Hydrogel behavior of a sugar-based gelator by introduction of an unsaturated moiety as a hydrophobic group
作者:Jong Hwa Jung、Jeong Ah Rim、Won Seok Han、Soo Jin Lee、Young Joo Lee、Eun Jin Cho、Jong Seung Kim、Qingmin Ji、Toshimi Shimizu
DOI:10.1039/b602279k
日期:——
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 µm 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.
合成了新的糖基凝胶剂 1 和 2,并评估了它们在有机溶剂和水中的凝胶能力。化合物 1 在水和有机溶剂中都能凝胶,而化合物 2 只能在有机溶剂中凝胶。通过 CD、TEM、AFM、1H NMR 和 XRD 研究了水凝胶 1 和有机凝胶 2 的超结构差异。水凝胶 1 显示出发达的螺旋带状结构,直径为 20-150 纳米,长度为几百微米,而有机凝胶 2 显示出直径为 20 纳米的扭曲纤维结构。对水凝胶 1 和有机凝胶 2 进行的 CD 测量表明,水凝胶 1 保持了良好的手性结构,而有机凝胶 2 则保持了相对无序的手性结构。1H NMR 和 XRD 结果表明,水凝胶 1 中的疏水作用相对较弱,亲油烷基之间有一个相对较小的交错区域。此外,在 254 纳米波长的照射下,水凝胶 1 在 540 纳米波长处呈现红色。这些结果表明,自组装水凝胶 1 是通过紫外线照射聚合而成的。聚合水凝胶的 CD 光谱强度明显降低。这一结果表明,聚合后水凝胶 1 的高度有序手性结构变为无序分子堆积结构。