Design,Synthesis And Application Of Responsive Phosphorescent Iridium Complexes As PH And Oxygen Sensors And Photosensitizers

Various substances in organisms such as metal cations,anions,reactive oxygen/nitrogen species,mercaptans,amino acids and enzymes are important factors affecting biological physiology.At the same time,changes in the intracellular microenvironment(such as pH,viscosity,temperature,oxygen,etc.)also have a significant impact on the normal performance of cell functions.The imbalance of cell homeostasis may lead to abnormal metabolism of the body,which in turn induces various diseases,including cancer,Alzheimer's disease,etc.Therefore,the accurate detection of intracellular parameters is of great significance.The phosphorescent iridium(?)complex has the advantages of easy modification of the structure,great photostability,good biocompatibility,high quantum efficiency,and large Stokes shift.At the same time,time-resolved photoluminescence technique can be used to distinguish the long-lived phosphorescence signal from the background autofluorescence signal in the biological environment to improve signal-to-noise ratio,making the phosphorescent iridium(?)complexes have better applications in biosensing and bioimaging.The purpose of this thesis is to develop new phosphorescent iridium(?)complex materials and study their applications in pH,oxygen detection and as photosensitizer for photodynamic therapy.The main research contents include:1.Design,synthesis and application of pH-responsive phosphorescent iridium(?)complex probeCyclometalated iridium(?)complexes Ir-1-Ir-3 were designed to study their luminescence responses to different pH environments.2-(2-pyridyl)benzothiophene constituted the cyclometal ligand of the iridium(?)complexes,the derivatives of terpyridine and bipyridine as their auxiliary ligands.First,the structures of Ir-1-Ir-3 were characterized,and then their photophysical properties and pH responses were studied by ultraviolet-visible absorption spectroscopy,emission spectra and fluorescence spectrometers.The dates show that Ir-1-Ir-3 have good responses to pH and Ir-1 has a wider pH detection range.Ir-1 was chosen for further cell imaging research.The bioimaging of Ir-1under different pH environments in He La cells was detected by confocal laser scanning microscope,and the phosphorescence lifetime of the intracellular complex Ir-1 was further investigated by time-resolved luminescence imaging.The results show that the complex Ir-1 has geat performance on the detection of intracellular pH.2.Design,synthesis and application of phosphorescent iridium(?)complex as oxygen sensors and photosensitizersUsing the sensitivity of the phosphorescence of iridium(?)complexes to oxygen molecular,the cyclometalated iridium(?)complexes Ir-4-Ir-5 and Ir-1 were used to explore their responses to oxygen and the singlet oxygen(¹O₂)generation efficiency.The structures of the complexes were characterized by ¹H NMR and MS,and their photophysical properties were then studied.The results show that the complex Ir-4 has oxygen responsiveness and the ability to sensitize singlet oxygen formation.Through bioimaging experiment,it is further proved that Ir-4 can not only realize intracellular hypoxia imaging,but also as photosensitizer,Ir-4 has excellent performance in the singlet oxygen generation and promising application potential in photodynamic therapy.