Coplanar bithiazole-centered heterocyclic aromatic fluorescent compounds having different donor/acceptor terminal groups.

A family of stable and soluble bithiazole-centered heterocyclic aromatic fluorescent compounds is described herein. All these multiple N-donor containing compounds have effective π-conjugated systems and different imidazole, pyridine, thiophene, triphenylamino, benzoic acid, and ethyl benzoate tails showing distinguishable D-A-A-D and A-A-A-A structures. X-ray single-crystal structures of seven compounds indicate that all of the bithiazole cores have the same trans coplanar configuration but exhibit different dihedral angles with their adjacent aromatic heterocycles (4.5(6)-69.7(3)°). Optical and electrochemical results demonstrate that the TPA-terminated bithiazole compound 2TPA2TZ has yellow fluorescence and reversible redox activity as well as extraordinarily high thermal stability. Theoretical and experimental studies have been made to reveal the differences from related compounds with adjustable electronic properties. The internal reorganization energy (λ) studies have been carried out to indicate the differences between the bithiazole-based derivatives and the corresponding bithiophene-based counterparts.