Unsaturation effect on gelation behavior of aryl glycolipids

Structurally simple, renewable-resource-based cardanyl (glucoside)s [1, 1-O-3'-n-(pentadecyl) phenyl-beta-D-glucopyranoside; 2, 1-O-3'-n-(8'(Z)-pentadeceenyl)-beta-glucopyranoside; 3, 1-O-3'-n-(8'(Z),11'(Z)pentadecadienyl)phenyl-beta-D-glucopyranoside, 4; 1-O-3'-n-(8'(Z),11'(Z),14'-pentadecatrienyl)phenyl-beta-D-glucopyranoside; and the mixture 5] form thermally reversible transparent gels in a water/alcohol mixture and a number of organic solvents, strongly influenced by the unsaturation of the aliphatic alkyl chain. DSC studies revealed that the Tgel of 1 in water/ethanol (1:1, vol/vol) gel is 69.0 degrees C, while of the introduction of a single double bond reduces the value to 30.0 degrees C in the case of monoene 2, indicating that the stability of the gel is related to the number of double bonds on the lipophilic part of the gelator. Furthermore, XRD measurements showed that the aqueous gel 1 maintains an interdigitated bilayered structure with 3.14 nm long-range ordering, and the corresponding organogel maintains an extended bilayer structure for 4.34 nm, indicating a clear difference in the aggregation behavior in different solvents.