What is aromaticity?

Abstract

Abstract

On the Harmonic Oscillator Model of Electron Delocalization (HOMED) Index and its Application to Heteroatomic π-Electron Systems

“…hyperconjugation, conjugation, aromaticity, tautomerism, proton-transfer, and/or hydrogen bonding, may take place [10,11,[36][37][38][39][40]. We analyzed π-electron delocalization for simple σ-π hyperconjugated, n-π conjugated, π -π conjugated, and aromatic compounds including those displaying prototropic tautomerism.…”

Efficient mapping of ring currents in fullerenes and other curved carbon networks

“…A widely accepted criterion of aromaticity for a cyclic system is its ability to sustain a diatropic ring current induced by the presence of a perpendicular external magnetic field [10][11][12][13][14][15][16]. Such currents can be inferred indirectly from their effects on observable magnetic properties (exaltation of magnetisability [17][18][19], downfield chemical shifts of external hydrogen nuclei [20]) and properties that are sub-observables, in Hirschfelder's sense [21], such as the characteristically negative NICS value at the ring centre or some other chosen point [22].…”

Development and Evaluation of a QSPR Model for the Prediction of Diamagnetic Susceptibility

“…The introduction of groups with high diameter (Diam) is recommended to increase the diamagnetic susceptibility and hence the aromaticity of the module [10]. In contrast, the presence of atoms of oxygen, nitrogen, sulfur, and the atoms of hydrogen bonded to any of these atoms increases the PSAr value and should be avoided.…”

“…In those studies an extensive bibliographical research was made and the references herein are omitted for brevity. Diamagnetic susceptibility (c m ) is the only measurable property, which is uniquely associated with aromaticity since compounds which exhibit significantly exalted diamagnetic susceptibility are aromatic [10]. An attempt to apply QSPR models for the quantification of aromaticity was made by Duchowicz and Castro [11].…”