在可逆磁体形成和交换过程中合并宪法和运动共价动态
Petr Kovaříček1, Jean-Marie Lehn
1Laboratoire de Chimie Supramoléculaire, Institut de Science et d'Ingénierie Supramoléculaires, Université de Strasbourg, France.
Journal of the American Chemical Society
|May 16, 2012
概括
动态共价化学在近距离研究方面取得了进展. 这些分子表现出独特的内部和分子间交换过程,使得可以控制分子运动,并为新型分子装置铺平了道路.
科学领域:
- 有机化学 有机化学
- 超分子化学 超分子化学
- 材料科学 材料科学 材料科学
背景情况:
- 动态共价化学 (DCvC) 使用可逆共价键来创建可适应的分子系统.
- 从和胺中形成的胺是DCvC中关键的功能组.
- 了解 imine 动力学对于设计响应性材料和分子机器至关重要.
研究的目的:
- 研究各种磁体的形成和交换过程.
- 探索伊米因在动态共价化学和分子运动中的潜力.
- 为了描述不同分子架构中的 imines 的运动行为.
主要方法:
- 合成和表征由甲,二甲和甲衍生而来的伊米因.
- 质子核磁共振 (NMR) 光谱,包括1D,2D和交换光谱 (EXSY) 技术.
- 分析与异形二胺和多胺形成的单胺中内部和分子间的交换过程.
主要成果:
- 甲衍生的 imines 呈现出高效率和快速的速度,适合DCvC.
- 含有二胺的单胺体表现出自我转化,导致局部运动,如"步入位"或"单步".
- 胺基的运动可以通过替代剂,溶剂和温度来控制,而化物残留物沿着聚胺链移动.
结论:
- 伊米因是表现出相对分子部分运动的系统的原型,与分子电机相关.
- 观察到的动态共价运动将DCvC扩展到分子动力学领域,而不会改变分子构成.
- 这些发现为先进的分子设备设计具有联合运动和构成动态行为的多功能分子开辟了道路.
相关概念视频
01:23Aldehydes and Ketones with Amines: Imine Formation Mechanism
Imine formation involves the addition of carbonyl compounds to a primary amine. It begins with the generation of carbinolamine through a series of steps involving an initial nucleophilic attack and then several proton transfer reactions. The second part includes the elimination of water, as a leaving group, to give the imine.
Imines are formed under mildly acidic conditions. A pH of 4.5 is ideal for the reaction.
If the pH is low or the solution is too acidic, the reaction slows down in the...
Imines are formed under mildly acidic conditions. A pH of 4.5 is ideal for the reaction.
If the pH is low or the solution is too acidic, the reaction slows down in the...
01:16Aldehydes and Ketones with Amines: Imine and Enamine Formation Overview
Primary amines react with carbonyl compounds—aldehydes and ketones—to generate imines. Imines consist of a C=N double bond and are named Schiff bases after its discoverer—the German chemist Hugo Schiff. On the other hand, secondary amines react with carbonyl compounds to give enamines. In enamines, the presence of a C=C double bond adjacent to the nitrogen atom leads to the delocalization of the lone pair.
01:14Aldehydes and Ketones with Amines: Enamine Formation Mechanism
Enamine formation involves the addition of carbonyl compounds to a secondary amine through a series of reactions. The mechanism begins with the generation of carbinolamine, a nucleophilic attack followed by several proton transfer reactions. The hydroxyl group of the carbinolamine is converted into water to make a better leaving group that can push the reaction forward by eliminating a water molecule. In enamine formation, the last step involves the abstraction of a proton from the α carbon to...
01:16Cycloaddition Reactions: MO Requirements for Thermal Activation
Thermal cycloadditions are reactions where the source of activation energy needed to initiate the reaction is provided in the form of heat. A typical example of a thermally-allowed cycloaddition is the Diels–Alder reaction, which is a [4 + 2] cycloaddition. In contrast, a [2 + 2] cycloaddition is thermally forbidden.
01:26Preparation of 1° Amines: Hofmann and Curtius Rearrangement Mechanism
The Hofmann and Curtius rearrangement reactions can be applied to synthesize primary amines from carboxylic acid derivatives such as amides and acyl azides. In the Hofmann rearrangement, a primary amide undergoes deprotonation in the presence of a base, followed by halogenation to generate an N-haloamide. A second proton abstraction produces a stabilized anionic species, which rearranges to an isocyanate intermediate via an alkyl group migration from the carbonyl carbon to the neighboring...
01:08Types of Chemical Reactions: Exchange and Reversible
An exchange reaction is a chemical reaction in which both synthesis and decomposition occur, chemical bonds are both formed and broken, and chemical energy is absorbed, stored, and released.
A special kind of exchange reaction is the oxidation-reduction reaction, or the redox reaction. These reactions involve the transfer of electrons from one compound to another. The electrons in these reactions commonly come from hydrogen atoms, which consist of an electron and a proton. A molecule gives up a...
A special kind of exchange reaction is the oxidation-reduction reaction, or the redox reaction. These reactions involve the transfer of electrons from one compound to another. The electrons in these reactions commonly come from hydrogen atoms, which consist of an electron and a proton. A molecule gives up a...