Synthesis and Structure of Alkyl-Substituted Fused Thiophenes Containing up to Seven Rings

We have established a series of synthetic methods to synthesize alkyl-substituted fused thiophenes with
degrees of fusion from two to seven rings. These fused thiophene ring compounds have very good solubility
in common organic solvents, making possible the solution processing of these compounds for electronic
applications. The UV absorption of these fused thiophenes is blue-shifted when compared with their
hydrocarbon counterparts. The larger band gaps result in much better stability. Single-crystal X-ray results
for 3,6-didecanyldithieno[2,3-d:2‘,3‘-d‘]thieno[3,2-b:4,5-b‘ ‘]dithiophene (FT5) and 3,7-didecanylthieno[3,2-b]thieno[2‘,3‘:4,5]thieno[2,3-d]thiophene (FT4) demonstrate that both compounds form π-stacking
structures instead of a herringbone-type of packing motif. This more favorable π-stacked structure may
lead to better material electronic properties such as mobility in devices fabricated with these compounds.