Partially Acetylated or Benzoylated Arabinose Derivatives as Structurally Simple Organogelators: Effect of the Ester Protecting Group on Gel Properties

Abstract

Sugar-based low-molecular-weight gelators (LMWGs) have been used for various applications for a long time. Herein, structurally simple, ester-protected arabinosides are reported as low-molecular-weight organogelators (LMOGs) that are able to gel aromatic solvents, as well as petrol and diesel. Studies on the mechanical strength of the gels, through detailed rheological experiments, indicate that gels from the 1,2-dibenzoylated arabinose gelator possess better mechanical properties than those from the 1,2-diacetylated gelator. These results are interpreted in terms of the tendency of the former to form fibers with comparatively lower diameter than those of the latter, based on detailed field-emission SEM and AFM studies. Investigations of the interactions responsible for the self-assembly of gelators through IR spectroscopy and wide-angle X-ray scattering reveal that the primary interactions responsible are hydrogen bonds between the hydroxyl groups and ester C=O, which is absent in the solid state of the gelators. In addition, π interactions present in the 1,2-dibenzoylated derivative result in a more regular arrangement, which, in turn, leads to better mechanical properties of the gels compared with those of the 1,2-diacetylated gelator.

Carbohydrate Derived Organogelators and the Corresponding Functional Gels Developed in Recent Time

“…Yadav and coworkers have recently shown that arabinose-based partially-protected esters were able to congeal aromatic solvents as well as petrol and diesel [61], and that H-bonds between the OH and ester C=O are primary interactions towards gelation, as established by IR and wide-angle X-ray scattering. In the 1,2-dibenzoylated arabinose system π-interactions play an important role, causing more regular arrangement and better mechanical properties compared to those of the corresponding acetyl derivatives.…”

Structure–gelation property relationships of phenolic glycosides of pentose sugars: pH dependent controlled release of curcumin

“…We had previously reported a simple phenolic glycoside of arabinose as an organogelator 20 as part of our ongoing work on the design of arabinose based gelators. [21][22][23] To gain a better understanding of the structuregelation property relationship of these classes of monosaccharides, we have investigated and herein report the same for the phenolic glycosides of pentose sugars (Fig. 1).…”

Synthesis and Gelling Abilities of Polyfunctional Cyclohexane-1,2-dicarboxylic Acid Bisamides: Influence of the Hydroxyl Groups

“…Otherwise, regarding polyhydroxylated organogelators, only few results on modified carbohydrate or cholestane derivatives have been described and their ability to gelate organic solvents has been interpreted by using different techniques in each case [27,28,29,30]. Nevertheless, as far as we know, there is neither information in the literature on polyhydroxylated simple cycloalkane derivatives nor on compounds susceptible of additional hydrogen-bonding promoted by further functional groups such as amides.…”