Morphological Control of Coil–Rod–Coil Molecules Containing <i>m</i>‑Terphenyl Group: Construction of Helical Fibers and Helical Nanorings in Aqueous Solution
2018-08-14T00:00:00Z (GMT) by
Rod–coil molecules, composed of rigid segments and flexible coil chains, have a strong intrinsic ability to self-assemble into diverse supramolecular nanostructures. Herein, we report the synthesis and the morphological control of a new series of amphiphilic coil–rod–coil molecular isomers <b>1</b>–<b>2</b> containing flexible oligoether chains. These molecules are comprised of <i>m</i>-terphenyl and biphenyl groups, along with triple bonds, and possess lateral methyl or butyl groups at the coil or rod segments. The results of this study suggest that the morphology of supramolecular aggregates is significantly influenced by the lateral alkyl groups and by the sequence of the rigid fragments in the bulk and in aqueous solution. The molecules with different coils self-assemble into lamellar or oblique columnar structures in the bulk state. In aqueous solution, molecule <b>1a</b>, with a lack of lateral groups, self-assembled into large strips of sheets, whereas exquisite nanostructures of helical fibers were obtained from molecule <b>1b</b>, which incorporated lateral methyl groups between the rod and coil segments. Interestingly, molecule <b>1c</b> with lateral butyl and methyl groups exhibited a strong self-organizing capacity to form helical nanorings. Nanoribbons, helical fibers, and small nanorings were simultaneously formed from the <b>2a</b>–<b>2c</b>, which are structural isomers of <b>1a</b>, <b>1b</b>, and <b>1c</b>. Accurate control of these supramolecular nanostructures can be achieved by tuning the synergistic interactions of the noncovalent driving force with hydrophilic–hydrophobic interactions in aqueous solution.