Solvent-Directed Helical Stereomutation Discloses Pathway Complexity on N-Heterotriangulene-Based Organogelators

Abstract

The chiroptical features of supramolecular polymers formed from N-heterotriangulenes 1-3 have been investigated by circular dichroism (ECD) and vibrational circular dichroism (VCD) techniques. In solution, the CD spectra demonstrate that the helicity of the aggregates depends on only the stereogenic centres located at the peripheral chains. In the gel state, the chiroptical features are conditioned by the point chirality of the stereogenic centres and by the achiral solvent utilised. Sonication of the gels formed in CCl₄ reveals both kinetic and thermodynamic phases. These findings reveal the presence of pathway complexity in the gel state triggered by sonication. The described solvent-induced helical stereomutation demonstrates that the gel state can be utilised as an outstanding benchmark for investigating uncommon chiroptical effects and to explore the rules of chirality transmission.

Keywords: chirality; gels; helical structures; self-assembly; supramolecular polymers.