Trisulfur radical anion-triggered stitching thienannulation: rapid access to largely π-extended thienoacenes.

Largely π-extended rylene diimide-fused thienoacenes, a new family of fully fused electron donor-acceptor (D-A) molecules, have been readily synthesized by a novel trisulfur radical anion (S3˙-)-triggered stitching thienannulation strategy. The ladder-type fused thiophene cores are constructed in a stitching manner through multiple carbon-sulfur bond formation between acetylenic rylene dyes and S3˙-. A detailed mechanistic study of these stitching thienannulations unveiled the multiple reactivities of S3˙-. Physical properties of the newly formed D-A, A-D-A, and D-A-D type thienoacenes have also been investigated, which revealed their precisely controllable electronic properties.