Construction of light-responsive phase chirality from an achiral macrogelator

To realize light-responsive phase chirality from an achiral macrogelator in the solid state, a disc-shaped achiral macrogelator (B1AZ) was newly synthesized. B1AZ was self-assembled into a lamello-columnar structure in the bulk state, while single-handed helical fibrils (H_F) with 400 nm of helical pitch were constructed by side-by-side lateral association of achiral B1AZ molecules in carvone chiral solvents. Even after the elimination of chiral solvents, the helical morphology and its chiroptical properties were precisely preserved. However, H_F was not sensitive to UV light due to intense lateral packing. For remote-controlling the helical morphology, a single-helix (H_S) with an 18 nm helical pitch was formed by utilizing cis-B1AZ sol. Upon irradiation with UV light, H_S was transformed into spheroids (S) because of the trans-to-cis photo-isomerization of the azobenzene (AZ) of B1AZ. The photo-switchable phase chirality can be applied in light-responsive smart materials.