groups takes a left-handed helicalconformation, while the polyamide β-DPA with (S)-β-methyl-substituted TEG groups takes a right-handed helicalconformation. The difference in the screw sense of α-DPA and β-DPA would be caused by the steric interaction between the main chain and the sidechain, as observed in poly(p-benzamide) possessing (S)-β-methyl-substituted TEG sidechains (β-PA) because the large
picture for the secondary structure of these polyamides in solution that the N-alkylated poly(p-benzamide)s possess a right-handed helicalconformation ((P)-helix). In the solid states, the results of X-ray crystallographic analysis of 4-(methylamino)benzoic acid oligomers substantiated that they have a helicalconformation with three monomer units per turn.
通过链增长缩聚方法合成在氮原子上带有手性侧链的聚(对苯甲酰胺)1。聚酰胺表现出明确的分子量和窄的多分散性。聚酰胺在几种有机溶剂 (CH(3)CN、CHCl(3) 和 CH(3)OH) 中的溶液显示出耦合振荡器的分散型 CD 信号特征,并且与相应的单体相比要大得多。就检测而言,CD 信号取决于聚酰胺的温度和分子量,但与溶剂无关。吸收和 CD 光谱的激子模型分析为这些聚酰胺在溶液中的二级结构提供了清晰的图片,即 N-烷基化聚(对苯甲酰胺)具有右手螺旋构象((P)-螺旋)。在固态下,
Molecular Structure of Helical Supramolecular Dendrimers
作者:Mihai Peterca、Virgil Percec、Mohammad R. Imam、Pawaret Leowanawat、Kentaro Morimitsu、Paul A. Heiney
DOI:10.1021/ja806524m
日期:2008.11.5
The molecular structure of helical supramolecular dendrimers generated from self-assembling dendrons and dendrimers and from self-organizable dendronized polymers was elucidated for the first time by the simulation of the X-ray diffraction patterns of their oriented fibers. These simulations were based on helical diffraction theory applied to simplified atomic helical models, followed by Cerius2 calculations
通过模拟定向纤维的 X 射线衍射图,首次阐明了由自组装树枝状聚合物和树枝状聚合物以及自组织树枝状聚合物产生的螺旋超分子树枝状聚合物的分子结构。这些模拟基于应用于简化原子螺旋模型的螺旋衍射理论,然后是基于其完整分子螺旋结构的 Cerius2 计算。筛选了数百个样品,直到包含 14 个超分子树枝状聚合物和树枝状聚合物的库在其定向纤维的 X 射线衍射图中提供了足够数量的螺旋特征。这种技术组合提供了单 9(2) 和 -11(3) 螺旋、三重 6(1)、-8(1)、-9(1) 和 -12(1) 螺旋的示例,以及由冠状树枝状大分子、空心和非空心超分子冠状树枝状大分子、空心和非空心超分子盘状树枝状大分子以及空心和非空心超分子和大分子螺旋状结构组装而成的八角 32(1) 螺旋。这里阐述的用于确定分子螺旋结构的方法是从结构生物学领域移植过来的,将适用于其他类别的合成螺旋组件。螺旋超分子组件的分子结构的确定有
Helical and Flat Structures from Chiral Dendronized Rectangular Oligo(phenylene ethynylene)s
The synthesis of two chiral amphiphiles and their self-assembling features in solution and onto surfaces is reported. The different degree of interdigitation of the paraffinic substituents has an enormous influence in the chirality of the aggregates. Thus, while oligo(phenyleneethynylene) 1 shows a bisignated Cotton effect in solution and P-type helices onto surfaces, compound 2 lacks in any dichroic
generally exist in cis conformation both in the crystalline state and in various solvents, and this cis conformational preference can be utilized to construct dynamic helical oligoamides. Here, we synthesized the pyrrole-containing amides 2–5 and their oligomers 6–8 and examined their conformations in the crystalline state and in solution. All the N-methylated amides showed cis conformational preference in