Synthesis And Detection Applications Of Iridium (Ⅲ) Complex Phosphorescent Probe

Luminescent probes have been widely applied in food safety,environmental monitoring,bioanalysis,medical diagnosis,disease treatment,and so on,due to their low cost,easy synthesis,simple operation,real-time mode,etc.Luminescent probes are mainly composed of luminophore,linking unit and recognition group.Among them,the recognition group determines sensing behaviors of probes to the analytes.Iridium（Ⅲ）complex phosphorescent probes have the advantages of high photostability,large Stokes shift,long phosphorescent lifetime,and improved biocompatibility upon the conjugation to a functional peptide.Therefore,iridium complex phosphorescent probes have attracted much attention in environmental analysis and disease diagnosis.Hence,the development of novel iridium（Ⅲ）complex phosphorescent probes,and it is of great innovative significance and application and apply it to the detection of several important substances and diseases.This paper designs three functional recognition probes,the detection of boron trifluoride,dithiocarbamates,and prostate-specific membrane antigen were realized respectively based on these probes.The details are shown as follows:（1）A near-infrared iridium（Ⅲ）complex probe was designed based on2-（1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl）phenol as the recognition group and 6,7-difluoro-2-methyl-3-phenylquinoxaline as cyclometalated ligand,which realized the detection of boron trifluoride in solution.The recognition group was used to chelate boron trifluoride,while chelation can significantly increase the phosphorescence intensity of the probe at 650 nm.Meanwhile,it is found the intensity of the peak at around 475 nm is almost unchanged,achieving the analysis of boron trifluoride in a ratiometric mode.The probe at I_{650 nm}/I_{475 nm}showed a good linear relationship with the concentration of boron trifluoride in the range of 0-20μM and 30-80μM.The detection limit of the probe reaches as low as 0.35μM,and the detection time is only5 s.The probe has strong anti-interference and good detection response to boron trifluoride under the condition of being spiked by 5%organic waste solution.Furthermore,the signal of the probe can be distinguished from the traditional organic dye,Rhodamine 6G,by a time-resolved technology,showing an excellent application prospect.（2）A solvento type of iridium（Ⅲ）complex phosphorescent probe（solvento type of complex indicated directly coordinated of iridium center and solvento type of ligand）was designed and successfully used for the detection of dithiocarbamates.As the coordination between iridium（Ⅲ）metal center and acetonitrile ligand is weak,the solvent ligands of the iridium（Ⅲ）probe were easily replaced by dithiocarbamate derivatives.Based on this strategy,the selective phosphorescence detection of sodium diethyldithiocarbamate,sodium diethyldithiocarbamate,and ammonium pyrrolidine dithiocarbamate were realized in HEPES buffer.The probe shows a good detection relationship in the range of 0.50-20μM,0.50-40μM,and 2-12μM for these three species,respectively,and their limit of detection are as low as 0.33μM,0.15μM,0.10μM.This probe not only shows high selectivity to dithiocarbamates over metal ions,amino acids,glutathione,bovine serum albumin,and other common carbamates but also has good sensing performance in Xi’an moat water and food samples.Furthermore,this probe is capable of imaging dithiocarbamates in mitochondria.To our knowledge,this is the first probe for imaging dithiocarbamates in living cells.（3）Based on the recognition function of lysine-urea-glutamic acid（Lys-urea-Glu）to prostate-specific membrane antigen on prostate cancer cells,Lys-urea-Glu was connected to an iridium（Ⅲ）complex with 6,7-difluoro-2-methyl-3-phenylquinoxline as cyclometalated ligand,establishing a bioimaging probe for prostate cancer.The probe is not only capable of specific luminescence imaging of highly prostate-specific membrane antigen-expressing LNCa P cells but also achieved wash-free,near-infrared and cell-impermeable imaging.This probe is highly sensitive and selectivity,and its signal is highly associated with the expression levels of prostate-specific membrane antigen in prostate cells.Moreover,the probe belongs to the switch-on phosphorescent probe,which can effectively reduce the interference of background signals.The mechanism of its switch-on phosphorescence behavior is derived from the fact the binding between the probe and prostate-specific membrane antigen will restrict the rotation of the probe,while the probe will locate in a more hydrophobic environment,resulting in a stronger luminescence.Furthermore,the probe displays excellent imaging performance in a 3D prostate cancer cell model.