Synthesis, Molecular Engineering, and Photophysical Properties of Fluorescent Thieno[3,2-b]pyridine-5(4H)-ones

We describe a synthetic approach for a set of fluorescent thieno[3,2-b]pyridine-5(4H)-one derivatives and their photophysical properties. These fluorophores are prepared by a series of reactions employing the Suzuki–Miyaura cross-coupling reaction and a regioselective aza-[3 + 3] cycloaddition of 3-aminothiophenes with α,β-unsaturated carboxylic acids. Our findings revealed that the photophysical properties are chemically tunable by an appropriate choice of functional group on the thieno[3,2-b]pyridine-5(4H)-one scaffold.