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Published on: August 19, 2013
The aromatic fluctuation index (FLU): a new aromaticity index based on electron delocalization
Eduard Matito1, Miquel Duran, Miquel Solà
1Institut de Química Computacional and Departament de Química, Universitat de Girona, 17071 Girona, Catalonia, Spain.
The Journal of Chemical Physics
|January 11, 2005
Summary
A new measure called aromatic fluctuation index (FLU) quantifies aromaticity by examining electron charge fluctuations between atoms in a ring. This index correlates well with existing methods and offers broader applicability for assessing molecular aromatic character.
Area of Science:
- Quantum Chemistry
- Computational Chemistry
- Organic Chemistry
Background:
- Aromaticity is a key concept in chemistry, crucial for understanding molecular stability and reactivity.
- Existing aromaticity measures often have limitations in scope or applicability.
- Understanding electron delocalization is fundamental to defining aromaticity.
Purpose of the Study:
- Introduce a novel electronic criterion for measuring aromaticity: the aromatic fluctuation index (FLU).
- Develop a new method to quantify the fluctuation of electronic charge between adjacent atoms within a ring system.
- Provide a versatile tool for analyzing both local and global aromaticity in molecules.
Main Methods:
- Defined the aromatic fluctuation index (FLU) based on electron sharing and similarity between adjacent atoms in a ring.
- Applied FLU to analyze rings within 15 planar polycyclic aromatic hydrocarbons.
- Compared FLU with established aromaticity indicators like the harmonic-oscillator model of aromaticity, nucleus-independent chemical shift, and para-delocalization index (PDI).
Main Results:
- The aromatic fluctuation index (FLU) demonstrated a strong correlation with other widely used local aromaticity indicators.
- FLU successfully captures the cyclic delocalization of pi electrons, a hallmark of aromaticity.
- Unlike PDI, FLU is applicable to rings of any size.
Conclusions:
- The aromatic fluctuation index (FLU) is a robust and broadly applicable new measure of aromaticity.
- FLU provides valuable insights into both local and global aromatic character.
- This index offers a promising alternative for aromaticity assessment in diverse chemical systems.
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