Self-assembly of a sugar-based gelator in water: Its remarkable diversity in gelation ability and aggregate structure

A new sugar-based gelator 1 was synthesized, and its gelation ability was evaluated in organic solvents and water. Very surprisingly, 1 was found to gelate organic solvents as well as water, indicating that 1 can act as an amphiphilic gelator. We characterized on superstructures of an aqueous gel from 1 using SEM, TEM, NMR, III, and XRD. The aqueous gel 1 formed a three-dimensional network with 20-500 nm diameter puckered fibrils. In addition, the chiral aggregate was found to be largely twisted helical ribbons with ca. 85 nm width, ca. 315 nm pitch, and up to several micrometer length, whose helicity was exclusively left-handed. XRD diagrams indicate that an aqueous gel 1 maintains a bilayered structure with 2.90 nm long-range spacing. This gives the first example of the formation of well ordered bilayer-based aqueous gel. The XRD, FT-NMR, and FT-IR results suggested that the aqueous gel 1 is stabilized by a combination of the hydrogen bonding, pi-pi interactions, and hydrophobic forces.