Controlled large macrodipoles in a supramolecular polymer of tri-3,7-dimethyloctyl-cis-1,3,5-cyclohexane-tricarboxamide in n-decane
Controlled large macrodipoles in a supramolecular polymer of tri-3,7-dimethyloctyl-cis-1,3,5-cyclohexane-tricarboxamide in n-decane
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DOI：
10.1021/ma051489p
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发表时间：
2005-11-01
期刊：
影响因子：
5.5
通讯作者：
Hanabusa, K
中科院分区：
文献类型：
--
作者：
Sakamoto, A;Ogata, D;Hanabusa, K
在此，我们报告了在正癸烷（C10）中由于3重氢键形成的三- 3,7 -二甲基辛基-顺- 1,3,5 -环己三羧胺（DO3CH）的超分子聚合物中存在高度控制的大偶极子的证据。在非极性溶剂中，c3型有机凝胶，如DO3CH，形成超长的超分子聚合物，表现出显著的粘弹性。有人提出，DO3CH在非极性溶剂中的超分子结构由酰胺基团之间的3重氢键支撑的直柱组成1-5（图1）。DO3CH超分子结构的一个显著特征是存在由氢键固定方向引起的电宏偶极子。作为DO3CH中偶极子的和而产生的大的宏观偶极子也可以在蛋白质的r -螺旋柱中产生。最近，人们合成了许多有机凝胶，由于它们具有令人着迷的机械和结构特性，科学家们对它们产生了极大的兴趣。其中一种c3型有机凝胶，N, N ', N " -三（3,7 -二甲基辛基）苯- 1,3,5 -三羧基酰胺（DO3B），以苯基环为中心骨架代替环己烷，在非极性溶剂中形成长超分子聚合物，并且由于形成的超分子聚合物之间的缠结，其凝胶表现出显著的粘弹性。提出的DO3B的超分子结构由酰胺基团之间的3重氢键支撑的螺旋柱组成，而不是直柱（图1）。当DO3B不具有同手性(S)或(R)- 3,7 -二甲基辛基胺侧链，而是具有两种形式的外消旋混合物时，其超分子由左旋和右旋螺旋柱的等摩尔混合物组成。7-11在连续序列中连接左、右手柱的缺陷部分是由于未能形成氢键，这可能是超分子聚合物具有柔韧性的原因，并且可能在控制粘弹性的纠缠释放机制中起重要作用，可以用单个松弛时间来描述。11
Herein, we report evidence that highly controlled large macrodipoles are present in the supramolecular polymer of tri-3, 7-dimethyloctyl-cis-1, 3, 5-cyclohexanetricarboxamide (DO3CH) formed in n-decane (C10) due to 3-fold hydrogen bonds. In nonpolar solvents, C3-type organo-gelators such as DO3CH form enormously long supramolecular polymers that exhibit remarkable viscoelasticity. 1, 2 It has been proposed that the supramolecular structure of DO3CH in nonpolar solvents consists of a straight column sustained by 3-fold hydrogen bonds between amide groups1-5 (Figure 1). A striking characteristic of the supramolecular structure of DO3CH is the presence of electric macrodipoles resulting from the fixed direction of hydrogen bonds. Large macrodipoles created as the sum of dipoles in DO3CH may also be generated in columns such as R-helixes of proteins. 6 Recently, many organo-gelators have been synthesized, and they have generated great interest among scientists because of the fascinating mechanical and structural properties of their gels. One of the C3-type organo-gelators, N, N′, N′′-tris (3, 7-dimethyloctyl) benzene-1, 3, 5-tricarboxamide (DO3B), which has a phenyl ring as a central backbone instead of cyclohexane, forms long supramolecular polymers in nonpolar solvents, and its gels exhibit remarkable viscoelasticity due to entanglements between the formed supramolecular polymers. 1, 2, 5 The proposed supramolecular structure of DO3B consists of a helical column sustained by 3-fold hydrogen bonds between amide groups, rather than a straight column (Figure 1). When DO3B does not bear homochiral (S)-or (R)-3, 7-dimethyloctylamine side chains, but instead has a racemic mixture of the two forms, its supramolecules consist of an equimolar mixture of leftand right-handed helical columns. 7-11 Defective parts connecting left-and right-handed columns in a contiguous sequence result from failure to form hydrogen bonds, which may be the reason for the flexibility of the supramolecular polymer and may play an essential role in the entanglement release mechanism governing viscoelasticity that can be described with a single relaxation time. 11