Multiresponsive chiroptical switch of an azobenzene-containing lipid: solvent, temperature, and photoregulated supramolecular chirality.

An azobenzene-containing lipid was designed as a functional organogelator, and its self-assembly as well as the chiroptical properties were investigated. The gelator shows good gelation ability in various organic solvents ranging from polar to nonpolar solvents. Although the molecule did not show a CD signal in the absorption band of azobenzene in solution, supramolecular chirality was observed upon gel formation. Moreover, the supramolecular chirality exhibited a multiresponse to temperature, photoirradiation, and the solvent polarity. Particularly, positive supramolecular chirality was observed in polar solvents, while it inverted to a negative one in nonpolar solvents. All the responses in relating to the supramolecular chirality were reversible and thus produced a multiresponsive chiroptical switch.