Controllable hierarchical self-assembly of gemini supra-amphiphiles: the effect of spacer length

Gemini supra-amphiphiles with different spacer lengths, [M-n-M](2+)@2[DBS](-) (n = 2, 6, 10), were easily constructed. The conformational flexibility and hydrophobicity of the spacer group can be effectively tailored through regulating the spacer length, leading to the fine control of the topologies and subsequent hierarchical self-assemblies of [M-n-M](2+)@2[DBS](-). Vesicles are primarily fabricated by [M-n-M](2+)@2[DBS](-), and then successively fused into vesicle clusters, nanotubes, and planar bilayers, whose bilayer curvatures are gradually decreased, with increasing spacer length. Coating [M-10-M](2+) with beta-CD can reduce the flexibility and hydrophobicity of the decyl spacer, resulting in the reversion from planar bilayers to vesicles. Furthermore, stable aqueous two-phase systems (ATPSs) that spontaneously formed via vesicle fusion in the solutions of [M-n-M](2+)@2[DBS](-) (n = 6, 10) can act as functional supramolecular systems in the isolation and purification of oil-soluble biomaterials.