Amphiphilic coil–rod–coil molecules 1–3, 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 1 self-assembles into lamellar and hexagonal perforated layer structures, in the crystalline and liquid crystalline phases, respectively. Remarkably, molecule 2 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 2 generates molecule 3, which assumes an exclusively oblique columnar structure in the solid state. In aqueous solutions, molecule 1 self-assembles into fibrous aggregates, whereas molecules 2 and 3 exhibit a self-organizing capacity to form helical fibers. Additionally, circular dichroism (CD) experiments and atomic force microscope (AFM) measurements of molecule 3 highlight a switch of the helical sense to the opposite handedness, depending on the temperature of the aqueous solution.

Rigid-flexible amphiphilic molecules consisting of an aromatic segment based on pyrene and biphenyl units and hydrophilic polyethylene oxide chains self-assemble into lamellar, hexagonal columnar, and two-dimensional columnar nanostructures in the bulk state. In aqueous solution, these molecules self-assemble into nanofibers, spherical micelles, and multilayer nanotubes, depending on the chain or rod length of the molecules. Notably, ordered nanostructures of supramolecular polymers, such as single-layer curving fragments, nanofibers, and nanosheets, were constructed through charge-transfer interactions between the nanoobjects and an electron-acceptor molecule, 2,4,5,7-tetranitrofluorenone. These experimental results reveal that diverse supramolecular morphologies can be controlled by tuning rod-coil molecular interactions or charge-transfer interactions between the donor and acceptor molecules.

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 1-2 containing flexible oligoether chains. These molecules are comprised of m-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 1a, with a lack of lateral groups, self-assembled into large strips of sheets, whereas exquisite nanostructures of helical fibers were obtained from molecule 1b, which incorporated lateral methyl groups between the rod and coil segments. Interestingly, molecule 1c 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 2a-2c, which are structural isomers of 1a, 1b, and 1c. 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.

Self-assembled nanomaterials composed of amphiphilic oligomers with functional groups have been applied in the fields of biomimetic chemistry and on-demand delivery systems. Herein, we report the assembly behavior and unique properties of an emergent n-shaped rod–coil molecule containing an azobenzene (AZO) group upon application of an external stimulus (thermal, UV light). The n-shaped amphiphilic molecules comprising an aromatic segment based on anthracene, phenyl linked with azobenzene groups, and hydrophilic oligoether (chiral) segments self-assemble into large strip-like sheets and perforated-nanocage fragments in an aqueous environment, depending on the flexible oligoether chains. Interestingly, the nano-objects formed in aqueous solution undergo a morphological transition from sheets and nanocages to small one-dimensional nanofibers. These molecules exhibit reversible photo- and thermal-responsiveness, accompanied by a change in the supramolecular chirality caused by the conformational transitions of the rod backbone. The architecture of n-shaped amphiphilic molecules with a photosensitive group makes them ideal candidates for intelligent materials for applications in advanced materials science.

Ordered supramolecular nanstructures of rod–coil molecular isomers were created by tuning the sequence of rod segments and altering the type of coil chain in bulk and in aqueous solution.