Journal article
Proaromaticity: organic charge-transfer chromophores with small HOMO-LUMO gaps.
- Wu YL Laboratorium für Organische Chemie, ETH-Zürich, Hönggerberg, HCI, 8093 Zürich, Switzerland.
- Bures F
- Jarowski PD
- Schweizer WB
- Boudon C
- Gisselbrecht JP
- Diederich F
- 2010-07-22
Published in:
- Chemistry (Weinheim an der Bergstrasse, Germany). - 2010
English
Novel donor- and/or acceptor-substituted cross-conjugated carbocycles based on quinoids or expanded quinoids, with radiaannulene perimeters, were prepared and investigated to validate proaromaticity as a concept for reducing HOMO-LUMO gaps in push-pull chromophores. Analyses of IR, (1)H NMR, and UV/Vis/NIR spectra in conjunction with molecular structures determined by X-ray diffraction show that these push-pull quinoids have significant charge-separated ground states. This feature results in small optical gaps (near IR region) and diatropic magnetic environments inside the carbocycles, as suggested by nucleus-independent chemical shift (NICS) calculations. The NICS results, together with the bond-length analysis of the quinoid spacers, provide strong support that proaromaticity, that is, aromatized zwitterionic mesomeric contributions in the ground state, is effective. A push-pull tetrakis(ethynediyl)-expanded quinoid chromophore represents the first proaromatic radiaannulene.
- Language
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- English
- Open access status
- closed
- Identifiers
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- DOI 10.1002/chem.201001051
- PMID 20648493
- Persistent URL
- https://sonar.ch/global/documents/167697
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