Development of Novel Low-Molecular-Mass Oil-gelling Agents: Synthesis and Physical Properties of 1,5-Anhydro-D-glucitol and 1,5-Anhydro-D-mannitol Protected with Saturated Linear Fatty Acids

Abstract

We have developed a novel low-molecular-mass oil-gelling agent that is electrically neutral, has no nitrogen atoms and consists only of cyclic sugar alcohols and saturated linear fatty acids. The cyclic sugar alcohols were 1,5-anhydro-D-glucitol (1,5-AG) and 1,5-anhydro-D-mannitol (1,5-AM) derived from starch via 1,5-anhydro-D-fructose. Various saturated linear fatty acids with 10 to 18 and 22 carbon atoms were introduced into all the hydroxy groups of 1,5-AG. Various saturated linear fatty acids with 13 to 18 and 22 carbon atoms were introduced into all the hydroxy groups of 1,5-AM. Initially, the gelling ability increased as the carbon number increased, but the gelling ability decreased as the carbon number increased beyond 17 carbons. This trend was similar for both 1,5-AG and 1,5-AM. A comparison of 1,5-AG and 1,5-AM derivatives revealed that 1,5-AG derivatives had greater gelling abilities for different kinds of oils at the same fatty acid length. Further, it was confirmed by SEM observations that a three-dimensional fibrous structure was formed, and this network structure formed the gel and held the oil. Here, we report the synthesis and characteristics of a novel lowmolecular-weight gelling agent and its gelation mechanism.

Development of Low-Molecular-Mass Organogelators: Synthesis and Physical Properties of N-Linear Saturated Fatty Acyl-GABAs and Their Ester Derivatives

“…and H-1ax), 3.59 (ddd, 1H, J 4,5 10.0 Hz, J 5,6′ 4.2 Hz, J 5,6 2.2 Hz, H-5), 4.08 (dd, 1H, J gem 12.4 Hz, J 5,6 2.1 Hz, H-6), 4.14 (dd, 1H, J gem 11.3 Hz, J 1eq,2 5.7 Hz, H-1 eq), 4.32 (dd, 1H, J gem 12.4 Hz, J 5,6′ 4.3 Hz, H-6′), 4.99−5.05 (m, 1H, H-2), 5.03 (t, 1H, J 3,4 = J 4,5 9.5 Hz, H-4), 5.18 (t, 1H, J 2,3 = J 3,4 9. 4 Hz, H-3), 5.82 (t, 1H, J NH,CH 2 5.6 Hz, NH), 5.99 (t, 1H, J NH,CH 2 5.8 Hz, NH), 6.21 (t, 1H, J NH,CH 2 5.8 Hz, NH), 6.22 (t, 1H, J NH,CH 2 5.9 Hz, NH); 13 C NMR (100 MHz, CDCl 3 ): δ 14.11 (C lipid -12), 22.69 (C lipid -11), 24.49 (C GABA -3), 24.52 (C GABA -3), 24.60 (C GABA -3), 24.68 (C GABA -3), 25.80 (C lipid -3), 25.81 (C lipid -3), 25.82 (C lipid -3), 29.35−29.67 ( 3.2.2. 1,5-Anhydro-2,3,4,6-tetra-O-{4-[(1-oxotetradecyl)amino]butanoyl}-D-glucitol (6: C 14 GABA-AG).…”

“…Similarly, we have already reported that the hardness of C16AG gels increases up to 16 carbons and decreases with further extension from 16. 4 Unfortunately, the cause of these decreases…”

“…In our previous work, we reported that C16AG, a palmitic acid bound to 1,5-AG, is a good organogelator. 4 This showed that the chiral compound 1,5-AG can sterically fix the position of the palmitic acid and strongly induce stacking between molecules to form a fibrous structure. In compounds 5−8, we speculate that the hydrogen bonding of the amide group in the alkyl chain strongly induces intermolecular stacking.…”

Supramolecular Organogelation Directed by Weak Noncovalent Interactions in Palmitoylated 1,5‐Anhydro‐d‐Glucitol Derivatives

“…Syntheses of acetylated derivatives: 2AC16AG, 3AC16AG, 4AC16AG, and 6AC16AG were obtained by acetylation of 1,5anhydro-d-glucitol tripalmitates 2OH16AG, 3OH16AG, 4OH16AG, and 6OH16AG (Scheme S1), which formed as byproducts in the synthesis of 1,5-anhydro-d-glucitol-2,3,4,6-O-tetrapalmitate (16AG) from 1,5-anhydro-d-glucitol, as reported previously. [15] 1,5-Anhydrod-glucitol-2,3,4,6-O-tetraacetate (ACAG) was synthesized by acetylation of 1,5-anhydro-d-glucitol.…”

“…In previous work, we enzymatically synthesized 1,5-anhydro-d-glucitol, which does not have the 1-hydroxyl group, from starch as a raw material and esterified it with palmitoyl chloride to obtain 2,3,4,6-tetrapalmitoylated 1,5anhydro-d-glucitol derivative 16AG (Figure 1). [15] Interestingly, 16AG self-assembles into fibers and gelatinizes various kinds of organic solvents even though it has no conventional hydrogenbonding sites. In this study, we determined the structure of the self-assembled fibers and explored the gelation behavior and…”