Zig-zag nanographenes are promising candidates for the applications in organic electronics due to the electronic properties induced by their periphery. However, the synthetic access to these compounds remains virtually unexplored. There is a lack in efficient and mild strategies origins in the reduced stability, increased reactivity, and low solubility of these compounds. Herein we report a facile access to pristine zig-zag nanographenes, utilizing an acid-promoted intramolecular reductive cyclization of arylaldehydes, and demonstrate a three-step route to nanographenes constituted of angularly fused tetracenes or pentacenes. The mild conditions are scalable to gram quantities and give insoluble nanostructures in close to quantitative yields. The strategy allows the synthesis of elusive low bandgap nanographenes, with values as low as 1.62 eV. Compared to their linear homologues, the structures have an increased stability in the solid-state, even though computational analyses show distinct diradical character. The structures were confirmed by X–ray diffraction or scanning tunneling microscopy.
Herein, we report a new method for synthesis of extended perylenes and terrylenes. The technique is based on the cascade dehydrative π-extensions (DPEX) of aryl aldehydes, in which stepwise annulations activate previously "dormant" substituents. Two-and fourfold cyclizations of 3-aryl-biphenyl-2,2'-dicarbaldehydes offer a rapid path to unsymmetrical perylenes and elusive terrylene derivatives, respectively. DPEX of 3,3''-(phenanthrene-1,8-diyl)bis (([1,1'biphenyl]-2,2'-dicarbaldehyde)) leads to the biradical structure, which proceeds in situ into oxidative electrocyclization at room temperature. The described domino process complements and expands DPEX approach to a large family of fused acenes and related PAHs.
Herein, we present a modular approach
to pristine angularly fused
planar acenes. The approach includes the Pd-catalyzed fusion of several
building blocks and implements a dehydrative π-extension (DPEX)
reaction as a key step enabling facile access to diverse two-dimensional
acenes. The scope was demonstrated on nine examples with up to quantitative
yield.
An unprecedented [6]helicene's cavity closure indicating the possibility of introducing seven-membered rings via alumina-mediated C–F activation is shown.
Supporting information and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.Figure 5. Graphical representation of the DFT-based thermochemical analysis. The DH values( kcal mol À1 )f or the fluorinated precursors and corresponding scomplexes are referenced to the lowest valuei ne ach separate step.
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