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相关概念视频

Carbon-13 (¹³C) NMR: Overview01:10

Carbon-13 (¹³C) NMR: Overview

Carbon-13 is a naturally occurring NMR-active isotope of carbon with a low natural abundance of 1.1%. In contrast, carbon-12 is the most abundant isotope of carbon with zero nuclear spin. Therefore, it is NMR inactive. The gyromagnetic ratio of carbon-13 is smaller than that of protons. As a result, carbon-13 resonance is about 6000 times weaker than proton resonance. For a given magnetic field strength, the resonance frequency of carbon-13 is about one-fourth of the resonance frequency for...
¹³C NMR: Distortionless Enhancement by Polarization Transfer (DEPT)01:20

¹³C NMR: Distortionless Enhancement by Polarization Transfer (DEPT)

When proton-coupled carbon-13 spectra are simplified by a broadband proton decoupling technique, structural information about the coupled protons is lost. Distortionless enhancement by polarization transfer (DEPT) is a technique that provides information on the number of hydrogens attached to each carbon in a molecule. While the DEPT experiment utilizes complex pulse sequences, the pulse delay and flip angle are specifically manipulated. The resulting signals have different phases depending on...
2D NMR: Heteronuclear Single-Quantum Correlation Spectroscopy (HSQC)01:19

2D NMR: Heteronuclear Single-Quantum Correlation Spectroscopy (HSQC)

Heteronuclear single-quantum correlation spectroscopy (HSQC) is a 2D NMR technique that reveals one-bond correlations between hydrogen and a heteronucleus. The HSQC experiment is similar to the heteronuclear correlation experiment (HETCOR) but is more sensitive. In the HSQC spectrum, the proton chemical shift is plotted on the horizontal F2 axis, while the 13C chemical shift is plotted on the vertical F1 axis. The corresponding proton and 13C spectra are also shown. The HSQC contour plot does...
Radicals: Electronic Structure and Geometry01:07

Radicals: Electronic Structure and Geometry

This lesson delves into the geometry of a radical, which is influenced by the electronic structure of the molecule. The principle is similar to that of a lone pair, where the unpaired electron influences the geometry at the radical center.
Accordingly, the structure of a trivalent radical lies between the geometries of carbocations and carbanions. An sp2-hybridized carbocation is trigonal planar, while an sp3-hybridized carbanion is trigonal pyramidal. Here, the difference in geometry is...
¹H NMR Chemical Shift Equivalence: Homotopic and Heterotopic Protons01:03

¹H NMR Chemical Shift Equivalence: Homotopic and Heterotopic Protons

Protons in identical electronic environments within a molecule are chemically equivalent and have the same chemical shift. The replacement test is a useful tool to identify chemical equivalence and predict NMR spectra. A substituent replaces each of the protons being examined and the resulting molecules are compared. If the same molecule is obtained, the protons are equivalent or homotopic. Replacement of any hydrogens in ethane by chlorine yields chloroethane because all six protons are...
¹³C NMR: ¹H–¹³C Decoupling01:04

¹³C NMR: ¹H–¹³C Decoupling

The probability of having two carbon-13 atoms next to each other is negligible because of the low natural abundance of carbon-13. Consequently, peak splitting due to carbon-carbon spin-spin coupling is not observed in spectra. However, protons up to three sigma bonds away split the carbon signal according to the n+1 rule, resulting in complicated spectra.
A broadband decoupling technique is used to simplify these complex, sometimes overlapping, signals. Broadband decoupling relies on a...

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相关实验视频

Updated: Jul 10, 2026

Preparation of a Corannulene-functionalized Hexahelicene by Copper(I)-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units
09:35

Preparation of a Corannulene-functionalized Hexahelicene by Copper(I)-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units

Published on: September 18, 2016

不溶性小HOMO-LUMO-gap空洞高烯的三甲基衍生物. 在C2-(C74-D3h) ((CF3) 12的NMR和DFT结构阐明中,Cs-(C76-Td) (2)) ((CF3) 12的Cs- ((C78-D3h)) (5))

Natalia B Shustova1, Igor V Kuvychko, Robert D Bolskar

  • 1Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA.

Journal of the American Chemical Society
|December 7, 2006
PubMed
概括

研究人员合成了新的三甲基烯,包括空心C74-D3h和以前未发现的C76,C78,C80和C82同位素. 这些发现扩大了对富勒化学及其潜在应用的理解.

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Last Updated: Jul 10, 2026

Preparation of a Corannulene-functionalized Hexahelicene by Copper(I)-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units
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Preparation of a Corannulene-functionalized Hexahelicene by Copper(I)-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units

Published on: September 18, 2016

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Standardized Identification of Compound Structure in Tibetan Medicine Using Ion Trap Mass Spectrometry and Multiple-Stage Fragmentation Analysis
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科学领域:

  • 超分子化学 超分子化学
  • 材料科学 材料科学 材料科学
  • 有机化学 有机化学

背景情况:

  • 富勒烯是碳的异构体,具有独特的形结构.
  • 富勒的功能化,如三甲基,可以改变它们的特性.
  • 高级富勒伦及其衍生物的合成和表征仍然具有挑战性.

研究的目的:

  • 研究较高富勒与三甲基化物 (CF3I) 的反应.
  • 为了分离和描述新型的三甲基化烯化合物.
  • 为了确定这些新的烯衍生物的结构.

主要方法:

  • 不溶性较高富勒与CF3I.I的高温反应.
  • 合成的富勒烯化合物的隔离和净化.
  • 使用19F核磁共振 (NMR) 光谱和密度功能理论 (DFT) 计算进行结构阐明.

主要成果:

  • 合成了C74(CF3) 12,C76(CF3) 12,C78(CF3) 12,C80(CF3) 12,C82(CF3) 12和C84(CF3) 12的合成方法.
  • 确定七种分离化合物中的六种最可能的结构,其中包括具有特定异构体的边缘共享的para-C6 (((CF3) 2六边形,形成带和/或循环.
  • 识别了具有空心C74-D3h的第二个可分离化合物,以及在弧度放电烟尘中发现空心富勒伦C76-Td(2),C78-D3h(5),C80-C2v(5) 和C82-C2(5) 的第一个实验证据.

结论:

  • 反应条件成功地产生了多种三甲基化高富勒.
  • 该研究为几种新的富勒烯衍生物提供了明确的结构赋值.
  • 这项工作提供了第一个实验证据,证明了特定的空心烯结构的存在,扩大了已知的烯家族.