O-doped nanographenes: the pyrano/pyrylium route towards semiconducting cationic mixed valence complexes

Luka Ðorđević, Cataldo Valentini, Nicola Demitri, Cécile Mézière, Magali Allain, Marc Sallé, Andrea Folli, Damien Murphy, Samuel Mañas-Valero, Eugenio Coronado, Davide Bonifazi
Angew. Chem. Int. Ed., 2019accepted.
DOI: 10.1002/anie.201914025


Herein we report an efficient synthesis to prepare O-doped nanographenes, which derive from the longitudinally and latitudinally p-extension of pyrene. The derivatives are highly fluorescent and feature low-oxidation potentials. Exploiting electrooxidation, crystals of cationic mixed valence (MV) complexes were grown in which the organic salts organize into face-to-face pp stacks, a favorable solid-state arrangement for organic electronics. Variable-temperature EPR measurements and relaxation studies suggest a strong electron delocalization along the
longitudinal axis of the columnar p-stacking architectures. Electric measurements of single crystals of the MV salts exhibited a semiconducting behavior with a remarkable high conductivity at room temperature. These findings further support the idea for which the
p-extension of polycyclic aromatic hydrocarbons featuring precise heteroatom doping topologies, is an attractive approach to enable
nanographenes with a broad spectrum of semiconducting properties and high charge mobilities.

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