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相关概念视频

Aromatic Hydrocarbon Anions: Structural Overview01:18

Aromatic Hydrocarbon Anions: Structural Overview

2.8K
Neutral hydrocarbons like cyclopentadiene with an odd number of carbon atoms and one intervening CH2 group in the ring are not aromatic. Cyclopentadiene with 4 π electrons does not satisfy the 4n + 2 π electron rule. Additionally, the intervening CH2 group is sp3 hybridized and lacks a vacant p orbital, thereby interrupting the overlap of p orbitals in a continuous manner and preventing the delocalization of π electrons throughout the ring.
Due to the absence of continuous...
2.8K
Aromatic Hydrocarbon Cations: Structural Overview01:18

Aromatic Hydrocarbon Cations: Structural Overview

2.8K
Cycloheptatriene is a neutral monocyclic unsaturated hydrocarbon that consists of an odd number of carbon atoms and an intervening sp3 carbon in the ring. The three double bonds in the ring correspond to 6 π electrons, which is a Huckel number, and therefore satisfies the criteria of 4n + 2 π electrons. However, the intervening sp3 carbon disrupts the continuous overlap of p orbitals. As a result, cycloheptatriene is not aromatic.
Removing one hydrogen from the intervening CH2 group...
2.8K
Frost Circles for Different Conjugated Systems01:18

Frost Circles for Different Conjugated Systems

2.7K
The inscribed polygon method is consistent with Hückel’s 4n + 2 rule and helps to learn whether the given cyclic compound is aromatic or not. The compound is stable and aromatic if every bonding molecular orbital (MO) is completely filled with a pair of electrons. However, if the non-bonding or antibonding orbitals are filled with electrons, the compound is unstable and not aromatic. Consider the Frost circle diagrams for cycloalkenes containing 4 to 8 carbons.
2.7K
Criteria for Aromaticity and the Hückel 4n + 2 Rule01:20

Criteria for Aromaticity and the Hückel 4n + 2 Rule

10.6K
Like benzene, cyclobutadiene and cyclooctatetraene are cyclic compounds with alternate single and double bonds. However, their chemical behavior differs from benzene, as they are unstable and not aromatic. So, what are the structural characteristics of unsaturated compounds categorized as aromatic?  
For the first time, Eric Hückel, a German chemical physicist, derived a set of structural features for a compound to be classified as aromatic. This is now known as...
10.6K
π Electron Effects on Chemical Shift: Aromatic and Antiaromatic Compounds01:14

π Electron Effects on Chemical Shift: Aromatic and Antiaromatic Compounds

1.2K
In aromatic compounds, such as benzene, the circulation of (4n + 2) π-electrons sets up a diamagnetic or diatropic ring current around the perimeter of the molecule. This current induces a magnetic field that opposes the external field inside the ring and reinforces it on the outside. The protons in benzene are deshielded and exhibit high chemical shifts in the range 6.5–8.5 ppm. The shielding effect at the center of the ring is evident in complex aromatic molecules, such as...
1.2K
Five-Membered Heterocyclic Aromatic Compounds: Overview01:13

Five-Membered Heterocyclic Aromatic Compounds: Overview

3.9K
Heterocyclic aromatic compounds are cyclic compounds that are aromatic and have one or more heteroatoms—atoms other than carbon, in the ring. Depending upon the number of atoms present in the ring, they can be either five or six-membered. Examples of five-membered heterocyclic aromatic compounds include pyrrole, furan, thiophene, and imidazole. Pyrrole consists of one nitrogen atom having one lone pair of electrons. Furan and thiophene have one oxygen and one sulfur heteroatom,...
3.9K

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相关实验视频

Updated: Jul 4, 2025

Preparation of a Corannulene-functionalized Hexahelicene by CopperI-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units
09:35

Preparation of a Corannulene-functionalized Hexahelicene by CopperI-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units

Published on: September 18, 2016

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调 (反) 芳香性:在 [8]-Circulene 框架上的变化.

Patrick W Fowler1, Cate S Anstöter2

  • 1Department of Chemistry, University of Sheffield, Sheffield, United Kingdom.

Chemphyschem : a European journal of chemical physics and physical chemistry
|January 27, 2024
PubMed
概括

这项研究使用ab initio ipsocentric方法模拟了 [8]-circulenes中的π电子移位能力. 框架的修改揭示了全方位的电子电流模式,有助于调整芳香度和反芳香度.

关键词:
在 ab initio 的计算中,反芳香性是一种反芳香性.芳香度是一种芳香度.电流密度的地图.它是以ipsocentric为中心的.

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Preparation of a Corannulene-functionalized Hexahelicene by CopperI-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units
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Preparation of a Corannulene-functionalized Hexahelicene by CopperI-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units

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Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
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科学领域:

  • * * 量子化学 是一个量子化学.
  • * 有机电子产品
  • * * 材料科学是一种材料科学.

背景情况:

  • *有机分子的光电子特性取决于π电子移位.
  • * π电子脱位性对通过异原子替代或氧化还原化学的电子数量变化敏感.
  • *诱导磁场电流诊断π电子脱位性和芳香性.

研究的目的:

  • * 基于四环环[def,jkl,pqr,vwx]四烯 (TCPTP) 的 [8]-环中模拟环流模式.
  • * 为了研究电荷状态,异质原子替代和碳-- (BN) 对替代对对π-delocalizability的影响.
  • * 解释当前的密度模式,使用二次中心的方法,并开发宏观周期框架的设计策略.

主要方法:

  • * 采用了ab initio阴位中心方法进行建模.
  • *使用的CHF/CTOCD-DZ2/6-31G**水平计算.
  • *分析诱导电流密度,根据对称性,能量和节点特征划分为轨道贡献.

主要成果:

  • * 在修改的TCPTP框架中建模了多种环流模式.
  • * 已证明能够获得全方位的当前可能性,从全球流通到本地化.
  • *确定了解释电流密度和指导分子设计的选择规则.

结论:

  • * 阴位中心法有效地模拟了复杂有机系统中的π电子脱位.
  • *对TCPTP框架的修改允许微调芳香和反芳香性质.
  • *获得的洞察力可以为设计具有定制光电子特性的新型宏循环材料提供信息.