The Design And Synthesis Of Near-infrared Iridium(Ⅲ)Complex-based Phosphorescent Probes And Their Application On The Luminescence Detection Of Active Molecules

Phosphorescent iridium complexes have many excellent properties,such as easy regulation of excitation and emission wavelengths,long luminescence lifetime,good photostability,large stokes shift and high luminescence quantum yield.Especially,NIR-emitting phosphorescent iridium complexes have the advantages of high penetration depth and low background fluorescence interference in bioimaging.In addition,active molecule refers to a small quantity of molecules that can greatly affect life activities;its concentration level is closely related to many physiological and pathological processes.Therefore,the development of NIR-emitting iridium complex phosphorescence probes with rapid,specific and sensitive detection of active molecules in vitro and in vivo has important research value.In this thesis,three novel NIR-emitting iridium complex phosphorescent probes were developed and successfully applied to the luminescence detection and imaging of cystine/homocysteine,peroxynitrite and phosgene.The main research contents are as follows:1.The application of NIR-emitting iridium(Ⅲ)complex phosphorescent probe FNO1 in the luminescence imaging detection of cysteine/homocysteineCysteine and homocysteine play an important role in maintaining the biological redox balance.Their abnormal levels in living bodies are associated with many diseases.Therefore,the detection and monitoring of their content levels in living samples can contribute to the understanding of their physiological functions and assessment of the diagnosis and treatment of related diseases.A novel NIR-emitting iridium complex phosphorescence probe FNO1 with high sensitivity was designed and synthesized for the luminescence detection of cysteine and homocysteine.The luminescence intensity of FNO1 increased by 44/52 times after it had responded with cysteine/homocysteine,so FNO1 is an enhanced-type luminescent probe.The probe has the advantages of good specificity,fast response speed and good photostability.The detection limits of FNO1 to cysteine and homocysteine were as low as 0.228μM and 0.134μM,indicating that the probe can be used for the detection of cysteine and homocysteine at low physiological concentrations.Importantly,the probe FNO1 has phosphorescence emission in the near-infrared region(650-830 nm),so it had been successfully applied in the luminescence imaging of cysteine and homocysteine in living cells,zebrafish and mice.2.The application of NIR-emitting iridium complex phosphorescent probe FNO2 in the time-resolved luminescence detection of peroxynitritePeroxynitrite(ONOO~-)has strong oxidation and nitrification ability,and excessive ONOO~-is related to inflammation,cardiovascular disease,rheumatoid arthritis and other diseases.Accordingly,a sensitive and specific probe for tracking ONOO~-in living bodies can be developed to better understand its related physiological functions.A novel NIR-emitting iridium complex phosphorescence probe FNO2 with high response speed luminescence detection of ONOO~-was designed and synthesized.The probe FNO2 fully responds to ONOO~-within seconds,indicating that the probe is suitable for the detection of short-lived ONOO~-in living bodies.The probe has the advantages of fast response,good specificity and low cytotoxicity.The luminescence lifetimes of probe FNO2 and its response products are 7.49μs and 7.14μs respectively.Thus,spontaneous background fluorescence in living bodies simulated by Rhodamine B can be effectively shielded by time-resolved luminescence detection technology.At last,probe FNO2 was successfully applied in the luminescence imaging of induced ONOO~-in tumor cells and mice.3.The application of NIR-emitting iridium(Ⅲ)complex phosphorescent probe FNO3 in rapid and convenient luminescence detection of phosgenePhosgene is a colorless and highly toxic gas;however,it is also an essential raw material in industrial production.The accidental leakage of phosgene poses a great threat to the safety of public life.Therefore,it is of great practical significance to develop a rapid and sensitive mean to monitor phosgene.A novel NIR-emitting phosphorescent iridium complex probe FNO3 with high sensitivity,high response speed and good specificity was designed and synthesized for real-time detection of phosgene.The titration experiments of UV-Vis absorption and emission spectra were carried out,and the results showed that the emission intensity of FNO3 decreased obviously even when it responed to 0.1 equivalent BTC.There was a good linear relationship between the logarithmic value of luminescence intensity of FNO3 and the concentration of BTC within the range of 0-1.2 equivalent(R~2=0.998),and the detection limit was as low as 0.18μM,which indicated that the probe could quantitatively detect phosgene at low concentration.Response mechanism of probe FNO3 to phosgene is that the recognition group oxime group on the auxiliary ligand will be converted to cyano group when it reacts with phosgene,and the electron absorption ability of cyano group is stronger than that of oxime group,which leads to the derease of the probe luminescence intensity.Importantly,the test strips prepared by the probe were successfully applied to the colorimetric luminescence detection of phosgene gas,showing the rapid and convenient detection performance of the probe FNO3 towards phosgene.