Chemical Control of Supramolecular Copolymerization by Modulating the Chirality Transfer of Helical-Chiral...

Controlling supramolecular polymerization is essential to accessing diverse supramolecular structures. Here, we report a distinct strategy to control supramolecular polymerization through helical-sense-matching-promoted chiral transfer from basic to acidic pillar[5]arene (P5A) monomers. Our strategy uses the fact that a basic P5A monomer bearing bulky tertiary amine substituents acts as a chiral inducer because of its static helicity, whereas an acidic P5A monomer with short aliphatic carboxylic acid groups exhibits dynamic helicity with interconversion between P and M conformers. When we mixed basic P5A (static M-helicity) with acidic P5A (dynamic P- and M-helicity), we obtained a kinetically favored metastable amorphous aggregate. This aggregate formed through multiple helical-sense-matched and -mismatched ion-pairing interactions between the basic and acidic P5A monomers. Subsequently, time-dependent supramolecular polymerization gradually occurred, which transformed the amorphous aggregates into thermodynamically stable nanowires. This process was driven by helical-sense matching, which involved the conversion of the helicity of acidic P5A from P to M and then connection between the M-helical basic and acidic P5A monomers. The polymerization can be accelerated by acidic or basic additives and suppressed by the addition of guest molecules. Because of the multiple helical-sense-matched ion-pairing interactions, the resulting supramolecular copolymer exhibited exceptional stability in polar solvents, at high temperatures, and in harsh environments.