Induction of supramolecular chirality in self-assembled nanofibers triggered by environmental change

A carbazole end-capped rod amphiphile was synthesized and observed to self-assemble into non-chiral fibers in both methanol and water solutions even though the molecule contains a chiral oligoether dendron. Remarkably, a mixture of water and methanol induces supramolecular chirality of the nanofibers caused by a conformational change of hydrophobic aromatic rods and reduction in the hydrodynamic volume of the ethylene oxide chains. The helicity induction of the nanofibers also takes place by heating the water solution. Furthermore, the helical fibers in aqueous solution were observed to further aggregate into a rigid gel at higher temperature by enhanced hydrophobic interactions between the dehydrated oligo(ethylene oxide) dendrons.