Related Experiment Video
Updated: Sep 27, 2026

Preparation of a Corannulene-functionalized Hexahelicene by Copper(I)-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units
Published on: September 18, 2016
The delocalization index as an electronic aromaticity criterion: application to a series of planar polycyclic
Jordi Poater1, Xavier Fradera, Miquel Duran
1Institut de Química Computacional, Departament de Química Universitat de Girona 17071 Girona, Catalonia, Spain.
Abstract:
This work introduces a new local aromaticity measure, defined as the mean of Bader's electron delocalization index (DI) of para-related carbon atoms in six-membered rings. This new electronic criterion of aromaticity is based on the fact that aromaticity is related to the cyclic delocalized distribution of pi-electrons. We have found that this DI and the harmonic oscillator model of aromaticity (HOMA) index are strongly correlated for a series of six-membered rings in eleven planar polycyclic aromatic hydrocarbons. The correlation between the DI and the nucleus-independent chemical shift (NICS) values is less remarkable, although in general six-membered rings with larger DI values also have more negative NICS indices. We have shown that this index can also be applied, with some modifications, to study of the aromaticity in five-membered rings.
More Related Videos
Related Concept Videos
Aromatic Hydrocarbon Anions: Structural Overview
Due to the absence of continuous overlap of p...
Aromatic Hydrocarbon Cations: Structural Overview
Removing one hydrogen from the intervening CH2 group with both...
Criteria for Aromaticity and the Hückel 4n + 2 Rule
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 the 4n + 2 rule.
IR Absorption Frequency: Delocalization
In IR spectroscopy,...
π Electron Effects on Chemical Shift: Aromatic and Antiaromatic Compounds
Frost Circles for Different Conjugated Systems

