Syntheses and properties of 11-ring-fused linear thienoacenes

A novel class of π-extended 11-ring-fused linear thienoacenes (BBDTB-H, BBDTB-TIPS, and BBDTB-Br) with four thieno[3,2-b;4,5-b′]dithiophenes and three benzene rings were synthesized and fully characterized. The photophysical, electrochemical, and thermal properties of thienoacenes with different fused lengths and substituent groups were systematically investigated. These conjugated aromatic thienoacenes exhibit good stability compared to acenes. A single crystal of BBDTB-TIPS is obtained and the molecular length is calculated to be 22.42 Å, which is the longest reported single crystal of a linear thienoacene. The aromaticity of every ring in BBDTB-H is calculated by the nucleus-independent chemical shift (NICS) and anisotropy of the induced current density (ACID). Finally, preliminary investigations on thienoacene based organic field effect transistors (OFETs) are reported.