Microwave-assisted synthesis of new triangulenium dyes for lifetime imaging microscopy (FLIM)

We introduce a novel microwave-assisted method for the rapid and efficient synthesis of triangulene dyes, enabling the creation of a broader range of these fluorophores, which are characterized by very long fluorescence lifetimes. We prepared different azadioxatriangulenium (ADOTA) and diazaoxatriangulenium (DAOTA) derivatives and thoroughly characterize their pho- tophysical properties. We investigated their solvatochromic properties and effects from solvent, aided by computational chemistry results. We employed the new ADOTAs and DAOTAs in different modalities of microscopy in cellulo, including confocal, fluores- cence lifetime imaging microscopy (FLIM), and super-resolution structured illumination microscopy (SIM). Most of the candidates accumulate in mitochondria, where they undergo electron transfer-driven quenching, which makes them exceptionally well-suited for providing distinct contrast for mitochondrial identification in FLIM microscopy.