Phosphorescent Ir(?) Complexes:Design,Synthesis And Applications In Luminescence And Lifetime Confocal Imaging Microscopy In Cells

Cells are the basic units of living organisms.Simultaneous monitoring of two or more subcellular structures involved in the same physiological activity is beneficial to understanding life activity and pathogenesis mechanism.Fluorescence/phosphorescence imaging microscopy has been widely used in biomedical detection and imaging because of its high sensitivity,high spatial resolution and low damage to biosamples.However,in the process of luminescence imaging,traditional fluorescence probes usually suffer from interference of auto-fluorescence,variability of probe concentrations and fluctuation of laser power.By utilizing the long-lived luminescent probes,the interference from environmental conditions could be effectively minimized via time-resolved luminescence technology.Transition metal complexes are suitable for bioimaging because of their excellent photophysical properties.Meanwhile,the long emission lifetime in microsecond scales renders them ideal probes for time-resolved luminescence imaging.In this work,a series of phosphorescent iridium(?)complexes has been designed for luminescence and lifetime confocal cellular imaging.The main contents of this research include:1.A series of bis(2-phenylquinoline)iridium(?)complexes Ir1-Ir4 using bipyridine derivatives as the diimine ligands has been designed,synthesized,and characterized.Their cellular imaging performance has been investigated via co-localization luminescence imaging and photoluminescence lifetime imaging.Interestingly,complex Ir1 with an ester substituted diimine ligand underwent internalization into cell nuclei,while complexes Ir2-Ir4 were concentrated in the cytoplasm.Endocytosis tests and cell cycle imaging have been performed to further understand the nucleus-staining process.The resluts in this work provide a new design strategy for developing novel probes for cell nuclear targeting.2.Phosohorecent iridium(?)complex Ir5,with carboxyl groups in main ligands and two linear C9 carbon chains in the diimine ligand,has been designed,synthesized and characterized.Ir5 has been observed to target cell membranes successfully via luminescence confocal cellular imaging.By using the special cell-staining performance of Ir1,the cell membranes,cytoplasm and nucleus can be effectively distinguished in photoluminescence lifetime imaging after co-staining with Ir1 and Ir5,which offers guidlines for observing subcellular structure simultaneously.