Asymmetrical/Symmetrical D-π-A/D-π-D Thiazole-Containing Aromatic Heterocyclic Fluorescent Compounds Having the Same Triphenylamino Chromophores

A family of linear asymmetrical D-pi-A and symmetrical D-pi-D types of thiazole-based aromatic heterocyclic fluorescent compounds bearing various electron-donating and electron-withdrawing tails (bromo, triphenylamino, pyridyl, thienyl and benzoic acid) have been designed and prepared successfully. Synthetic, structural, thermal, spectral and computational comparisons have been carried out for related compounds because of their adjustable electronic properties. It is interesting to mention that compound 2 can be prepared from 5-bromothiazole by one-pot Suzuki-Miyaura coupling and subsequent C-H activation reactions via a 5-TPA-substituted thiazole intermediate 1. X-ray single-crystal structures of six compounds indicate that they all crystallize in the triclinic P (1) over bar space group and the thiazole core exhibits different dihedral angles with its adjacent benzene ring of the triphenylamino group (3.6(3)-40.8(3)degrees). The photophysical and electrochemical results demonstrate that compound 7 exhibits high electrochemical activity with a green fluorescence emission. Meanwhile, compounds 1, 2, and 6 show high luminescence quantum yields, and compound 8 exhibits excellent thermal stability (T-d10 = 503 degrees C).