The development of straightforward synthetic methods for photoactive polycyclic aromatic hydrocarbons (PAHs) that avoid Pd-catalyzed or radical-based processes remains a challenge for a synthetic chemists. Such methods are essential to not only reducing the cost, but also to reducing their environmental impact that is of paramount importance in the context of their prospective use as emitters in optoelectronic devices.
In this work, we present a one-pot synthetic approach for creating novel bipolar PAHs with extended π-conjugation, which are not accessible via conventional Pd-catalyzed routes. Our cascade process operates exclusively under basic conditions, utilizing cesium carbonate and molecular sieves to facilitate the coupling of electron-deficient 4-fluoronaphthalene-1,8-dicarboximide with halogenated electron-rich moieties. This results in the regio- and chemoselective formation of new 6- and/or 5-membered conjugated rings via consecutive SNAr reactions, as confirmed through experimental and computational studies. The resulting PAHs exhibit strong emissive properties, with quantum yields ranging from 34% to 99%. This work provides a simple and efficient synthetic strategy for producing novel semiconducting materials, offering a new framework for designing bipolar PAHs with distinct optical characteristic
K. Bartkowski, E. Masoumifeshani, M. Kotowska, U. Klimczak, B. Furman, C. Foroutan-Nejad, M. Lindner, “One-Pot Transition-Metal-Free Synthesis of π-Extended Bipolar Polyaromatic Hydrocarbons”, Angew. Chem. Int. Ed.