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関連する概念動画

π Electron Effects on Chemical Shift: Aromatic and Antiaromatic Compounds01:14

π Electron Effects on Chemical Shift: Aromatic and Antiaromatic Compounds

1.7K
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...
1.7K
Aromatic Hydrocarbon Anions: Structural Overview01:18

Aromatic Hydrocarbon Anions: Structural Overview

3.5K
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...
3.5K
Basicity of Aromatic Amines01:18

Basicity of Aromatic Amines

7.7K
The basicity of aromatic amines is much weaker than that of aliphatic amines due to the involvement of the lone pair of electrons over the N atom in resonance with the aryl rings. Generally, the electron-donating ability of any substituents on the aryl ring of aromatic amines increases the basicity of the amine by increasing electron density, and hence the availability of lone pair on the nitrogen. On the other hand, electron-withdrawing functional groups on the aryl ring of amines decrease the...
7.7K
NMR Spectroscopy of Aromatic Compounds01:14

NMR Spectroscopy of Aromatic Compounds

4.7K
Aromatic compounds can be identified or analyzed using proton NMR and carbon‐13 NMR. Typically, aromatic hydrogens or hydrogens directly bonded to the aromatic rings are strongly deshielded by the aromatic ring current. Therefore, they absorb in the range of 6.5–8.0 ppm in proton NMR spectra. For instance, aromatic hydrogens directly bonded to the benzene ring absorb at 7.3 ppm. However, aromatic hydrogens of larger rings absorb farther upfield or downfield than the ideal range.
4.7K
Spin–Spin Coupling: One-Bond Coupling01:17

Spin–Spin Coupling: One-Bond Coupling

1.2K
Coupling interactions are strongest between NMR-active nuclei bonded to each other, where spin information can be transmitted directly through the pair of bonding electrons. While nuclei polarize their electrons to the opposite spins, the bonding electron pair has opposite spins. Configurations with antiparallel nuclear spins are expected to be lower in energy. When coupling makes antiparallel states more favorable, J is considered to have a positive value. The one-bond coupling constant, 1J,...
1.2K
Frost Circles for Different Conjugated Systems01:18

Frost Circles for Different Conjugated Systems

3.3K
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.
3.3K

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関連する実験動画

Updated: May 4, 2026

Orientational Transition in a Liquid Crystal Triggered by the Thermodynamic Growth of Interfacial Wetting Sheets
06:26

Orientational Transition in a Liquid Crystal Triggered by the Thermodynamic Growth of Interfacial Wetting Sheets

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アロマティック性は単一分子交差点の伝導性を低下させる.

Wenbo Chen1, Haixing Li, Jonathan R Widawsky

  • 1Department of Chemistry, Columbia University , New York, New York 10027, United States.

Journal of the American Chemical Society
|January 9, 2014
PubMed
まとめ

分子ワイヤの伝導性は,五つ組のリングの芳香度が増加するにつれて減少します. 非芳香性サイクロペンタディエンのワイヤは,芳香性フランとチオフェンのワイヤよりも高い電気伝導性を示します.

科学分野:

  • 分子電子は分子電子である.
  • オーガニック・ケミストリー オーガニック・ケミストリー
  • 凝縮物質物理学 凝縮物質物理学

背景:

  • 単分子電子は,電荷輸送の正確な制御を提供します.
  • 分子ワイヤの構造-特性関係を理解することは,デバイス設計において極めて重要です.

研究 の 目的:

  • 分子ワイヤの周期的な五連鎖の環の芳香度とその電気伝導度との関係を調査する.
  • 分子構造が単一分子レベルで電荷輸送にどのように影響するかを決定する.

主な方法:

  • スキャニング・トンネリング・顕微鏡ベースのブレイク・ジャンクション・テクニックを用いて,単一分子・ジャンクションを形成し,測定する.
  • サイクロペンタディエン,フラン,チオフェン環を組み込んだ分子ワイヤを合成し,試験する.

主要な成果:

  • シングル分子伝導性は,サイクロペンタディエン,フラン,チオフェンを含むワイヤーを測定しました.
  • 5つの環の共振エネルギー (芳香度) と測定された伝導率の間に負の相関が観察されました.
  • 非芳香性サイクロペンタディエン誘導体は,芳香性フランおよびチオフェン誘導体よりも高い伝導性を示した.
  • フラン基のワイヤの伝導性は,同類のチオフェン系よりも一貫して高く,観測された傾向の強さを確認しました.

さらに関連する動画

Effect of Bending on the Electrical Characteristics of Flexible Organic Single Crystal-based Field-effect Transistors
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Single-Molecule Förster Resonance Energy Transfer Methods for Real-Time Investigation of the Holliday Junction Resolution by GEN1
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関連する実験動画

Last Updated: May 4, 2026

Orientational Transition in a Liquid Crystal Triggered by the Thermodynamic Growth of Interfacial Wetting Sheets
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Orientational Transition in a Liquid Crystal Triggered by the Thermodynamic Growth of Interfacial Wetting Sheets

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Effect of Bending on the Electrical Characteristics of Flexible Organic Single Crystal-based Field-effect Transistors
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Single-Molecule Förster Resonance Energy Transfer Methods for Real-Time Investigation of the Holliday Junction Resolution by GEN1
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結論:

  • 分子幹の芳香性は単一分子伝導性に大きく影響する.
  • 低芳香度,特にキノイド型を好む構造は,より高い伝導率につながります.
  • 発見は,分子設計戦略は,分子ワイヤの伝導性を高めるために芳香的安定化を最小限にすることを考慮すべきことを示唆しています.