在超分子二元和非线程超分子自组装之间切换stilbene amide-alpha-cyclodextrin通过光辐射
Kazuhiro Yamauchi1, Yoshinori Takashima, Akihito Hashidzume
1Department of Macromolecular Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
Journal of the American Chemical Society
|March 14, 2008
概括
光辐射可以控制超分子组件. 通过在水中进行跨至晶体的光异构化,3-trans-Stilbene amide-alpha-cyclodextrin (3-trans-Sti-alpha-CD) 二元体在水中转化为非线程结构.
科学领域:
- 超分子化学 超分子化学
- 摄影化学的使用.
- 材料科学是一种材料科学.
背景情况:
- 循环德克斯因其形成包容复合物的能力而闻名.
- 斯蒂尔衍生物可以经历光异构化,改变它们的几何形状和特性.
- 超分子组件为各种应用提供可调节的性能.
研究的目的:
- 在水溶液中研究3 - 转基胺-阿尔法-环氧德素 (3 - 转-Sti-阿尔法-CD) 的自我组装行为.
- 为了探索光异构化对3-trans-Sti-alpha-CD.CD的超分子结构的影响.
- 为了确定光照能否控制这些超分子复合物的结构转变.
主要方法:
- 合成的3 - 转基因stilbene胺基-α-cyclodextrin.in的合成.
- 进行光谱分析 (例如,NMR,UV-Vis) 来表征复合物.
- 光辐射实验以诱导异构化.
- 在水溶液中对所得到的超分子组件进行结构分析.
主要成果:
- 在水溶液中,3-trans-Sti-alpha-CD 形成双线二元体.
- 从trans到cis的stilbene部分的光异构化诱导了结构变化.
- 在光照辐射时,超分子结构从双线聚合物转变为无线聚合物.
- 观察到的结构变化可以通过光辐射控制.
结论:
- 在3-trans-Sti-alpha-CD复合体内的stilbene单元的光异构化是控制超分子结构的关键因素.
- 光辐射提供了一个可逆转换不同超分子结构的机制.
- 这些发现表明,基于循环德克斯林 - 斯蒂尔联体的光敏材料的潜力.
相关概念视频
Photochemical Electrocyclic Reactions: Stereochemistry
The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation
Selection Rules: Photochemical Activation
Diels–Alder Reaction Forming Cyclic Products: Stereochemistry
The Diels–Alder reaction is one of the robust methods for synthesizing unsaturated six-membered rings. The reaction involves a concerted cyclic movement of six π electrons: four π electrons from the diene and two π electrons from the dienophile.
Cycloaddition Reactions: MO Requirements for Photochemical Activation
Some cycloaddition reactions are activated by heat, while others are initiated by light. For example, a [2 + 2] cycloaddition between two ethylene molecules occurs only in the presence of light. It is photochemically allowed but thermally forbidden.
Diels–Alder Reaction Forming Bridged Bicyclic Products: Stereochemistry
Diels–Alder reactions between cyclic dienes locked in an s-cis configuration and dienophiles yield bridged bicyclic products.
[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
The Diels–Alder reaction is an example of a thermal pericyclic reaction between a conjugated diene and an alkene or alkyne, commonly referred to as a dienophile. The reaction involves a concerted movement of six π electrons, four from the diene and two from the dienophile, forming an unsaturated six-membered ring. As a result, these reactions are classified as [4+2] cycloadditions.
Thermal and Photochemical Electrocyclic Reactions: Overview
Electrocyclic reactions are reversible reactions. They involve an intramolecular cyclization or ring-opening of a conjugated polyene. Shown below are two examples of electrocyclic reactions. In the first reaction, the formation of the cyclic product is favored. In contrast, in the second reaction, ring-opening is favored due to the high ring strain associated with cyclobutene formation.


