Bottom-up synthesis and structural properties of self-assembled high-axial-ratio nanostructures

Feature Article: Nature allows structural building blocks to hierarchically organize into any structures in atomic order resolution, which are formed spontaneously in bottom-up fashion. Of particular interest is that nanostructures in nature can be constructed with high accuracy and minimum energy. It is, on the contrary, still difficult for mankind to achieve the total synthesis and structural control of macromolecules only by covalent chemical synthesis. The present paper will overview the noncovalent formation of high-axial-ratio nanostructures (HARNs), such as fibers, rods, tubes and ropes, through the self-assembly of bola-form amphiphilic monomers. A variety of bolaamphiphiles in which sugars, peptides, or nucleo-bases are connected to both ends of a, hydrocarbon spacer, were synthesized. Their morphologies proved to strongly depend on the spacer chain lengths and even/odd carbon numbers of the oligo(methylene) spacers used. The presented self-assembled HARNs are constructed hierarchically in a manner similar to biological structures.