Tailoring Dynamic Chiral Supramolecular Assembly with Phototriggered Radical Anions of C₃-Symmetric Triphenylene Triimides

This study develops a new type of C3-symmetric triphenylene triimide (TTI) bearing different oligo-(ethylene glycol) side chains via imide linkages. By exploiting the unique TTI molecule as a building block, supramolecular polymerization is explored based on pi-pi stacking and hydrophilic/hydrophobic interactions in various solvents and the rates of heating/cooling process. The molecular chirality of the TTI unimer induces a preferential helicity formation in fibrous structures, while the achiral side chain allows the formation of linear nanofibers. The stacking type of supramolecular polymerization is highly dependent on the point chirality of the side chains, as indicated by the spectroscopic analyses, including ultraviolet-visible (UV/vis) and circular dichroism (CD) spectroscopy with atomic force microscopy (AFM), transmission electron microscopy (TEM), and wide-angle X-ray scattering (WAXS). Interestingly, the supramolecular polymerization does not occur in its monomeric state due to the generation of radical anions from the imide groups upon UV irradiation. In contrast, the fibrous structure in the assembled state is maintained, owing to the intermolecular interaction. This study provides a new direction in the phototriggered control of the supramolecular chiral assembly.