LAUSR

Abstract The 2-(2-hydroxyphenyl)-benzothiazole (HBT) fluorophore has attracted considerable attention due to its excited-state intramolecular proton transfer (ESIPT) based emission and its large Stokes shift. However, this fluorophore possesses several disadvantages including low quantum yield and short emission in the blue range. In this study, by coupling HBT at the ortho-, meta-, and para-positions to the hydroxyl group with different heterocycles to extend the conjugation system, we have successfully obtained new fluorophores with tunable emissions both in solution and in the solid-state (409–652 nm). Notably, all of the derivatives demonstrated improved quantum yields compared with the parent HBT structure. Moreover, selected compounds have been shown to shine brightly in live cells, indicating promising potential for bioimaging.