Design,Preparation And Biological Applications Of Cationic Phosphorescent Iridium(Ⅲ) Complexes

Bio-optical imaging provides an intuitive visualization method for medical testing that enables in situ and non-invasive bioanalysis at the cellular level in real time and facilitates the disclosure of complex biological and physiological processes.In view of the advantages of phosphorescent probes,such as excellent sensitivity,long emission lifetime,spectral modulation,rapid response and easy synthesis,they have become the perfect choice in the biomedical fields.In this thesis,we have synthesized a series of phosphorescent iridium(III)complexes with different conjugated structures,studied their photophysical properties and investigated their applications in biological imaging and photodynamic therapy.In addition,we designed and prepared two ppy and 2fppy-based complexes and studied their aggregation-induced luminescence effects and realized their application in bioimaging.Firstly,a series of iridium(III)complexes based on triphenylamine and benzothiophene structures were desigened and synthesized by simple methods.After analyzing their photophysical properties and the yield of singlet oxygen at different excitation wavelengths,Ir5 was selected to apply in bioimaging and photodynamic therapy for tumor cells because of its near-infrared phosphorescence and high yield of singlet oxygen.In staining experiment,Ir5 was enriched in the mitochondria and was confirmed to have the function of targeting mitochondria.In the photodynamic therapy experiment,it was confirmed that Ir5 could produce singlet oxygen in the tumor cells,which can induce cell apoptosis for therapeutic purposes.Secondly,two phosphorescent iridium(III)complexes with ppy and 2fppy structures were designed and synthesized.Study results have shown that they do not emit light in tetrahydrofuran solution,but have bright long-lived phosphorescence in aggregated states such as solid powders.Two emissive pathways exist under different conditions.One is the luminescence from intramolecular charge transfer state in the free molecular state,and the other is aggregation induced luminescence in the aggregation state.In the subsequent biomedical experiments,the two complexes also showed good biocompatibility,which provided the basis for further functional modification and expansion.