Aggregation-induced emission active seminaphthofluoresceins: a new class of xanthene luminogens for bioimaging

]xanthenes, π-extended fluorescein derivatives) yields luminogens exhibiting high Stokes shifts, bathochromically shifted emission, and aggregation-induced emission behaviour. The optical properties of the seminaphthofluorescein propargyl ethers, possessing terminal alkyne moieties for facile customization, are assessed both in the dissolved state and throughout the aggregation process. As a result of their controlled response to non-solvents over a broad range of solution compositions, the luminogens are suited for the optical sensing of water content in organic solvents. The aggregates were utilized for organelle imaging in microglia, the immune cells of the brain, and accumulated predominantly in the mitochondria. When coupled with their limited reliance on membrane potential, these findings suggest the luminogens as novel and versatile tools for intracellular visualization, tracking, and interactions of mitochondria with other organelles.