Highly distorted polycyclic aromatic hydrocarbons (PAHs) are predicted to be attractive goals in nanoscience owing to the new properties they can exhibit. We have shown that a variety of functionalized distorted heptagon-containing nanographenes can be easily prepared from simple building blocks by a sequence of Co-catalyzed cyclotrimerization and cyclodehydrogenation reactions. The versatility of this strategy allows easy subsequent enlargement of these nanostructures by Ni-catalyzed cross-coupling and final cyclodehydrogenation reactions. Soluble extended distorted nanographenes 1 and 2 containing heptagon and an edge-shared pentagon–heptagon combination have been synthesized. High distortion of the polycyclic backbone of 2 caused by non-hexagonal rings and a helicene moiety was confirmed by X-ray crystallography. Experimental data reveal promising optical and electronic properties for distorted PAHs with long fluorescence lifetimes (up to 14.5 ns) and low band gaps (down to 2.27 eV). This straightforward and versatile synthetic strategy, the observed long fluorescence lifetimes and the small optical and electrochemical band gaps for the presented compounds may promote the future implementation of distorted graphene molecules in electronic devices.
†Electronic supplementary information (ESI) available: General details, synthesis and spectroscopy data of new compounds and copies of 1H and 13C-NMR spectra of new compounds. Experimental details on optical and electrochemical measurements. Crystal data and structure refinement of compounds 2, 6a, 6d and 6h. Further details on theoretical calculations and Cartesian coordinates of computed structures. VT- 1H-NMR, 2D-NMR and HRMS spectra of compounds 1 and 2. CCDC 1485682–1485685. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c6sc02895k