Design,synthesis And Application Of Mitochondria-Targeted Iridium(Ⅲ) Complexes Phosphorescence Probes

Transition-metal complexes have many advantages over organic fluorescent molecules.Their photophysical properties and interaction with biomolecules can be realized by adjusting ligands,and transition metal complexes have large Stokes shifts and long lifetimes.These characteristics make them useful for fluorescent probes and cell imaging.Mitochondria are an important organelle in eukaryotic cells that act as a source of energy for the production of cellular energy by oxidizing phosphate and play a key role in the cell death pathway.The pathogenesis of various diseases is associated with mitochondrial dysfunction,such as Parkinson’s disease(PD).Therefore,research on targeted imaging of mitochondria to achieve indirect identification and monitoring is also a research hotspot in the field.At present,there are few studies on mitochondrial imaging based on phosphorescence.In this paper,mitochondrial targeting units are introduced into phosphorescent ruthenium complexes,and specific groups that respond to redox species are introduced to achieve mitochondria-targeted phosphorescence.Imaging and monitoring of specific substances.The main research contents are as follows:First,we introduced a thiol unit capable of specifically reacting with hypochlorous acid on the N^C ligand 4-(2-pyridyl)benzaldehyde,and introduced an energy target on the carbon chain of the N^N ligand.To the mitochondrial triphenylphosphine unit,a synthetic Iridium(Ⅲ)Complexes Ir1 was designed.The molecular structure was characterized using mass spectrometry and nuclear magnetics.We used UV-Vis absorption spectroscopy and emission spectroscopy to characterize the responsiveness and selectivity of complex Ir1 to hypochlorite.In methanol buffer solution,the maximum absorption wavelength of the complex is 290 nm.After adding hypochlorous acid,the maximum absorption increased.The complex Ir1 does not emit light in the solution.As the HClO increases,it emits at 550 nm,and the emission peak gradually increases.When the added hypochlorous acid reaches 39 times equivalent,the fluorescence emission reaches the strongest.The emission intensity of the maximum emission peak has been greatly increased by 15 times,and the "Turn-on" type detection of hypochlorous acid has been realized.The fluorescence spectrum of the probe Ir1 did not change substantially with respect to other oxidizing ions,indicating that the probe Ir1 has a good selectivity for hypochlorous acid.The detection of cytotoxicity indicates that the complex probe is less biotoxic and can be used in biological cells.In the cell imaging experiment,the ruthenium complex probe Ir1 can detect hypochlorous acid in cells by fluorescence.Co-staining experiments showed that the probe specifically targeted mitochondria with a target co-staining coefficient of 94%,which can effectively detect hypochlorous acid produced on mitochondria.Second,we introduced an aldehyde group unit capable of specifically reacting with hydrogen sulfite on the N^C ligand 4-(2-pyridyl)benzaldehyde,and introduced energy into the carbon chain of the N^N ligand.The triphenylphosphine unit targeting mitochondria was designed to synthesize the Iridium(Ⅲ)Complexes Ir2.Mass spectrometry and nuclear magnetic characterization of its molecular structure.We used UV-visible absorption and emission spectroscopy to characterize the responsiveness and selectivity of the complex Ir2 to bisulfite.The absorption wavelengths of the complexes are at 280 nm and 320 nm.When no sulfite ion was added,the absorption peak was remarkable,and after the addition of the sulfite ion,the absorption peaks at 280 nm and 320 nm were remarkably lowered.The emission wavelength of the complex Ir2 is 550 nm.With the increase of bisulfite ion,the emission peak at 550 nm is obviously reduced.When the added hypochlorous acid reaches 50 times equivalent,the fluorescence emission does not change any more.Ir2 can effectively detect bisulfite and achieve "Turn-off" type detection.Cell imaging experiments demonstrated that the ruthenium complex probe Ir2 can easily detect bisulfite in cells by fluorescence.