通过分散力克服极长的基碳-碳键的可变性
Peter R Schreiner1, Lesya V Chernish, Pavel A Gunchenko
1Institut für Organische Chemie der Justus-Liebig-Universität, Heinrich-Buff-Ring 58, D-35392 Giessen, Germany. prs@org.chemie.uni-giessen.de
Nature
|September 17, 2011
概括
研究人员通过合钻石体合成了具有创纪录的长碳-碳键的碳化合物. 由于具有吸引力的范德瓦尔斯力,这些分子表现出了显著的稳定性,挑战了化学中先前对固态效应的理解.
科学领域:
- 有机化学 有机化学
- 物理化学 物理化学
- 材料科学 材料科学 材料科学
背景情况:
- 绝缘效应,通常归因于排斥性保利力,在分子结构和反应性方面至关重要.
- 吸引力范德瓦尔斯力,包括伦敦分散力,对于完全理解化学结合是必不可少的.
- 之前的研究讨论了分支基的稳定性和通过固态拥挤创造长C-C键的可能性.
研究的目的:
- 合成和表征具有异常长碳-碳单键的碳化合物.
- 研究这些新碳化合物结构中的稳定性和潜在的吸引力.
- 探索固态相互作用和范德瓦尔斯力在分子稳定中的作用.
主要方法:
- 通过合纳米尺寸的刚性钻石状结构来合成基.
- 合成的碳化合物的特性,包括测量C-C键的长度.
- 密度函数理论 (DFT) 计算用于分析分子间相互作用和稳定性.
主要成果:
- 成功制备的碳化合物具有极长的C-C键,高达1.704 Å,是报告中最长的基.
- 合成的化合物表现出意想不到的热稳定性,分解发生在200°C以上.
- DFT计算显示,分子内-接触面之间的有吸引力的分散相互作用对稳定性有显著的贡献.
结论:
- 固态拥挤可以导致基中形成异常长的C-C键.
- 具有吸引力的范德瓦尔斯分散力在稳定具有长C-C键的固态阻碍分子方面发挥着至关重要的作用.
- 这些发现为在分子设计和稳定性中的固态效应和吸引力相互作用提供了新的见解.
相关概念视频
01:12Carbon Skeletons
Life on Earth is carbon-based, as all macromolecules that make up living organisms contain carbon atoms. All organic compounds have a carbon backbone. Each carbon atom is tetravalent and can bond with four other atoms, making it an extraordinarily flexible component of biological molecules. Because carbon’s valence electrons are stable, it rarely becomes an ion. As the carbon chain increases in length, structural modifications such as ring structures, double bonds, and branching side chains...
02:14Combustion Energy: A Measure of Stability in Alkanes and Cycloalkanes
The low reactivity in alkanes can be attributed to the non-polar nature of C–C and C–H σ bonds. Alkanes, therefore, were initially termed as “paraffins,” derived from the Latin words: parum, meaning “too little,” and affinis, meaning “affinity.”
Alkanes undergo combustion in the presence of excess oxygen and high-temperature conditions to give carbon dioxide and water. A combustion reaction is the energy source in natural gas, liquified petroleum gas (LPG), fuel oil, gasoline, diesel fuel, and...
Alkanes undergo combustion in the presence of excess oxygen and high-temperature conditions to give carbon dioxide and water. A combustion reaction is the energy source in natural gas, liquified petroleum gas (LPG), fuel oil, gasoline, diesel fuel, and...
01:28Stability of Conjugated Dienes
Introduction
A comparison of the enthalpies of hydrogenation of dienes reveals that conjugated dienes release less heat on hydrogenation, rendering them more stable than their nonconjugated analogs.
A comparison of the enthalpies of hydrogenation of dienes reveals that conjugated dienes release less heat on hydrogenation, rendering them more stable than their nonconjugated analogs.
01:04¹³C 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...
A broadband decoupling technique is used to simplify these complex, sometimes overlapping, signals. Broadband decoupling relies on a...
01:12Double Resonance Techniques: Overview
Double resonance techniques in Nuclear Magnetic Resonance (NMR) spectroscopy involve the simultaneous application of two different frequencies or radiofrequency pulses to manipulate and observe two distinct nuclear spins. One important application of double resonance is spin decoupling, which selectively suppresses coupling with one type of nucleus while observing the NMR signal from another nucleus, simplifying the spectrum and enhancing resolution.
Spin decoupling is usually achieved by...
Spin decoupling is usually achieved by...
01:28Carbon-dioxide Fixation
Carbon dioxide fixation in prokaryotes enables the assimilation of inorganic carbon into organic molecules, supporting biosynthetic pathways, sustaining ecosystems, and contributing to the global carbon cycle. It also has industrial applications in carbon capture and bioproduct synthesis. Autotrophic organisms rely on this process to utilize CO₂ as a carbon source in diverse environments.The Calvin CycleThe Calvin cycle is the most widespread carbon fixation mechanism, primarily used by...