Formation of High-Axial-Ratio Microstructures from Sugar-, Peptide-, and Nucleobase-based Bolaamphiphiles

A variety of bola-form amphiphiles (bolaamphiphiles), in which sugar, peptide, or nucleobase moieties are connected to both ends of a hydrocarbon spacer, were synthesized. These compounds self-assembled in aqueous solution to form thermally stable, nanometer-scale high-axial-ratio microstructures (HARMs), such as helical fibers, tubular fibers, and double-helical ropes. Size distribution of the structures was essentially the same as that of self-assembled fibrous structures like collagen fibers, flagella, and actin fibers and morphology was found to strongly depend on chain length and even-odd carbon number of used oligomethylene spacers. Molecular arrangement and hydrogen bond networks within HARMs were investigated by FT-IR, XRD, and AFM. Interlayer and intralayer interactions of the monolayers were noted to be major determinants of fiber morphology. HARMs are constructed hierarchically in a manner similar to biological structures.