通过修改H端Si(111) 表面,激活表面基基组
Peter Thissen1, Tatiana Peixoto, Roberto C Longo
1Department of Materials Science and Engineering, University of Texas at Dallas, 800 West Campbell Road, Richardson, Texas 75080, USA. peter.thissen@utdallas.edu
Journal of the American Chemical Society
|May 5, 2012
概括
用基组使表面功能化是电子学的关键. 新的无氧化表面在室温下对接种分子具有增强的反应性,提高了应用的稳定性.
科学领域:
- 表面化学 表面化学
- 材料科学 材料科学 材料科学
- 纳米技术纳米技术
背景情况:
- 半导体表面的化学功能化,特别是氧化,对于传感,光伏和催化等应用至关重要.
- 氧化物表面的基是主要的反应场所,但具有较低的反应性,使表面化等过程复杂化.
研究的目的:
- 与氧化相比,研究基在新型无氧化表面上的基活性.
- 为了证明酸分子在纳米模式的基终端表面上的室温化学接种.
- 为了阐明在水性环境中的无氧化上移植分子的增强稳定性.
主要方法:
- 开发一种新的无氧化表面,具有控制的纳米模式 (OH) 覆盖.
- 在室温下将酸分子化学接种到模型表面.
- 对氧化表面的表面反应性和稳定性的比较分析.
主要成果:
- 在无氧化表面的基团表现出明显高于氧化表面的基团的反应性.
- 在室温下成功移植了一层单酸酸分子.
- 与氧化物相比,移植的酸层在水环境中表现出优越的稳定性.
结论:
- 在无氧化上基的增强反应性和稳定性为表面功能化提供了更有效的途径.
- 这种基本的理解为改进的基于的传感器,光伏设备和纳米电子元件铺平了道路.
- 无氧化物表面的发展为先进材料的功能化提供了一个多功能平台.
相关概念视频
Radical Substitution: Hydrogenolysis of Alkyl Halides with Tributyltin Hydride
Radical substitution reactions can be used to remove functional groups from molecules. The hydrogenolysis of alkyl halides is one such reaction, where the weak Sn–H bond in tributyltin hydride reacts with alkyl halides to form alkanes. Here, the reagent Bu3SnH yields tributyltin halide as a byproduct.
The bonds formed in this reaction are stronger than the bonds broken, making it energetically favorable. The reaction follows a radical chain mechanism similar to radical halogenation reactions,...
The bonds formed in this reaction are stronger than the bonds broken, making it energetically favorable. The reaction follows a radical chain mechanism similar to radical halogenation reactions,...
Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide
Alkenes are converted to 1,2-diols or glycols through a process called dihydroxylation. It involves the addition of two hydroxyl groups across the double bond with two different stereochemical approaches, namely anti and syn. Dihydroxylation using osmium tetroxide progresses with syn stereochemistry.
Hydroboration-Oxidation of Alkenes
In addition to the oxymercuration–demercuration method, which converts the alkenes to alcohols with Markovnikov orientation, a complementary hydroboration-oxidation method yields the anti-Markovnikov product. The hydroboration reaction, discovered in 1959 by H.C. Brown, involves the addition of a B–H bond of borane to an alkene giving an organoborane intermediate. The oxidation of this intermediate with basic hydrogen peroxide forms an alcohol.
Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
Introduction
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
Acid Halides to Carboxylic Acids: Hydrolysis
Hydrolysis of acid halides is a nucleophilic acyl substitution reaction in which acid halides react with water to give carboxylic acids. The reaction occurs readily and does not require acid or a base catalyst.
As shown below, the mechanism involves a nucleophilic attack by water at the carbonyl carbon to form a tetrahedral intermediate. This is followed by the reformation of the carbon–oxygen π bond along with the departure of a halide ion. A final proton transfer step yields carboxylic acid...
As shown below, the mechanism involves a nucleophilic attack by water at the carbonyl carbon to form a tetrahedral intermediate. This is followed by the reformation of the carbon–oxygen π bond along with the departure of a halide ion. A final proton transfer step yields carboxylic acid...
Oxidation of Alkenes: Anti Dihydroxylation with Peroxy Acids
Diols are compounds with two hydroxyl groups. In addition to syn dihydroxylation, diols can also be synthesized through the process of anti dihydroxylation. The process involves treating an alkene with a peroxycarboxylic acid to form an epoxide. Epoxides are highly strained three-membered rings with oxygen and two carbons occupying the corners of an equilateral triangle. This step is followed by ring-opening of the epoxide in the presence of an aqueous acid to give a trans diol.


