Controlled Helicity of the Rigid-Flexible Molecular Assembly Triggered by Water Addition: From Nanocrystal to Liquid Crystal Gel and Aqueous Nanofibers

Despite recent advances in synthetic nanometer-scale helical assembly, control of supramolecular chirality remains a challenge. Here, we describe the fine-tuning of the shape and morphology transitions of twisted and helical assembly from dumbbell-shaped rigid-flexible amphiphile triggered by concentration. The amphiphile 2 self-assembles into nonchiral 3D columnar crystals with alternative packing of aromatic segment in solid state. Remarkably, with the addition of water into the solid, the achiral crystal transforms into 2D hexagonally ordered liquid crystal gel with supramolecular chirality due to increased entropy of flexible coil in aqueous environment. Notably, the helical liquid crystal gel was observed to dissolve into optically active aqueous nanofibers caused by a conformational change of hydrophobic aromatic rods and enhanced hydro-volume of the ethylene oxide chains.