通过电化学还原二末端组来控制单分子结的形成
Thomas Hines1, Ismael Díez-Pérez, Hisao Nakamura
1Center for Biosensors and Bioelectronics, The Biodesign Institute, and School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, Arizona 85287, United States.
Journal of the American Chemical Society
|February 15, 2013
概括
研究人员使用电化学控制了单分子结节的形成,以创建强大的黄金-碳键. 与传统的氨基键相比,这种方法提高了分子结的稳定性和形成产量.
科学领域:
- 分子电子学分子电子学
- 电化学 电化学 电化学
- 材料科学是一种材料科学.
背景情况:
- 单分子结点对于分子电子学至关重要.
- 传统的结节形成通常依赖于氨基基,这可能会限制稳定性.
- 在单个分子水平上控制键形成是一个关键的挑战.
研究的目的:
- 开发一种新的方法来形成具有更高稳定性和产量的单分子结.
- 研究用于直接金属分子结合的二终端组的电化学还原.
- 为了比较通过直接共价键与氨基键形成的分子-金结的稳定性.
主要方法:
- 在一个分子上电化学减小轴性二氧化末端组.
- 在分子和黄金电极之间直接形成黄金-碳 (Au-C) 共价键.
- 步骤长度分析以评估接口稳定性和拉力距离.
- 计算Au-C和金- (Au-N) 债券的结合能.
主要成果:
- 通过电化学还原,成功控制了单分子连接的形成.
- 当电极电位接近二氧化还原电位时,分子连接形成的产量得到了增强.
- 与直接Au-C债券形成的连接显示出明显更大的稳定性和更长的拉距离,而不是与氨基债券形成的连接.
- 对Au-C键的计算较低的结合能解释了观察到的增强稳定性.
结论:
- 电化学还原二氧化组提供了一种强大的方法,用于创建稳定的单分子结.
- 直接的Au-C共价键在分子连接处提供了比传统的Au-N键更高的稳定性.
- 这种方法有望推动分子电子和纳米尺度设备制造领域的发展.
相关概念视频
Diazonium Group Substitution: –OH and –H
Nitrous acid, a weak acid, is prepared in situ via the reaction of sodium nitrite with a strong acid under cold conditions. This nitrous acid prepared in situ reacts with primary arylamines to form arenediazonium salts. Such reactions are known as diazotization reactions. As shown in Figure 1, the formation of arenediazonium salts begins with the decomposition of nitrous acid in an acidic solution to give nitrosonium ions.
1° Amines to Diazonium or Aryldiazonium Salts: Diazotization with NaNO2 Mechanism
Nitrous acid is a relatively weak and unstable acid prepared in situ by the reaction of sodium nitrite and cold, dilute hydrochloric acid. In an acidic solution, the nitrous acid undergoes protonation when it loses water to form a nitrosonium ion—an electrophile. Nitrous acid reacts with primary amines to give diazonium salts. The reaction is called diazotization of primary amines.
Aryldiazonium Salts to Azo Dyes: Diazo Coupling
The reaction of weakly electrophilic aryldiazonium (also called arenediazonium) salts with highly activated aromatic compounds leads to the formation of products with an —N=N— link, called an azo linkage. This reaction, presented in Figure 1, is known as diazo coupling and occurs without the loss of the nitrogen atoms of the aryldiazonium salt. Highly activated aromatic compounds such as phenols or arylamines favor the diazo coupling reaction. The coupling generally occurs at the para position.
Diazonium Group Substitution with Halogens and Cyanide: Sandmeyer and Schiemann Reactions
Arenediazonium substitution reactions occur when the diazonium group is substituted by various functional groups such as halides, hydroxyl, nitrile, etc. For instance, arenediazonium salts react with copper(I) salts of chloride, bromide, or cyanide to form corresponding aryl chlorides, bromides, and nitriles. These reactions are named Sandmeyer reactions. Although the mechanism of this reaction is complicated, as illustrated in Figure 1, they are believed to progress via an aryl copper...


