Proaromaticity: Organic charge-transfer chromophores with small HOMO-LUMO gaps

Yi Lin Wu, Filip Bureš, Peter D. Jarowski, W. Bernd Schweizer, Corinne Boudon, Jean Paul Gisselbrecht, François Diederich*

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    41 Scopus citations

    Abstract

    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, 1H 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.

    Original languageEnglish (US)
    Pages (from-to)9592-9605
    Number of pages14
    JournalChemistry - A European Journal
    Volume16
    Issue number31
    DOIs
    StatePublished - Aug 16 2010

    Keywords

    • Annulenes
    • Aromaticity
    • Computational chemistry
    • Conjugation
    • Donor-acceptor systems

    ASJC Scopus subject areas

    • Catalysis
    • Organic Chemistry

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