Facile syntheses of a class of supramolecular gelator following a combinatorial library approach: Dynamic light scattering and small-angle neutron scattering studies
Facile syntheses of a class of supramolecular gelator following a combinatorial library approach: Dynamic light scattering and small-angle neutron scattering studies
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DOI：
10.1021/cm048210o
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发表时间：
2005-02-22
影响因子：
8.6
通讯作者：
Shibayama, M
中科院分区：
文献类型：
--
作者：
Dastidar, P;Okabe, S;Shibayama, M
根据组合库方法，通过5种胆汁酸和12种仲胺反应制备了60种有机盐。用各种有机溶剂和水溶剂进行的甘氨酰试验表明，16种盐是超分子凝胶剂，其中6种盐是双分子的，显示出与有机溶剂和水溶剂形成凝胶的能力。双十二烷基铵胆酸盐（1a 7 b）是最通用的胶凝剂，在最大数量的溶剂下显示出胶凝能力。1a 7 b在有机溶剂和水溶剂中的干凝胶的AFM图像揭示了包括螺旋纤维的纤维聚集体的存在。动态光散射（DLS）和小角中子散射（SANS）实验研究了1a 7 b水凝胶（1：1 DMSO/H2O）中聚集体的动态和形态学行为。结果表明，凝胶化是通过形成柔性纤维簇，然后进行物理交联而发生的。DLS和SANS结果还公开了：（1）纤维网络是通过长度为几十纳米的柔性簇形成的，然后是固定的网络形成;（2）网络结构是自相似的，与胶凝剂浓度C无关，而胶凝温度是C依赖性的;以及（3）纤维聚集体处于具有尖锐边界的固态。
Following a combinatorial library approach, 60 organic salts have been prepared by reacting 5 bile acids and 12 secondary amines. Gelation tests with various organic and aqueous solvents reveal that 16 salts are SUpraniolecular gelators of which 6 salts are found to be ambidextrous displaying the ability to form gels with organic as well as aqueous solvents. The salt didodecylammuonium cholate (1a7b) is the most versatile gelator, displaying gelation ability with a maximum number of solvents. AFM images of the xerogels of 1a7b in organic and aqueous solvents reveal the presence of fibrous aggregate including helical fibers. Dynamic and morphological behaviors of the aggregates in the gel state have been probed by dynamic light scattering (DLS) and small-angle neutron scattering (SANS) experiments on an aqueous gel (1: 1 DMSO/H2O) of 1a7b. It is revealed that the gelation takes place via the formation of flexible fibrous clusters followed by physical cross-linking. DLS and SANS results also disclose that (1) the fibrous network is formed via flexible clusters of a few tens of nanometers in length, followed by immobile network formation; (2) the network structure is self-similar irrespective of gelator concentration, C, while the gelation temperature is C dependent; and (3) the fibrous aggregates are in the solid state with a sharp boundary.