Self-Assembly of Achiral Shape Amphiphiles into Multi-Walled Nanotubes via Helicity-Selective Nucleation and Growth

Soft nanotubes are normally constructed from chiral amphiphiles through helical self-assembly. Yet, how to self-assemble achiral molecules into nanotubes is still a challenge. Here, we report the nanotube construction with achiral shape amphiphiles through helical self-assembly and also unravel the formation mechanisms. The amphiphiles have a dumbbell shape and are composed by covalently linking three achiral moieties together: two unlike clusters and an organic tether. The difference in polarity between the unlike clusters drives the amphiphiles to self-assemble into single- and multi-walled nanotubes as well as intermediates. Analysis of the key intermediates unravels the self-assembly mechanism of helicity-selective nucleation and growth. Meanwhile, direct visualization of the individual clusters in the ribbons displays a two-dimensional deformed hexagonal lattice. Thus, we speculate that it is the lattice deformation that creates anisotropic tension along different directions of the ribbon which further results in the formation of helical ribbons towards nanotubes by amphiphiles.