New dicholesteryl-based gelators: chirality and spacer length effect.
New dicholesteryl-based gelators: chirality and spacer length effect.
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DOI：
10.1021/la703672u
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发表时间：
2008-02
期刊：
影响因子：
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通讯作者：
Junxia Peng;Kaiqiang Liu;Jing Liu;Qiuhong Zhang;Xuli Feng;Yu Fang
中科院分区：
文献类型：
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作者：
Junxia Peng;Kaiqiang Liu;Jing Liu;Qiuhong Zhang;Xuli Feng;Yu Fang
设计并制备了八种新的L(D)-丙氨酸二胆固醇酯二酰胺。间隔基含有3、4、5或6个碳原子和L-丙氨酸残基的化合物分别表示为1a、2a、3a和4a，含有D-丙氨酸残基的化合物分别表示为1b、2b、3b和4b。凝胶测试表明，间隔基长度的细微变化和氨基酸残基手性的倒转可以使化合物的凝胶行为和凝胶的微观结构发生巨大变化，如 SEM、XRD 和 CD 测量所示。重要的是，对于化合物 1 和 2，那些含有 d-丙氨酸残基 (1b, 2b) 的凝胶剂比其具有相反手性的类似物 (1a, 2a) 更有效。然而，对于较长间隔基(3、4)的化合物，含有L-丙氨酸残基(3a、4a)的化合物优于含有d-丙氨酸残基(3b、4b)的相应化合物。非常有趣的是，在研究的 139 个凝胶系统中，至少有 11 个在室温下自发凝胶。对这些凝胶示例系统的流变性质的研究表明，胶凝剂间隔长度的变化对相应凝胶的机械性质有很大影响，并且研究还揭示了凝胶的触变性质。此外，观察到通过在室温下简单搅拌系统，4a 与一些有机溶剂形成油包水凝胶乳液。
Eight new diacid amides of dicholesteryl L(D)-alaninates were designed and prepared. The compounds with spacers containing three, four, five, or six carbon atoms and L-alanine residues are denoted as 1a, 2a, 3a, and 4a, respectively, and those containing D-alanine residues are denoted as 1b, 2b, 3b, and 4b, respectively. A gelation test revealed that a subtle change in the length of the spacer and an inverse in the chirality of the amino acid residue can produce a dramatic change in the gelation behavior of the compounds and the microstructures of the gels, as revealed by SEM, XRD, and CD measurements. Importantly, for the compounds 1 and 2, those containing d-alanine residues (1b, 2b) are more efficient gelators than their analogues with opposite chirality (1a, 2a). For the compounds of longer spacers (3, 4), however, those containing l-alanine residues (3a, 4a) are superior to the corresponding ones with d-alanine residues (3b, 4b). Very interestingly, of the 139 gel systems studied, at least 11 of them gel spontaneously at room temperature. Studies of the rheological properties of the example systems of these gels demonstrated that change in the spacer lengths of the gelators has a great effect upon the mechanical properties of the corresponding gels, and the studies also revealed the thixotropic properties of the gels. Furthermore, it was observed that 4a forms water-in-oil gel emulsions with some organic solvents by simple agitating the systems at room temperature.