Self-assembly of π-conjugated gelators into emissive chiral nanotubes: emission enhancement and chiral detection.

A series of new π-conjugated gelators that contain various aromatic rings (phenyl, naphthyl, 9-anthryl) and amphiphilic L-glutamide was designed, and their gel formation in organic solvents and self-assembled nanostructures was investigated. The gelators showed good gelation ability in various organic solvents that ranged from polar to nonpolar. Those gelator molecules with small rings such as phenyl and naphthyl self-assembled into nanotube structures in most organic solvents and showed strong blue emission. However, the 9-anthryl derivative formed only a nanofiber structure in any organic solvent, probably owing to the larger steric hindrance. All of these gels showed enhanced fluorescence in organogels. Furthermore, during the gel formation, the chirality at the L-glutamide moiety was transferred to the nanostructures, thus leading to the formation of chiral nanotubes. One of the nanotubes showed chiral recognition toward the chiral amines.