Synthesis and Studies of Imidazoanthraquinone Derivatives for Applications in Organic Electronics

Imidazoanthraquinone derivatives with extended π conjugation were synthesized and characterized. Palladium-catalyzed Suzuki–Miyaura and Sonogashira couplings were employed to synthesize these derivatives. Photophysical and electrochemical studies of the new imidazoanthraquinone derivatives were performed, and their absorption and emission maxima were observed in a wide visible range. The photophysical studies revealed the formation of charge-transfer complexes. Cyclic voltammetry provided good estimates of the reduction and oxidation potentials of these compounds and eventually the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels. Electrochemical studies revealed low-lying ELUMO values of ca. –3.7 eV for these compounds. The donor–acceptor architecture and HOMO–LUMO energies were further studied through DFT calculations. On the basis of the ELUMO values of these compounds, photoquenching experiments were performed in the presence of the electron donor poly(3-hexylthiophene) (P3HT). These experiments suggest that these compounds could be used as electron acceptors in heterojunction solar cells.