富勒烯 - 碳烯 易斯酸添加物
Huaping Li1, Chad Risko, Jung Hwa Seo
1Center for Polymers and Organic Solids, Department of Chemistry & Biochemistry, University of California, Santa Barbara, California 93106, United States.
Journal of the American Chemical Society
|July 19, 2011
概括
研究人员发现,体积大的N-异环碳化合物 (NHC) 与C(60) 富勒烯反应,形成稳定的引物. 这种反应通过C-C键的形成有效地实现了富勒的n-doping,改变了它的电子性质.
科学领域:
- 富勒的化学结构
- 有机金属化学 有机金属化学
- 材料科学是一种材料科学.
背景情况:
- 富勒,如C 60),是具有独特电子性质的碳基.
- N-异环碳 (NHCs) 是多功能联体和有机基.
- 了解富勒烯兴奋剂对于开发先进电子材料至关重要.
研究的目的:
- 为了研究N-异环碳素 (NHCs) 和C(60) 富勒烯之间的反应.
- 为了描述由此产生的引证及其电子性质.
- 探索这种反应对富勒n-doping的潜力.
主要方法:
- 从NHC和C{60}中合成一个兹维特里 adduct.
- 紫外线-Vis光谱分析吸收带.
- 紫外光电谱 (UPS) 用于确定电离潜力.
- 密度函数理论 (DFT) 计算用于电子结构分析.
主要成果:
- 通过C-C单键形成一个热稳定的zwi-terionic adduct.
- 观察到的低能吸收带表明电子密度转移到C 60).
- 与原始C 60相比,Adduct的电离潜力明显较低 (∼1.5 eV).
- DFT的计算证实了C-C键内的电荷极化,电子密度转移到C(60) 中.
结论:
- 富勒可以作为易斯酸,与碳基的易斯基 (如NHCs) 反应.
- 反应的结果是通过C-C键形成的富勒烯核心的n-doping.
- 这项研究为调整 fullerene 电子特性提供了一条新的途径.
相关概念视频
02:33Lewis Acids and Bases
In 1923, G. N. Lewis proposed a generalized definition of acid-base behavior in which acids and bases are identified by their ability to accept or to donate a pair of electrons and form a coordinate covalent bond.
A coordinate covalent bond (or dative bond) occurs when one of the atoms in the bond provides both bonding electrons. For example, a coordinate covalent bond occurs when a water molecule combines with a hydrogen ion to form a hydronium ion. A coordinate covalent bond also results when...
A coordinate covalent bond (or dative bond) occurs when one of the atoms in the bond provides both bonding electrons. For example, a coordinate covalent bond occurs when a water molecule combines with a hydrogen ion to form a hydronium ion. A coordinate covalent bond also results when...
02:16Lewis Acids and Bases
This lesson delves into Lewis acids and bases in the context of the octet rule for electron-deficient compounds. Here, the concept is discussed, emphasizing the group 13 elements like boron or aluminium. Since group 13 elements possess three valence electrons, they form trivalent compounds with a sextet of electrons and a vacant orbital for the central atom. Consequently, these electron-deficient compounds accept electrons from other species to complete their octet in a chemical reaction. They...
02:42Acidity of 1-Alkynes
The acidic strength of hydrocarbons follows the order: Alkynes > Alkenes > Alkanes. The strength of an acid is commonly expressed in units of pKa — the lower the pKa, the stronger the acid. Among the hydrocarbons, terminal alkynes have lower pKa values and are, therefore, more acidic. For example, the pKa values for ethane, ethene, and acetylene are 51, 44, and 25, respectively, as shown here.
01:31Substituent Effects on Acidity of Carboxylic Acids
The acidity of carboxylic acids is influenced by the nature of the substituents bounded to the functional group. The acid strength is determined by the stability of the carboxylate anion—the conjugate base formed by dissociating the corresponding carboxylic acid.
01:09Conjugate Addition to α,β-Unsaturated Carbonyl Compounds
α,β-Unsaturated carbonyl compounds are molecules bearing a carbonyl and alkene functionality in conjugation with each other. The conjugation in the molecule leads to three resonance structures. The hybrid form exhibits two probable electrophilic sites: the carbonyl carbon and the β carbon.
01:27Conjugate Addition (1,4-Addition) vs Direct Addition (1,2-Addition)
α,β-Unsaturated carbonyl compounds with two electrophilic sites, the carbonyl carbon, and the β carbon, are susceptible to nucleophilic attack via two modes: conjugate or 1,4-addition and direct or 1,2-addition.
Conjugate addition results in a thermodynamically stable product. The reaction retains the stronger C=O bond at the expense of the weaker C=C π bond. The process is slow as the β carbon is less electrophilic than the carbonyl carbon.
Direct addition products are formed faster owing to...
Conjugate addition results in a thermodynamically stable product. The reaction retains the stronger C=O bond at the expense of the weaker C=C π bond. The process is slow as the β carbon is less electrophilic than the carbonyl carbon.
Direct addition products are formed faster owing to...