从动力转化为热力学控制的复杂螺旋柱的自组织,这些复杂的螺旋柱具有3D周期性,由树化烯双化物组装而成
Virgil Percec1, Hao-Jan Sun, Pawaret Leowanawat
1Roy & Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA. percec@sas.upenn.edu
Journal of the American Chemical Society
|February 15, 2013
概括
凝聚性二烯基胺 (PBI) 分子自组装成螺旋柱. 观察到在不同温度和加热速度下发生的结构转变,揭示了先进材料设计的新阶段行为.
科学领域:
- 超分子化学 超分子化学
- 材料科学 材料科学 材料科学
- 有机化学 有机化学
背景情况:
- 丹德罗化烯3,4:9,10-四碳酸双化物 (PBI) 自组装成复杂的螺旋柱.
- 之前的研究发现了2(1) 螺旋式重复,具有特定的内部和间隔距离.
- 热力学和动力学控制影响2D六边形和3D单临床柱状相的形成.
研究的目的:
- 合成和结构分析一个 (3,4,5) nG1-m-PBI化合物的库 (n=12到6,m=1).
- 为了研究温度和加热/冷却速度对这些斑块化PBIs的自组装行为的影响.
- 了解这些复杂分子中的相变和结构秩序.
主要方法:
- 合成了一种经经经变形的PBI衍生品库.
- 差分扫描热量计 (DSC) 用于热分析.
- 在粉末和定向纤维上进行X射线衍射 (XRD).
- 固态核磁共振 (NMR) 光谱学. 固态核磁共振 (NMR) 光谱学.
- 分析温度和加热/冷却速度对结构的影响.
主要成果:
- 合成和分析了一个 (3,4,5) nG1-m-PBI化合物的库.
- 准备好的样本 (n=12到10) 在低温下显示出3D分层阵列,在加热/冷却时不可逆转地转化为柱状结构.
- 在n=12 PBI的动力控制的3D柱状相变为n=10到6的热力学控制.
结论:
- 随着树突大小 (n) 的变化,观察到自我组装行为的前所未有的转变.
- 这项研究揭示了从动力控制转向热力学控制的柱状相随着树突大小的减少.
- 这些发现对于设计基于dendronized PBI和类似的自组装系统的功能材料至关重要.
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