Hydrophilic, Red-Emitting, and Thermally Activated Delayed Fluorescence Emitter for Time-Resolved Luminescence Imaging by Mitochondrion-Induced Aggregation in Living Cells.

Thermally activated delayed fluorescence (TADF) materials have provided new strategies for time-resolved luminescence imaging (TRLI); however, the development of hydrophilic TADF luminophores for specific imaging in cells remains a substantial challenge. In this study, a mitochondria-induced aggregation strategy for TRLI is proposed with the design and utilization of the hydrophilic TADF luminophore ((10-(1,3-dioxo-2-phenyl-2,3-dihydro-1H-benzo[de]isoquinolin-6-yl)-9,9-dimethyl-9,10-dihydroacridin-2-yl)methyl)triphenylphosphonium bromide . Using a nonconjugated linker to introduce a triphenylphosphonium (TPP) group into the 6-(9,9-dimethylacridin-10(9)-yl)-2-phenyl-1H-benzo[]isoquinoline-1,3(2)-dione TADF luminophore preserves the TADF emission of . shows clear aggregation-induced delayed fluorescence enhancement behavior, which provides a practical strategy for long-lived delayed fluorescence emission in an oxygen-containing environment. Finally, the designed mitochondrion-targeting TPP group in induces the adequate accumulation of and results in the first reported TADF-based time-resolved luminescence imaging and two-photon imaging of mitochondria in living cells.