Synthesis, characterization, and photophysical properties of some new thieno[2,3-b]pyridines bearing phenylethenyl moiety

5-Acetyl-3-cyano-6-methyl-4-(2-phenylethenyl)pyridine-2(1H)-thione (2) was synthesized by interaction of cinnamylidene-2-cyanothioacetamide 1 and acetylacetone or via one-pot reaction of E-cinnamaldehyde, 2-cyanothioacetamide, and acetylacetone. Reaction of 2 with ethyl iodide (3a) or N-chloroacetyl derivative of aromatic amines 3b-e in boiling ethanol containing sodium ethoxide gave the corresponding thioether 4a and 5-acetyl-3-amino-2-(N-arylcarbamoyl)-6-methyl-4-(2-phenylethenyl)thieno[2,3-b]pyridines 5b-e, respectively. Compound 5e was reacted with 2,5-dimethoxytetrahydrofuran or triethyl orthoformate to furnish pyrrolylthienopyyridine 6 or pyrdiothienopyrimidinone 7, respectively. The photophysical properties of 5b, 5c, 5e, and 7 were fully studied and the obtained results included herein. The fluorescence data confirmed that compounds 5b, 5c, 5e, and 7 exhibit aggregation-induced emission behavior with high absolute quantum yields.