Supramolecular polymerization of oligopyrenotides – stereochemical control by single, natural nucleotides

Amphiphilic heptapyrenotides (Py sub(7)) assemble into supramolecular polymers. Here we present a comprehensive spectroscopic study of aggregates and co-aggregates of the non-chiral Py sub(7) and its mono- or di-substituted nucleotide analogs (Py sub(7)-N and N-Py sub(7)-N'). The data show that the formation of supramolecular polymers from oligopyrenotides is highly sensitive to the nature of the attached, chiral auxiliary. A single natural nucleotide may be sufficient for the fine tuning of the aggregates' properties by changing the mechanism of aggregation from an isodesmic to a nucleation-elongation process, which results in a high degree of amplification of chirality in the formed supramolecular polymers. Watson-Crick complementarity does not play a significant role, since co-aggregates of oligomers modified with complementary nucleotides show no signs of supramolecular polymerization. Depending on the nucleotide, the helical sense of the polymers is shifted to an M-helix or a P-helix. The findings demonstrate the value of oligopyrenotides as oligomeric building blocks for the generation of optically active supramolecular polymers.