Self-Assembly of n‑Shaped Rod–Coil Molecules into Thermoresponsive Nanoassemblies: Construction of Reversible Helical Nanofibers in Aqueous Environment

Amphiphilic coil–rod–coil molecules <b>1</b>–<b>3</b>, consisting of an n-shaped rod building block and poly­(ethylene oxide) (PEO) with a degree of polymerization of 5 linked through a biphenyl unit as the coil segment, were synthesized. Molecule <b>1</b> self-assembles into lamellar and hexagonal perforated layer structures, in the crystalline and liquid crystalline phases, respectively. Remarkably, molecule <b>2</b> incorporating lateral methyl groups between the rod and coil segments spontaneously self-organizes into hexagonal perforated layer and oblique columnar structures. The additional incorporation of a lateral butyl group at the center of the rod segment of molecule <b>2</b> generates molecule <b>3</b>, which assumes an exclusively oblique columnar structure in the solid state. In aqueous solutions, molecule <b>1</b> self-assembles into fibrous aggregates, whereas molecules <b>2</b> and <b>3</b> exhibit a self-organizing capacity to form helical fibers. Additionally, circular dichroism (CD) experiments and atomic force microscope (AFM) measurements of molecule <b>3</b> highlight a switch of the helical sense to the opposite handedness, depending on the temperature of the aqueous solution