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Spectral Characterization of Self‐Assemblies of Aldopyranoside Amphiphilic Gelators: What is the Essential Structural Difference Between Simple Amphiphiles and Bolaamphiphiles?
Author(s) -
Jung Jong Hwa,
Shinkai Seiji,
Shimizu Toshimi
Publication year - 2002
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20020617)8:12<2684::aid-chem2684>3.0.co;2-z
Subject(s) - amphiphile , lamellar structure , aqueous solution , bilayer , alkyl , chemistry , chemical engineering , self assembly , crystallography , materials science , polymer chemistry , organic chemistry , membrane , polymer , copolymer , biochemistry , engineering
An aldopyranoside‐based gelators (dodecanoyl‐ p ‐aminophenyl‐ β ‐ D ‐aldopyranoside)s and [1,12‐dodecanedicarboxylic‐bis( p ‐aminophenyl‐ β ‐ D ‐aldopyranoside)]s 1 – 4 were synthesized, and their gelation ability was evaluated in organic solvents and water. Simple aldopyranoside amphiphiles 1 and 2 were found to gelate organic solvents as well as water in the presence of a small amount of alcoholic solvents. More interestingly, not only extremely dilute aqueous solutions (0.05 wt %) of the bolaamphiphiles 3 and 4 , but solutions of 3 and 4 in several organic solvents could be gelatinized. These results indicate that 1 – 4 can act as versatile amphiphilic gelators. We characterized the superstructures of the aqueous gels and organogels prepared from 1 – 4 using SEM, TEM, NMR and IR spectroscopy, and XRD. The aqueous gels 1 and 2 formed a three‐dimensional network of puckered fibrils diameters in the range 20–200 nm, whereas the aqueous gels 3 and 4 produced filmlike lamellar structures with 50–100 nm thickness at extremely low concentrations (0.05 wt %). Powder XRD experiments indicate that the aqueous gels 1 and 2 maintain an interdigitated bilayer structure with a 2.90 nm period with the alkyl chain tilted, while the organogels 1 and 2 take a loosely interdigitated bilayer structure with a 3.48 nm period. On the other hand, the aqueous‐ and the organogels 3 and 4 have 3.58 nm spacing, which corresponds to a monolayered structure. The XRD, 1 H NMR and FT‐IR results suggest that 1 – 4 are stabilized by a combination of the hydrogen‐bonding, π–π interactions and hydrophobic forces.