Synthesis Of Photoelectronic Materials Iridium Complex And Their Application In Biochemical Analysis

Photoelectrochemical?PEC?analysis approach is an analytical method,which is based on the development of photoelectric phenomenon.In the process of PEC analysis,the excitation and detection process is carried out step-by-step,and the detection current signal with small background interference,so it has become a great potential analytical method for the application.At present,the photoelectrochemical analysis approach is mainly engaged in the research range of semiconductor photochromics,such as TiO₂ nanoparticles or quantum dots and cyclometalated Ru???complexes,but the research on cyclometalated iridium complexes is relatively few.As a photoelectric active material,cyclometalated iridium complexes has great significance in PEC analysis due to its high quantum yield,long phosphorescence lifetime,stable redox properties and photoelectrochemical properties.In this paper,we synthesized two novel ionic iridium complexes by designing different ligands,studied their PEC properties and applied two kinds of iridium complexes to biochemical sensors.This thesis consists of three parts:First,the recent advances in photoelectrochemical analysis and the application of photoelectric sensors were reviewed.We introduced the principle of PEC analysis and several common photoelectrochemical active substances including semiconductor nanomaterials,organic photoelectric materials,metal composites,nanocomposites,etc.;and then we introduced the application of PEC sensors in the biochemical analysis as well as the development trend and prospect of photoelectrochemical analysis.Second,we synthesized a label-free ionic cyclometalated iridium complexes [?ppy?₂Ir?dppz?]PF₆ and characterized its structure by NMR.we also studied the UV-vis spectra,fluorescence spectra,electrochemical properties,and photoelectrochemical properties of this substance.As proven by our research,at the illumination of 380 nm,it exhibited a stable cathodic photocurrent in the presence of O₂ as an electron acceptor,and a stable oxidation current is generated when an electron donor?such as TEOA?is present.When the TEOA concentration is 0.1 mol/L,the bias voltage is 0.1 V,the photocurrent response is the best,and the dark current effect is small.DNA is an important carrier of life genetic information,it has the function of storing and transmitting information,so the study on the function of DNA is of great significance in modern life sciences and medical research.Based on the principle of HCR signal amplification and the photoelectric properties of [?ppy?₂Ir?dppz?]⁺,we constructed a photoelectrochemical biosensor to detect DNA,where [?ppy?₂Ir?dppz?]⁺ as an embedded signal molecule.This proposed method exhibits good selectivity,good reproducibility and high sensitivity,this label-free detection approach is also has low detection limit,the detection limit of 9 × 10-15 mol/L.The last,we synthesized another cyclometalated Iridium complex [Ir?C₆?₂?dcbpy?]PF₆,which based on iridium-6 as the main ligand and 2,2'-bipyridyl-4,4'-dicarboxylic acid as the ancillary ligand.And its structure was characterized by NMR.The UV-vis,fluorescence spectra,electrochemical properties and PEC properties were examined.The results show that [Ir?C₆?₂?dcbpy?]⁺ has a strong light absorption at 470 nm.when illuminated by the light of 470 nm,if in the presence of electron donors,a stable oxidation current is generated.When an electron acceptor is present,stable reduction current is generated.And when the ascorbic acid concentration is 0.1 mol/L,bias voltage is 0.1 V,the photoelectric signal was the best.Thrombin is a kind of serine protease with promote blood coagulating,which can specifically recognizes a DNA sequence and has a strong affinity to a specific sequence of DNA,whereas in the presence of thrombin,thrombin promote the structure of aptamer from a loose state into a G-quadruplex structure so that the structure of ds-DNA were destroyed.we designed a photoelectrochemical sensor according to the characteristics of thrombin and the photoelectrochemical properties of [Ir?C₆?₂?dcbpy?]⁺ to the detect the thrombin,and its detection limit was 1.64×10-13 mol/L.