

Main Methods:

• Synthesis of mono- and bisnaphthalene-based supramolecular monomers.
• Controlled cooling of pure monomers and a 1:1 mixture in a nonpolar solvent.
• Characterization of supramolecular polymer morphology and size using spectroscopy and microscopy (implied).
• Absorption spectroscopy to study nucleation and polymerization dynamics.

Main Results:

• Pure mono- and bisnaphthalene monomers formed toroidal and helicoidally elongated supramolecular polymers, respectively.
• A 1:1 mixture of monomers yielded self-sorted smaller (15 nm) and larger (26 nm) toroidal polymers.
• Mononaphthalene monomers inhibited bisnaphthalene monomer nucleation, reducing polymerization cooperativity.

Conclusions:

• A novel narcissistic self-sorting system was successfully demonstrated using naphthalene-based supramolecular monomers.
• The system allows for the controlled formation of distinct supramolecular polymer sizes through self-sorting.
• Monomer interactions, specifically nucleation inhibition, play a key role in the observed self-sorting and polymerization behavior.