We report the syntheses, structures, photophysical properties, and redox characteristics of donor–acceptor-fused π-systems, namely π-extendedthiadiazoles 1–5 fused with thienopyrrole or indole moieties. They were synthesized by the Stille coupling reactions followed by the PPh3-mediated reductive cyclizations as key steps. X-Ray crystallographic studies showed that isomeric 1b and 2b form significantly