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Azulichlorins and Benzocarbachlorins Derived Therefrom
Mario A Noboa1, Deyaa I AbuSalim1, Timothy D Lash1
1Department of Chemistry , Illinois State University , Normal , Illinois 61790-4160 , United States.
The Journal of Organic Chemistry
|August 21, 2019
Summary
Researchers synthesized novel azulichlorins and benzocarbachlorins, revealing unique aromaticity and electronic delocalization pathways. These macrocycles exhibit distinct spectral properties and stability depending on protonation state, offering insights into complex organic structures.
Area of Science:
- Organic Chemistry
- Supramolecular Chemistry
- Spectroscopy
Background:
- Macrocyclic compounds are crucial in various chemical applications.
- Azulipyrranes and dipyrrins are known building blocks for complex organic molecules.
- Understanding aromaticity and electronic properties in novel macrocycles is key to developing new materials.
Purpose of the Study:
- To synthesize and characterize the first examples of azulichlorins and benzocarbachlorins.
- To investigate the aromaticity and electronic delocalization in these novel macrocyclic systems.
- To explore the stability and spectral properties of these compounds under different protonation states.
Main Methods:
- Acid-catalyzed condensation reactions.
- Proton Nuclear Magnetic Resonance (NMR) spectroscopy.
- UV-vis spectroscopy.
- Nuclear Independent Chemical Shift (NICS) calculations.
- Anisotropically Induced Current Density (AICD) plots.
Main Results:
- Successful synthesis of azulichlorins and benzocarbachlorins.
- Azulichlorin monocations show strong diatropicity with internal C-H signals around -2 ppm.
- Benzocarbachlorin exhibits strong aromaticity with an internal C-H at -4.64 ppm and a 22π electron delocalization pathway.
- Protonation state significantly influences aromatic ring currents and electronic properties.
Conclusions:
- Azulichlorins and benzocarbachlorins represent new classes of macrocyclic compounds.
- The fused benzo unit in benzocarbachlorins facilitates a 22π electron delocalization pathway.
- Protonation state critically affects the electronic structure and aromaticity of these systems.
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