Related Experiment Video
Updated: May 1, 2026
08:18
Microscopic Visualization of Porous Nanographenes Synthesized through a Combination of Solution and On-Surface Chemistry
Published on: March 4, 2021
2.5K
Aromatic character of nanographene model compounds.
Kenkichi Sakamoto1, Naoko Nishina, Toshiaki Enoki
1Department of Chemistry, Faculty of Science, Shizuoka University , Oya, Shizuoka 422-8529, Japan.
The Journal of Physical Chemistry. A
|April 3, 2014
Summary
Superaromatic stabilization energy (SSE) quantifies local aromaticity in large carbon materials like polycyclic aromatic hydrocarbons (PAHs) and graphene nanoribbons. Edge structures dictate aromaticity patterns, influencing reactivity in these materials.
Area of Science:
- Materials Science
- Organic Chemistry
- Computational Chemistry
Background:
- Macrocyclic aromaticity is crucial for understanding carbon materials.
- Polycyclic Aromatic Hydrocarbons (PAHs) and graphene nanoribbons exhibit complex aromaticity.
Purpose of the Study:
- To introduce Superaromatic Stabilization Energy (SSE) as a local aromaticity index.
- To investigate the influence of edge structures on aromaticity patterns in large PAHs and graphene nanoribbons.
Main Methods:
- Definition and application of Superaromatic Stabilization Energy (SSE).
- Analysis of aromaticity patterns in model nanographene compounds.
Main Results:
- SSE effectively estimates local aromaticity in individual benzene rings.
- Edge structures, particularly armchair edges, dictate the placement of aromatic sextets.
- Aromaticity varies significantly near the edges of nanographene models.
Conclusions:
- Local aromaticity in large carbon systems is primarily governed by edge topology.
- SSE provides a valuable tool for assessing localized aromaticity and predicting reactivity in PAHs and graphene nanoribbons.
More Related Videos
Related Concept Videos
01:18Aromatic 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...
Due to the absence of continuous...
3.5K
01:13Five-Membered Heterocyclic Aromatic Compounds: Overview
4.4K
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,...
4.4K
01:14NMR 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
01:18Structure of Benzene: Molecular Orbital Model
11.4K
According to the molecular orbital (MO) model, benzene has a planar structure with a regular hexagon of six sp2 hybridized carbons. As shown in Figure 1, each carbon is bonded to three other atoms with C–C–C and H–C–C bond angles of 120°. The C–H bond length is 109 pm, and the C–C bond length is 139 pm which is midway between the single bond length of sp3 hybridized carbons (154 pm) and sp2 hybridized carbons (133 pm).
11.4K
01:20Criteria 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 Hückel’s rule or...
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...
10.6K
01:14π 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