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Peri‐thiaxanthenothiaxanthene, an S‐doped analog of peri‐xanthenoxanthene, is used as a polycyclic aromatic hydrocarbon (PAH) scaffold to tune the molecular semiconductor properties by editing the oxidation state of the S‐atoms. Chemical oxidation of peri‐thiaxanthenothiaxanthene with H2O2 led to the relevant sulfoxide and sulfone congeners, whereas electrooxidation gave access to sulfonium‐type derivatives forming crystalline mixed valence (MV) complexes. These complexes depicted peculiar molecular and solid‐state arrangements with face‐to‐face π–π stacking organization. Photophysical studies showed a widening of the optical bandgap upon progressive oxidation of the S‐atoms, with the bis‐sulfone derivative displaying the largest value (E00=2.99 eV). While peri‐thiaxanthenothiaxanthene showed reversible oxidation properties, the sulfoxide and sulfone derivatives mainly showed reductive events, corroborating their n‐type properties. Electric measurements of single crystals of the MV complexes exhibited a semiconducting behavior with a remarkably high conductivity at room temperature (10−1–10−2 S cm−1 and 10−2–10−3 S cm−1 for the O and S derivatives, respectively), one of the highest reported so far. Finally, the electroluminescence properties of the complexes were tested in light‐emitting electrochemical cells (LECs), obtaining the first S‐doped mid‐emitting PAH‐based LECs. [ABSTRACT FROM AUTHOR]

Herein we report an efficient synthesis to prepare O‐doped nanographenes derived from the π‐extension of pyrene. The derivatives are highly fluorescent and feature low oxidation potentials. Using electrooxidation, crystals of cationic mixed‐valence (MV) complexes were grown in which the organic salts organize into face‐to‐face π‐stacks, a favorable solid‐state arrangement for organic electronics. Variable‐temperature electron paramagnetic resonance (EPR) measurements and relaxation studies suggest a strong electron delocalization along the longitudinal axis of the columnar π‐stacking architectures. Electric measurements of single crystals of the MV salts show a semiconducting behavior with a remarkably high conductivity at room temperature. These findings support the notion that π‐extension of heteroatom‐doped polycyclic aromatic hydrocarbons is an attractive approach to fabricate nanographenes with a broad spectrum of semiconducting properties and high charge mobilities. [ABSTRACT FROM AUTHOR]