Design And Synthesis Of Phosphorescent Iridium(Ⅲ) Complexes And Their Bioimaging Applications

With the development of optical imaging technology, bioimaging has become an importantmeans to understand organism processes from cell level, such as cell signal transduction andapoptosis, and playing an increasingly important role in life science and pathology. Currently, thebioimaging is mainly regarded as two categories in virtue of different photophysical properties,namely, fluorescence bioimaging and phosphorescence bioimaging. To date, the researchesconcentrated on organic fluorescent dyes used for fluorescence imaging are more widespread thanphosphorescent ones. However, the drawbacks of fluorescent dyes limit the application offluorescent dyes in the field of imaging, such as short lifetime, light bleaching and low quantumefficiency. It makes the development of new biological probes great significant. Recently,phosphorescent complexes obtained with prominent photophysical properties, such as Pt(II), Ru(II),Re(I), Ir(III), Cu(I), Au(I) and Os(II) complexes, worked as biological probes have attracted a greatdeal of attention in bioimaging field. Iridium(III) complexes are capable of the excellent physicalproperties, such as long lifetime, high quantum yield, excellent color tunability, long wavelength ofthe visible light for excitation. They also possess remarkable chemical stability and outstandingbiocompatibility. And they have exhibited promising application in the fields of chemosensing andbiolabeling.In this thesis, we designed and synthesized the phosphorescent complexes to implement twodifferent purposes, two kinds of ionic iridium(III) complexes, one sensor based on the specificreaction of the aldehyde group cyclization with special amino acid, cysteine/homocysteine; theother one based on the sensitivity for oxygen is used as an oxygen sensor. These probes have provedwith excellent detection performance, lower cytotoxicity and brilliant cell membrane penetrationcapacity, which make these sensors be qualitied into advanced application for cell imaging.Firstly, we have designed and synthesized three kinds of phosphorescent probes with the sameN^N ligand and distinguished C^N ligand. Probe2performances best excellent detection functionand selectivity among the three probes so that we carry out bioimaging on probe2. It is evident thatluminescence intensity of cells are obviously augmented with the presence of Cys/Hcy. What’smore, MTT assay shows that probe2is poor biological toxicity. It comes into conclusion that probe2is capable of brilliant sensor worked as a prominent platform for Cys/Hcy detection andbioimaging. Secondly, we have designed and synthesized three kinds of phosphorescent probes with thesame N^N ligand and distinguished C^N ligand for oxygen sensor. Probe S3performances bestexcellent detection function among the three probes so that we carry out bioimaging on probe S3. Itis evident that luminescence intensity of cells are obviously enhanced with the absence of oxygen.Moreover, MTT assay shows that probe S3is poor biological toxicity. It comes into conclusion thatprobe S3is capable of brilliant sensor worked as a prominent platform for oxygen detection andbioimaging.