From achiral to helical bilayer self-assemblies of a 1,3,5-triazine-2,4,6-triphenol-grafted polyanionic cluster: countercation and solvent modulation.

A triazine derivative with two short alkyl chains was covalently grafted onto a disk-like polyoxometalate cluster on both sides, and an amphiphilic polyanionic cluster was obtained. The linear cluster complex showed phase separation in polar and non-polar solutions and self-assembled into spherical, planar, and helical aggregates in turn with the solution polarity decreasing from the methanol/water to the chloroform/n-hexane mixture. Accompanied by morphological changes, the self-assembled bilayer structure varied from a regular bilayer structure either partially or fully, to an over interdigitated bilayer structure and finally to a partially inverse interdigitated bilayer structure. Moreover, induced chirality took place and was amplified in the helical assembly via the modulation of counter-cations and solvent polarity.