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.