π-Expanded butterfly-like 2D fluorenes and 3D spirobifluorenes 1-5 were synthesized via a DDQ-mediated oxidative cyclization strategy with a high regioselectivity. Through structural modification via π-expansion, it was possible to achieve near-ultraviolet absorption, bright-blue emission, very high near-unity fluorescence quantum yields in solution as well as in film states, and deep-lying HOMO energy levels with excellent thermal stabilities. Furthermore, these electron-rich compounds displayed a notable behavior towards sensing of nitroaromatic explosives, such as picric acid, up to a detection limit of 0.2 ppb.

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Differently-linked bithienyl-attached fluorenes have been synthesized. While the oxidative photodicyclization of 2,3'-bithiophene-containing fluorene was successful to yield tetrathieno-fused regioisomeric π-expanded fluorenes, the reaction with 2,2'-bithiophene-containing fluorene was very sluggish. Interestingly, the connectivity in bithiophenes appears to determine the (photo)reactivity. On the one hand, under mild Scholl conditions, 2,3'-bithiophene-containing fluorene yielded a highly regioselective product while 2,2'bithiophene-containing fluorene led to polymerization. The optical and electrochemical properties of tetrathienoannulated π-expanded fluorenes were investigated, and they were found to be quite different from those of the phenanthrenoannulated π-expanded analogues. These newly obtained sulfur-edged π-expanded fluorenes may hold promise in organic electronics.

Various π‐extended new bitriphenylene derivatives (both conformationally‐free and conformation‐locked) have been successfully synthesized by a facile Scholl oxidative cyclodehydrogenation method in good to excellent yields. Their optical properties in solution and film states reveal possibility for self‐ordering. The molecular packing in solid‐state demonstrates favorable π–π stacking as well as weak intermolecular interactions leading to face‐to‐face or slipped‐stack arrangements. Besides, these butterfly‐shaped large bitriphenylenes display near‐UV absorption, excellent photochemical, thermal, and electrochemical stabilities. The all‐organic anneal‐free transparent FETs fabricated from solution‐processable bitriphenylenes showcase significant improvement (ca. 4 orders of magnitude higher) in charge transporting abilities (µh: from ca. 10–7 to 10–3  cm2/(Vs)) when compared to model triphenylene. The fabricated FETs unveil excellent air stability (> 1 year under atmospheric conditions) highlighting the utility of these novel link‐locked triphenylene skeletons in organic electronics.