Donor–Acceptor Ferrocenyl-Substituted Benzothiadiazoles: Synthesis, Structure, and Properties

This article reports the design, and synthesis of D−π1–A−π2–D unsymmetrical, and D−π1–A−π2–A−π1–D symmetrical type of ferrocenyl-substituted benzothiadiazoles by the Pd-catalyzed Sonogashira, and Stille coupling reactions. The photophysical and electrochemical behavior of the ferrocenyl-substituted benzothiadiazoles show strong donor–acceptor interaction. The increase in the number of acceptor benzothiadiazole unit, results in the lowering of the energy gap, which leads to the bathochromic shift of the absorption spectrum. The single crystal X-ray structures of 3a, 5a, and 5g were obtained which show interesting supramolecular interactions.