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Published on: September 18, 2016
Aromatic expanded isophlorins: stable 30pi annulene analogues with diverse structural features
J Sreedhar Reddy1, Venkataramanarao G Anand
1Chemical Sciences & Technology Division, National Institute for Interdisciplinary Science and Technology, Trivandrum 695019, India.
Journal of the American Chemical Society
|November 19, 2009
Summary
Novel aromatic expanded isophlorins, higher analogues of 20pi isophlorin, were synthesized. These 30pi systems exhibit aromaticity and unique ring-inverted structures, confirmed by NMR and X-ray diffraction.
Area of Science:
- Organic Chemistry
- Macromolecular Chemistry
- Aromaticity Studies
Background:
- Isophlorins are macrocyclic compounds with conjugated pi systems.
- Higher analogues of isophlorins, termed expanded isophlorins, are of significant interest.
- Annulenes are idealized aromatic systems; their higher analogues are largely unrealized.
Purpose of the Study:
- To synthesize novel aromatic expanded isophlorins.
- To investigate the structural diversity and aromatic properties of these compounds.
- To explore their optical properties and conformational behavior.
Main Methods:
- Synthesis from readily available precursors.
- Characterization using 1H NMR spectroscopy.
- Structural determination via single-crystal X-ray diffraction analysis.
Main Results:
- Successful synthesis of aromatic expanded isophlorins (30pi systems).
- Demonstration of ring-inverted structures influenced by heteroatoms.
- Confirmation of (4n + 2)pi aromaticity through spectroscopic and crystallographic data.
- Observation of strong intermolecular C(sp2)-H...F-C(sp2) hydrogen bonds.
Conclusions:
- Expanded isophlorins represent a new class of aromatic macrocycles.
- Their unique structures and properties offer insights into aromaticity in complex systems.
- These findings contribute to the understanding of annulene analogues and macrocyclic chemistry.
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