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−π–A and symmetrical
D−π–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 P1̅ 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)°). 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 (Td10 = 503 °C).