Synthesis of d-glucono-1,4-lactones modified with linear saturated fatty acids as novel low molecular-weight organogelators and evaluation of their physical properties†

To develop a novel low molecular-weight organogelator, D-glucono-1,4-lactones were synthesized with all hydroxy groups esterified with linear saturated fatty acids, and their gelation ability was evaluated. When a fatty acid was introduced, the six-membered ring D-glucono-1,5-lactone transformed into a five-membered ring D-glucono-1,4-lactone, regardless of the length of the fatty acid. However, the gelation ability depended on the length of the fatty acid, and compounds esterified with palmitic acid (16 carbons) and stearic acid (18 carbons) showed a better gelation ability. Electron microscopy showed that the structure of the xerogels varied with the length of the fatty acids. Some xerogels formed fibrous structures and others formed plate-like crystals, building up to a porous structure. In addition to their physical properties as an organogelator, their emulsification ability and crystal polymorphism were confirmed, and detailed polymorphic crystal analysis through FT-IR was performed to estimate the intermolecular packing structure at the molecular level.