Synthesis and characterization of pentaerythritol derived glycoconjugates as supramolecular gelators
Carbohydrate based self-assembling supramolecular systems are important classes of new materials with many potential applications. In this study, a series of branched 1,2,3-triazole based glycoconjugates were synthesized and characterized in order to assess the effect of covalently linking multiple units of sugars. The properties of these twelve compounds gave insight into rational design of effective supramolecular gelators. These glycoconjugates are covalently linked monomeric, dimeric, trimeric, and tetrameric version of glycosyl triazole derivatives. They were synthesized by copper (I) catalyzed azide alkyne cycloaddition reactions (CuAACs) using pentaerythritol as the central building block. These compounds were screened for gelation properties and many of them were found to be effective gelators for alcohols and alcohol water mixtures. In addition, two of the glycoconjugates formed hydrogels in water. We found that the trivalent and tetravalent glycoclusters were effective molecular gelators, but the monovalent and divalent derivatives typically were not able to form gels in the tested solvents. The gels were characterized using rheology and optical microscopy. The trimeric hydrogelator 21 was discovered to be a suitable gelator for encapsulation of naproxen, vitamin B2, and vitamin B12. The strategy of covalently linking three or four small molecules to form trimeric or tetrameric branched compounds is a valid approach in designing useful self-assembling materials. The glycocluster based organogels and hydrogels obtained in this study have potential applications in biomedical research and as advanced functional materials.