Synthesis, Characterization and Application of Sugar-Based Low Molecular Weight Gelators

Low molecular weight gelators (LMWGs) are an interesting class of compound that have gained considerable attention especially because of their potential applications for soft biomaterials. Carbohydrate based low molecular weight hydrogelators and organogelators are able to selfassemble and form ordered supramolecular structures, which are useful for exploring biomedical applications. The resulting gelators are responsive to external stimuli because of the weak noncovalent intermolecular forces and interaction that influences self-assembly. Stimuli-responsive supramolecular organogels with interesting properties in response to external environmental stimuli have gained considerable attention due to their applications in biomaterials, sensors and for drug delivery. One of the major challenges in the field of small molecule gelation is understanding the mechanism of gelation. Consequently, the use of structural templates in the design and synthesis of LMWGs cannot be over emphasized. A review of the recent progress that has been made in the design and application of LMWGs will be discussed. This dissertation will also highlight some of the work that have been done in our research group. This dissertation also explores the investigation of the influence of different substituent in the anomeric position on carbohydrate on gelation and the influence of different functional groups such as triazole, urea and amide on gelation. Previously, we have shown that α-O-methyl-Dglucosamine derived amides and ureas are effective low molecular weight gelators. In order to understand the structural requirement for the self-assembling and the gelation properties, a series of α-O-butyl-D-glucosamine derived amides and ureas were synthesized and characterized using rheology, optical microscope and NMR studies. The synthesis and gelation property study of a series of peracetylated lactose and maltose triazole derivatives will also be discussed. Results from this study showed that the maltosyl based triazole derivatives were effective gelators while the lactosyl based triazole derivatives were poor gelators. NMR studies also showed that theconfiguration of the sugar moiety played a significant role towards gelation. Furthermore, to discover smart organogelators with built-in functionality that would be responsive to external stimuli, a series of sugar based UV and pH responsive organogels were synthesized. The compounds were characterized using NMR and LCMS. The gelation ability of the compoundswas characterized in various solvents including non-polar solvents, polar solvents and a mixture of solvents. The resulting gels were observed to be stable but the gel matrix was disrupted when exposed to UV light and in basic pH solutions