Synthesis, π‑Stacking and Application of Tetraethynyl Dioxotriangulenes

4,8-Dioxotriangulene (DOT) features a triangulene core functionalized with two carbonyl groups, which stabilizes its radical anion through delocalization of negative charge and spin density across the extended π-framework. This study demonstrates that DOT derivatives serve as viable building blocks for n-type organic semiconductors. Tetraethynyl DOTs (1a-c) bearing triisopropylsilyl, trimethylsilyl, and butyl substituents, respectively, were successfully synthesized via an unprecedented formal Pd-catalyzed C-(Ar)-O bond activation of phenolic esters. Single-crystal X-ray analysis reveals 1a assembles into discrete π-stacked tetramers, while 1b forms a one-dimensional π-stack with substantial interplanar overlap. Electrochemical reduction of 1b generates a persistent radical anion confirmed by EPR and UV-vis spectroscopy. Solution-processed films of 1b function as n-type semiconductors in field-effect transistors.