Thermally Activated Stereoinversion in Benzotrithiophene-Based Supramolecular Polymers withWater as the Effector

Abstract

We report the synthesis of the chiral benzotrithiophene (BTT) derivative 1, which self-assembles into helicalsupramolecular polymers. The C3 symmetry of BTT 1 enables a unique temperature-dependent stereomutation process inwhich water acts as a key effector. Circular dichroism measurements reveal that a higher water content induces a doublestereomutation, ultimately restoring the original helicity. In contrast, reducing the water content leads to a single, stablestereomutation, which duration depends on the amount of water in solution. To elucidate the stereomutation mechanism,we conducted a multi-level computational study, identifying two main conformations for the monomeric species that leadto diastereomeric helices with different preferred handedness, thus resulting in opposite dichroic patterns. The transitionbetween these aggregates involves rotation of the BTT cores and amide groups, a process significantly facilitated by watermolecules via triple hydrogen bonding within the helical stack. These findings exhibit the crucial role of the solvent inmodulating chiral supramolecular polymer structures and provide unprecedented insights into the influence of water onself-assembly and stereomutation processes