Reaction Steps
A mixture of 1-iodo-4-octylbenzene (16.09 g, 35.1 mmol, 69% of purity) as prepared above, 5,11-dihydridoindolo[3,2-b]carbazole (3.00 g, 11.7 mmol), 18-crown-6 (0.62 g, 2.34 mmol), K2CO3 (12.94 g, 93.6 mmol), copper (2.97 g, 46.8 mmol), and 1,2-dichlorobenzene (50 mL) was charged into an argon-filled 200 mL flask fitted with a condenser. The mixture was heated under reflux in an argon atmosphere for 24 h. Subsequently, the reaction mixture was cooled down to room temperature, diluted with tetrahydrofuran, and filtered. A viscous liquid, obtained after removal of solvent on a rotary evaporator, was added to 400 mL of methanol with vigorous stirring. The precipitated yellow solid was filtered, washed several times with water and methanol, dissolved in 400 mL of hexane by heating, and filtered to remove the insoluble impurities. The filtrate was concentrated to about 50 mL and allowed to cool down to room temperature, and then chilled at 0° C. overnight. The crystallized yellow product was filtered, washed with a small amount of hexane, and dried to yield 5.32 g of 5,11-bis(4-octylphenyl)indolo[3,2-b]carbazole, compound (2), which was subject to train sublimation to obtain electrically pure compound for OTFT fabrication. DSC showed a melting point at 131° C. on first heating. 1H NMR (CDCl3): δ 8.12 (d, J=7.6 Hz, 2H), 8.05 (s, 2H), 7.58 (d, J=8.3 Hz, 4H), 7.47 (d, J=8.3 Hz, 4H), 7.39-7.40 (m, 4H), 7.19-7.21 (m, 2H), 2.78 (t, J=7.8 Hz, 4H), 1.78 (pent, J=7.4 Hz, 4H), 1.30-1.50 (m, 20H), 0.92 (m, 6H); IR (NaCl): 3047, 2956, 2923, 2852, 1517, 1451, 1324, 1236, 842, 731 cm−1.
