Mild One-Step Synthesis of 4,6-Benzylideneglycopyranosides from Aromatic Aldehydes and Gelation Abilities of the Glucose Derivatives

We report herein an efficient one-step synthesis of 4,6-benzylidene glycoside derivatives from aromatic aldehydes bearing electron-donating or -withdrawing groups as well as polymerisable monomer groups. Glucose, mannose and galactose derivatives could also be used successfully. Several of the glucose derivatives thus obtained acted as gelators for various solvents, including water. 4-(n-Butoxybenzylidene)glucose derivative 3a produced both a clear squalane gel and a hydrogel at 0.1 wt.-%. Furthermore, 3-(n-butoxybenzylidene)glucose derivative 3i produced a clear organogel and an opaque hydrogel. The critical gelation concentration (CGC) of 3i in squalane was determined to be 0.02 wt.-%, which is one of the lowest CGC values reported so far. The organogels, hydrogels and aqueous solution gels produced from 3a and 3d exhibited thixotropy. The strength and thixotropy of the organo- and hydrogel produced from 3a were estimated by a rheometer. The gel morphologies were observed by field-emission and wet-scanning electron microscopy, and the self-assembly modes were analysed by XRD. We have concluded that super-gelators can be created by this method.