Dedicated to Professor Eun Lee on the occasion of his retirement and 65th birthdayOrganic photovoltaic (OPV) devices [1][2][3][4] are attracting much attention as a new source of renewable energy. A major chemical interest in this area of research lies in the development of new organic semiconductors. Molecular design endows in an organic compound either a hole-transporting (p-type), electron-transporting (n-type), or ambipolar property through the incorporation of heteroatoms and new conjugation systems to the basic carbon framework. [5][6][7][8] The design of p-type semiconductors usually consists of installing electron-donating amino substituents on an aromatic system to raise the HOMO level. We recently discovered the p-type semiconductor properties of benzodifurans, and found it interesting that furans have received much less attention than thiophene and pyrrole semiconductors. This observation led us to explore a variety of aromatic rings bearing electron-deficient heteroatoms that may generally serve as n-type materials, which are less easy to design, and hence less-developed than the p-type materials. [5,6,[9][10][11][12][13][14][15] Herein, we report that a naphthalene-type molecule bearing two nitrogen atoms called cinnoline (Scheme 1) shows good n-type characteristics together with favorable thermal and morphological stabilities and high electron mobility (up to the order [a] Dr.
Synthesis of 1,3-bis(3,4-Diphenylcinnolin-8-yl)benzene (p8-BCB)8-Bromo-3,4-diphenylcinnoline (240 mg, 0.665 mmol), 1,4-phenylenediboronic acid (54.4 mg, 0.328 mmol), PdA C H T U N G T R E N N U N G (PPh 3 ) 4 (75.8 mg, 0.0656 mmol), and Na 2 CO 3 (153 mg, 1.44 mmol) were added to degassed H 2 O (0.769 mL), EtOH (0.56 mL), and toluene (1.75 mL). The mixture was stirred at 120 8C for 18 h. After cooling to room temperature, the reaction was quenched with saturated aqueous NH 4 Cl. The mixture was filtered and washed several time with dichloromethane to give the title compound as a yellow solid (72.2 g). The filtrate was extracted with chloroform. The combined organic layers were dried over MgSO 4 and concentrated in vacuo. Recrystallization from toluene afforded the title compound as a yellow solid (78.0 mg), (total 150 mg, 0.235 mmol, 72 %). Mp: 338-339 8C. 1 H NMR (500 MHz, CDCl 3 ): d = 7.26-7.30 (m, 6 H, ArH), 7.33-7.35 (m, 4 H, ArH), 7.45-7.47 (m, 6 H, ArH), 7.53-7.55 (m, 4 H, ArH), 7.77-7.81 (m, 4 H, ArH), 7.96-7.98 (m, 4 H, ArH), 8.05 ppm (s, 4 H, ArH). 13 C NMR (125 MHz, CDCl 3 ): d = 125.0