One of the most fascinating subjects in areas such as nanoscience and biomimetic chemistry is concerned with the construction of novel supramolecular nanoscopic architectures with well defined shapes and functions. Supramolecular assemblies of aromatic rod molecules provide a facile entry into this area. Aromatic rigid rod molecules consisting of hydrophilic flexible chains, in aqueous solution can self-assemble into a variety of supramolecular structures through mutual interactions between aromatic rod molecules and water, including hydrophobic and hydrophilic interactions and pi-pi interaction. The supramolecular architecture in water can be manipulated by variation of the shape of the rigid segments, as well as the relative volume fraction of the flexible segment. The rigid aromatic segments have significant photonic and electronic properties. The self-assembly of aromatic rod molecules in water, therefore, can provide a strategy for the construction of well-defined and stable nanometer-size structures with chemical functionalities and physical properties as advanced materials for photonic, electronic and biological applications.

Carbohydrate conjugate rod-coil amphiphiles were synthesized and their self-assembling behavior in aqueous solution was investigated. These amphiphiles were observed to self-assemble into supramolecular structures that differ significantly depending on the molecular architecture. The rod-coil amphiphiles based on a short coil (1) self-assemble into a vesicular structure, while the amphiphiles with a long coil (2) show a spherical micellar structure. In contrast, 3, based on a twin-rod segment, was observed to aggregate into cylindrical micelles with twice the diameter of molecular length scale. As a means to determine the binding activity to protein receptors of these supramolecular objects, hemagglutination inhibition assay was performed. The experiments showed that the supramolecular architecture has a significant effect on the binding activity. In addition, incubation experiments with Escherichia coli showed that mannose-coated objects specifically bind to the bacterial pili of the ORN 178 strain. These results demonstrate that precise control of the nano-objects in shape and size by molecular design can provide control of the biological activities of the supramolecular materials.

A series of achiral rod-coil molecules consisting of an oligo(p-phenylene) conjugated rod with a poly(ethylene oxide) or poly(propylene oxide) coil laterally attached through an imidazole linkage were synthesized, and their interfacial behaviors were investigated. Compounds 1a and 1b have a similar surface behavior with a shoulder indicating a transformation of rod segments from flat-on to vertical orientation. Interestingly, CD and AFM suggest chiral films are formed when the LB films were deposited after the shoulder. Although compound 1c shows different surface behavior because the PEO chains dissolved into water upon compression, macroscopic chirality was also detected. In contrast, compound 2, based on a reduced conformational rigidity of the aromatic rod segment, does not form chiral assemblies. Combining the data collected, the cooperative interaction of the hydrogen bond between the molecules and pi-pi stacking as well as the steric constraint between the aromatic rod segments are responsible for the macroscopic chirality. Such kind of stacking can be realized through a molecular design and a lateral compression. A deep insight into the relationship between the molecular structure and the chirality was gained.

Solid scrolls are reversibly formed by self‐assembly of rod‐shaped molecules with laterally attached coil units, in contrast to the layered structures formed from self‐assembly of planar molecules. As described by M. Lee and co‐workers in their Communication on the core structure of the scrolls, which are either filled cylinders or hollow tubes, can be controlled by variation of the length of the coil unit. The cover picture shows aligned tubular scrolls displaying well‐defined in‐plane ordering of the rod segments.

Novel block facial amphiphiles consisting of a laterally extended aromatic segment and oligo(ethylene oxide) dendrons as a flexible segment were synthesized in a stepwise fashion and their aggregation behavior was investigated in aqueous solution; self-assembly into elongated nanofibers with a uniform diameter of 7 +/- 0.5 nm and lengths up to several hundred nanometers was observed.