Antiaromatic 1,5-Diaza-s-indacenes
Kensuke Hanida1, Jinseok Kim2, Norihito Fukui1
1Department of Molecular and Macromolecular Chemistry, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8603, Japan.
Angewandte Chemie (International Ed. in English)
|July 21, 2021
Summary
Researchers synthesized nitrogen-doped s-indacene analogues, 1,5-diaza-s-indacenes. These compounds display antiaromaticity and enhanced electron-accepting properties compared to the parent hydrocarbon.
Area of Science:
- Organic Chemistry
- Materials Science
- Supramolecular Chemistry
Background:
- s-Indacene is a non-alternant hydrocarbon with 12 π-electrons in a cyclic π-conjugation system.
- Nitrogen-doped analogues offer potential for novel electronic and optical properties.
Purpose of the Study:
- To synthesize and characterize 1,5-diaza-s-indacene, a nitrogen-doped analogue of s-indacene.
- To investigate the antiaromaticity and electronic properties of the novel compounds.
- To explore the tunability of their optical and redox characteristics.
Main Methods:
- Two-step synthesis involving palladium-catalyzed Larock cyclization.
- Hydrogen abstraction for final product formation.
- Spectroscopic and computational analyses to confirm structure and properties.
Main Results:
- Successful synthesis of 1,5-diaza-s-indacenes from 2,5-dichlorobenzene-1,4-diamine.
- Demonstrated distinct antiaromaticity, evidenced by bond-length alternation and a forbidden HOMO-LUMO transition.
- Observed enhanced electron-accepting ability due to imine-type nitrogen atoms.
- Showcased effective conjugation for tuning absorption spectra and redox properties.
Conclusions:
- 1,5-Diaza-s-indacenes represent a novel class of antiaromatic, nitrogen-doped hydrocarbons.
- These compounds exhibit tunable electronic and optical properties, making them promising for materials applications.
- The study provides insights into the structure-property relationships of antiaromatic systems.
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