Molecular Design Of Iridium Complex Functional Photoelectric Material And Its Application In Biochemical Analysis

Photoelectrochemical?PEC?analytical technique has revealed its tremendous potential for biological assays.PEC process is exactly the reverse of electrochemiluminescence?ECL?,which employing light as input and the transduced electrical signal as the detection readout.As an important branch of PEC active materials,metal organic complexes are known to be a remarkable species for PEC application because of their high thermal stability,appropriate redox and photophysical characters.To date,most of the PEC studies on metal-organic complexes merely focused on Ru?II?complexes,and Ru?bpy?₃²⁺and its derivatives-based PEC system have been extensively applied to detect DNA and immunoassay.The success of Ru?II?complexes as photoactive species for EC bioanalysis stimulates the search for other metal-based complexes.As typical metal-organic complexes,cyclometalated Ir?III?complexes have attracted a lot of attention over the past decades due to their enormous potential application in optoelectronic devices,such as organic light-emitting devices?OLEDs?,organic photovoltaics?OPVs?,photo-induced hydrogen?H₂?generation,and dye-sensitized solar cells?DSSCs?.Despite the rapid development,exploiting iridium?III?complex as photoactive species for PEC bioanalysis is just starting.Based on the above reasons,and Ir?III?complexes have the photochemical properties are greatly influenced by ligand,absorbing light range can control etc,and through the design of iridium complexes structure,by introducing a different ability to capture the light of the ligand,designed and synthesized two long wave direction has the very strong light absorption of Ir?III?complexes,at the same time the two iridium complexes as sensitization agent sensitizing Ni O and TiO2 photoelectric chemical enhancements.Based on the specific recognition of antigen and antibody and the molecular structure's sensitive response to H⁺,it is used for immunosensor analysis and photoelectric pH sensor.The main contents are as follows:1.Cyclometalated iridium?III?complex-sensitized Ni O photocathode for photoelectrochemical immunoassay.In this work,a iridium?III?complex,[Ir?C₆?₂?dcbpy?]⁺PF₆^-?dcbpy=2,2?-bipyridine-4,4?-dicarboxylic acid?was prepared,employing dcbpy was used as the auxiliary ligand,and the cyclometallated ligand coumarin-6?C6?was used as the main ligand.The UV-vis absorption spectrum,photoelectrochemical properties and electrochemical properties of this iridium complex were studied and used to sensitize Ni O thin films,which effectively improved the photoelectrochemical response signal and sensitized the iridium complex to NiO.The effect of photoelectric properties and possible photoelectric mechanisms were studied and to characterize the surface loading,UV-vis absorption spectrum,and photoelectric properties of the iridium complex-sensitized NiO thin film.Studies have shown that the designed and synthesized[Ir?C6?₂?dcbpy?]⁺PF₆^-has strong absorption in the visible range:the molar absorption coefficient at 480 nm is 43100 M-1cm-1,and the prepared[Ir?C6?₂?dcbpy?]⁺PF₆^-produces a cathode photocurrent of 200 nA/cm².After the iridium complex sensitized the Ni O film,the photocurrent signal was increased by27 times compared with the pure iridium complex.Based on the excellent sensitized Ni O effect of this complex,the[Ir?C6?₂?dcbpy?]⁺PF₆^-sensitized Ni O electrode was used as the photoelectric signal generating part of the PEC immunosensor,and the dye-sensitized NiO electrode was used as the base PEC immunosensor for sensitive detection of prostate specific antigen PSA.Studies have shown that due to the excellent PEC performance of the Ir?III?complex sensitized Ni O and the sensitive detection of PSA,the linear range is 1 pg/mL-10 ng/m L,the detection limit is as low as 240 fg/m L,and it has good specificity,selectivity and stability which shows The synthesized Ir?III?complex has good PEC performance and has great potential in PEC bioanalysis,which provides an excellent sensing platform for biochemical analysis and clinical diagnosis.2.Application of rhodamine B-ligand iridium complex molecular probe in photoelectric pH sensorIn this work,Using rhodamine B hydrazide derivatives as auxiliary ligands and3-?2-pyridine?benzoic acid?pba?containing-COOH groups as main ligands,Ir?III?complexes[Rh BIr?pba?₂]⁺PF₆^-were successfully designed and synthesized.And its photoelectrochemical properties were characterized by UV-vis absorption spectrum and photoelectrochemical methods,and it was combined with TiO₂ to improve the photocurrent signal through dye sensitization.Studies have shown that the complex has good light-capturing properties,and moves the absorption region of the iridium complex to around 590 nm,with a significant absorption peak at 560 nm,and a stable photocurrent response in the visible light region.After combining with TiO₂,a strong photocurrent enhancement is obtained,which improves the sensitivity of the sensor.The absorption of visible light at 560 nm was changed by the ring opening process of rhodamine B hydrazide to H⁺sensitive spiro.A PEC p H sensor platform based on[RhBIr?pba?₂]⁺PF₆^-sensitized Ti O₂ signal amplification and rhodamine B hydrazide H+induced ring opening was developed.The research shows that the constructed PEC pH sensor platform has shown good analytical performance in detecting p H,with a linear range of pH=2.5-8.0 and a linear correlation coefficient R2=0.9957.It shows that the PEC pH sensor has been successfully constructed and successfully detected the pH value,and has the advantages of convenient experiment,simple method,quick and sensitive,etc.,which has opened up new ideas for the pH sensor in the direction of photoelectrochemistry.