Effect of stereoisomerism on self-assembly and emulsifying mechanism of sugar fatty acyl molecular gelators

The assembly and emulsifying mechanism of supramolecular, stereoisomeric sugar fatty acyl molecular gelators were evaluated. In house synthesized mannitol dioctanoate (M8) and sorbitol dioctanoate (S8) were tested. The stereoisomeric difference between the sugar groups significantly affected the gelation and emulsifying properties of the gelators. This difference had shown significant impact on the physical, thermal, and mechanical properties of their resulting oleogels. The effect of such a stereoisomeric molecular difference on assembly and emulsification mechanism of supramolecular assemblies are intriguing. Henceforth, a detailed investigation was conducted in this study to evaluate the emulsifying nature of molecular gelators. M8 and S8 formed oleogels at 2% and 3.5% (w/v) and emulsified water up to 30% and 60% (v/v), respectively. Microscopy showed that the gelator fibers are at the W/O interfaces, demonstrating the solid particle or network mode of stabilization. The long fibers of M8 were unable to completely encompass the water droplets and resulted in poor emulsification. Small, hair-like fibers of S8 showed better emulsification. This study proved that a subtle stereoisomeric difference at the molecular level can greatly alter the supramolecular and emulsifying properties of sugar-fatty acyl compounds.