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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
Local aromaticity in polycyclic aromatic hydrocarbons: electron delocalization versus magnetic indices
Patrick Bultinck1, Stijn Fias, Robert Ponec
1Ghent University, Department of Inorganic and Physical Chemistry, Krijgslaan 281 (S-3), 9000 Gent, Belgium. Patrick.Bultinck@UGent.be
Chemistry (Weinheim an Der Bergstrasse, Germany)
|September 5, 2006
Summary
This study investigates aromaticity in benzenoid rings using the Polansky index (P) and generalized population analysis (GPA). Findings correlate well with ring currents but not nucleus independent chemical shifts (NICS), highlighting the multidimensional nature of aromaticity.
Area of Science:
- * Computational Chemistry
- * Quantum Chemistry
- * Organic Chemistry
Background:
- * Aromaticity is a complex phenomenon crucial for understanding chemical stability and reactivity.
- * Various indices exist to quantify aromaticity, but their correlations can be inconsistent.
- * The multidimensional nature of aromaticity suggests different indices may capture distinct aspects.
Purpose of the Study:
- * To evaluate the local aromaticity of benzenoid rings using the Polansky index (P) and generalized population analysis (GPA).
- * To compare the results from P and GPA with other established aromaticity indices, including circuit-condensed ring currents and nucleus-independent chemical shifts (NICS).
- * To investigate the reasons behind observed correlations and discrepancies among different aromaticity measures.
Main Methods:
- * Calculation of the Polansky index (P) for local aromaticity.
- * Application of generalized population analysis (GPA) to assess electron distribution.
- * Comparison of P and GPA results with published data on ring currents and NICS values.
Main Results:
- * Strong agreement was found between the Polansky index (P), generalized population analysis (GPA), and circuit-condensed ring currents.
- * No significant correlation was observed between P/GPA and nucleus-independent chemical shifts (NICS).
- * The study identified that different aromaticity indices inherently measure distinct chemical phenomena, leading to varied correlations.
Conclusions:
- * The Polansky index (P) and generalized population analysis (GPA) are reliable indicators for local aromaticity in benzenoid systems.
- * Discrepancies with NICS underscore the complexity and multidimensionality of aromaticity.
- * Understanding the specific phenomena reflected by each index is crucial for accurate interpretation of aromaticity studies.
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