Hydrogel behavior of a sugar-based gelator by introduction of an unsaturated moiety as a hydrophobic group.
The new sugar-based gelators 1 and 2 were synthesized, and their gelation abilities were evaluated in organic solvents and in water. Compound 1 gelates both water and organic solvents whereas 2 gelates only organic solvents. Superstructural difference between hydrogel 1 and organogel 2 was investigated by CD, TEM, AFM, 1H NMR and XRD. Hydrogel 1 displays a well-developed helical ribbon structure with 20-150 nm diameter and a length of several hundred microm whereas organogel 2 shows a twisted fiber structure of diameter 20 nm. CD measurements of hydrogel 1 and organogel 2 indicate that hydrogel 1 maintains a well-ordered chiral structure whereas organogel 2 maintains a relatively disordered chiral structure. The 1H NMR and XRD results suggest that the hydrophobic interaction in hydrogel 1 are relatively weak, with a relatively small region interdigitated between lipophilic alkyl groups. In addition, upon irradiation at 254 nm wavelength, hydrogel 1 reveals a red coloration at 540 nm. These results indicate that the self-assembled hydrogel 1 was polymerized by UV-irradiation. The intensity of the CD spectrum of the polymerized hydrogel markedly decreased. This result indicates that upon polymerization the highly ordered chiral structure of hydrogel 1 changes to a disordered molecular packing structure.
Jung
Jong Hwa
JH
Department of Chemistry, Research Institute of Natural Science, Gyeongsang National University, Chinju 660-701, S. Korea.
Rim
Jeong Ah
JA
Han
Won Seok
WS
Lee
Soo Jin
SJ
Lee
Young Joo
YJ
Cho
Eun Jin
EJ
Kim
Jong Seung
JS
Ji
Qingmin
Q
Shimizu
Toshimi
T