Synthesis and properties of naphthobisbenzo[b]thiophenes: structural curvature of higher acene frameworks for solubility enhancement and high-order orientation in crystalline states

The syntheses of naphtho[2,3-b:7,6-b′]- and naphtho[2,1-b:5,6-b′]bisbenzo[b]thiophenes (NBBTs) are achieved via inter- and intramolecular stepwise Friedel–Crafts-type reactions. The structural curvature of these NBBTs are found to improve their solubility in organic solvents, and to form well-defined herringbone structures in single crystals, especially when the C2v symmetrical naphtho[2,3-b:7,6-b′]bisbenzo[b]thiophene takes the form of asymmetric space groups in a parallel direction with each other, and having exhibited OFET characteristics with a hole mobility of 7 × 10−5 cm2 V−1 s−1.