相关实验视频

Updated: Apr 19, 2026

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

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

Published on: September 18, 2016

环法烯二离子中平面内芳香度:一个磁性圆形二极化和理论研究

Naoyuki Toriumi¹, Atsuya Muranaka, Eiichi Kayahara

¹Graduate School of Pharmaceutical Sciences, The University of Tokyo , 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.

Journal of the American Chemical Society

|December 20, 2014

概括

磁性循环二极化谱学揭示了 [8]cycloparaphenylene dications 和激素 cations 的电子结构. 这证实了 [8]cycloparaphenylene dications中的平面芳香度,解释了它们的稳定性.

科学领域:

有机化学有机化学
频谱学是一种光谱学.
计算化学的计算化学

背景情况:

环烯 ([n]CPPs) 是具有独特电子性质的迷人分子结构.
了解[n]CPP滴定和基滴定的电子结构和芳香性对于它们的应用至关重要.
之前对 [8]cycloparaphenylene ( [8]CPP) 种类的光谱带的分配是相互矛盾的.

研究的目的:

为了研究和澄清 [8]cycloparaphenylene dication ([8]CPP(2+)) 和基离子 ([8]CPP(•+)) 的电子结构.
解决 [8]CPP物种的紫外相对红外吸收光谱带的冲突分配.
为了探索[n]CPP的芳香性和稳定性dcation和dianions.

主要方法:

磁圆二极化 (MCD) 光谱法被用来研究电子转换.
进行分子轨道 (MO) 计算以分析电子结构.
使用核独立化学转移 (NICS) 分析来评估芳香度.

主要成果:

MCD光谱学为 [8]CPP(2+) 和 [8]CPP(•+) 的紫外相对红外吸收波段提供了明确的分配.
[8]CPP(2+) 由于 (4n + 2) π电子系统 (n = 7) 的原因,在平面内表现出芳香性.
理论计算表明[n]CPP二甲酸和二甲酸 (n = 5-10) 通常表现出平面内芳香度.

结论:

[8]CPP(2+) 的内平面芳香度是其显著稳定性的原因.
这些发现解决了光谱分配的模两可,并提供了对[n]CPP电子结构的更深入的理解.
在平面中的芳香度是[n]CPP dications和dianions在各种环形大小中的共同特征.

更多相关视频

Preparation of Stable Bicyclic Aziridinium Ions and Their Ring-Opening for the Synthesis of Azaheterocycles

Preparation of Stable Bicyclic Aziridinium Ions and Their Ring-Opening for the Synthesis of Azaheterocycles

Published on: August 22, 2018

Efficient Construction of Drug-like Bispirocyclic Scaffolds Via Organocatalytic Cycloadditions of α-Imino γ-Lactones and Alkylidene Pyrazolones

Efficient Construction of Drug-like Bispirocyclic Scaffolds Via Organocatalytic Cycloadditions of α-Imino γ-Lactones and Alkylidene Pyrazolones

Published on: February 7, 2019

相关概念视频

Aromatic Hydrocarbon Anions: Structural Overview

Aromatic Hydrocarbon Anions: Structural Overview

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...

Aromatic Hydrocarbon Cations: Structural Overview

Aromatic Hydrocarbon Cations: Structural Overview

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...

Criteria for Aromaticity and the Hückel 4n + 2 Rule

Criteria for Aromaticity and the Hückel 4n + 2 Rule

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 Hückel’s rule or...

Frost Circles for Different Conjugated Systems

Frost Circles for Different Conjugated Systems

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.

π Electron Effects on Chemical Shift: Aromatic and Antiaromatic Compounds

π Electron Effects on Chemical Shift: Aromatic and Antiaromatic Compounds

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...

Five-Membered Heterocyclic Aromatic Compounds: Overview

Five-Membered Heterocyclic Aromatic Compounds: Overview

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,...