Synthesis And Bioimaging Application Of Iridium Complexes With Red-Light Or Near Infrared Luminescence

With the rapid development of life sciences,bioimaging technology has become an important approach to achieve the molecular and cellular level for biological processes.Based on the excellent cell permeability,low cytotoxicity and good anti-bleaching properties of red-to-near-infrared?NIR?light-emitting probes in bioimaging,this thesis aims to develop new red-to-NIR light-emitting probe materials.Firstly,three novel neutral phosphorescent iridium complexes with typical NIR luminescence were synthesized by complexing the HC^N main ligand with different complementary ligands?N^O?.Secondly,based on the hydrophilic properties of ionic iridium complexes,three ionic iridium complexes with red or NIR luminescence were synthesized by the coordination of the different main ligands Hdpqx,Hiqbt,Hdpbq?C^N?with the auxiliary ligand 4VBPY?N^N?,respectively.At the same time,iridium complexes were designed as phosphorescent materials for cell imaging.Its main contents are as follows:In part one,using Hdpbq?C^N?as the main ligand and one of the three complementary?N^O?Schiff-base ligands HL¹,HL² and HL³?HL¹ =?Z?-2-??phenylimino?methyl?phenol,HL² =?E?-2-methoxy-6-??phenylimino?methyl?phenol,HL³ =?E?-2,4-di-tert-butyl-6-??phenylimino?methyl?phenol?as the ancillary ligand,their reaction with Ir Cl₃·3H₂O was used to obtain the three novel neutral iridium complexes [Ir?dpbq?2?L¹?],[Ir?dpbq?2?L²?] and [Ir?dpbq?2?L³?] with NIR??em = 780 nm?luminescence,respectively.For[Ir?dpbq?2?L¹?],the phosphorescent lifetime is 1.47 ?s,and the quantum yield is 0.17.For[Ir?dpbq?2?L²?],the phosphorescent lifetime is 1.64 ?s,and the quantum yield is 0.17.For[Ir?dpbq?2?L³?],the phosphorescent lifetime is 1.87 ?s,and the quantum yield is 0.16.Moreover,their electrochemical properties and theoretical calculations were studied.In part two,through the reaction of one of the different main ligands Hdbqx,Hiqbt,Hdpbq?Hdbqx=2,3-diphenylquinoxaline,Hiqbt = 1-?benzo[b]thiophen-2-yl?isoquiline??C^N?and the same auxiliary ligand?N^N?4VBPY(4VBPY = 2-?5-?4-vinylphenyl?pyridin-2-yl?with Ir Cl₃·3H₂O and NH₄PF₆,three new ionic iridium complexes [Ir?dpqx?₂?4VBPY?]+PF₆^-,[Ir?iqbt?₂?4VBPY?]⁺PF₆^-and [Ir?dpbq?₂?4VBPY?]⁺PF₆^-were prepared,respectively.Their photophycial property shows that the phosphorescent lifetime of [Ir?dpqx?₂?4VBPY?]+PF₆^-is0.736 ?s,??em = 630 nm?,and the quantum yield is 0.19.And the phosphorescent lifetime of[Ir?iqbt?₂?4VBPY?]⁺PF₆^-is 0.452 ?s??em = 683 nm?,and the quantum yield is 0.16.As to[Ir?dpbq?₂?4VBPY?]⁺PF₆^-,the phosphorescent lifetime is 0.224 ?s??em = 773 nm?,and the quantum yield is 0.22.Moreover,their electrochemical properties were also studied.Finally,the three ionic iridium complexes [Ir?dpqx?₂?4VBPY?]+PF₆^-,[Ir?iqbt?₂?4VBPY?]⁺PF₆^-and [Ir?dpbq?₂?4VBPY?]⁺PF₆^-were used for bioimaging,where their toxicity on A549 and Hep G2 cells incubation was detected by MTT(?3-?4,5-dimethyl-2-thiazole?-2,5-diphenyl tetrazolium bromide?assay.The results show that their cell survival rate is more than 80%under the concentration of less than 50 ?M,indicating that the three Ir?III?-complexes have relatively low cytotoxicity.Moreover,through their fluorescence imaging on A549 cells by confocal laser scanning microscopy,the bioimaging results show that Ir?dpqx?₂?4VBPY?]+PF₆^-and [Ir?iqbt?₂?4VBPY?]⁺PF₆^-could specifically stain cytoplasm,while[Ir?dpbq?₂?4VBPY?]⁺PF₆^-does not exhibits intracellular luminescence probably due to its much poor solubility in DMSO/PBS buffer.