Synthesis And Application Research Of Highly Phosphorescent Metal Iridium Complexes

Electrophosphorescent materials incorporating complexes of heavy metals have attracted great attention due to the potential application of these complexes as highly efficient electroluminescent(EL)emitters.In all of these,iridium complexes are the most effective.In this thesis,basing on molecular designs,3 colors of heavy metal iridium incorporating complexes have been designed and synthesized.1.Green emitting materialThe heavy metal iridium incorporating complex,(MDPP)₂Ir(acac),was synthesized by reaction of 5-methyl-2,3-diphenylpyrazine(MDPP)with iridium trichloride hydrate. The best synthesis method was studied.At first,2-methyl-2,3-dihydrgen-5,6-diphenylpyrazine was synthesized by refluing benzil with 1.2 equiv of 1,2-diaminopropane in ethanol at 75℃～78℃for 3 h.Next,MDPP was prepared by reacting 2-methyl-2,3-dihydrgen-5,6-diphenylpyrazine with 1.2 equiv of tetrachloro-p-benzoquinone in xylene at 125℃～127℃for 1.5 h.Thirdly,(MDPP)₂Ir(μ-Cl)₂Ir(MDPP)₂ was synthesized by heating iridium trichloride hydrate to 94℃～98℃with 2.2 equiv of MDPP in a 3:1～1:1 mixture of 2-ethoxyethanol and deionized water for 9 h.Finally, (MDPP)₂Ir(acac)was prepared by reacting(MDPP)₂Ir(μ-Cl)₂Ir(MDPP)₂ with 2.2 equiv of acetylacetone and an equivalalent amount of K₂CO₃ in 2-ethoxyethanol at 106℃～110℃for 21 h.The HPLC purities of iridium complex was 96.7%.2.Red emitting materials(DBQ)₂Ir(acac)and(MDQ)₂Ir(acac)were synthesized by reaction of dibenzo[f,h]-quinoxaline (DBQ)or 2-methyldibenzo[f,h]quinoxaline(MDQ)with iridium trichloride hydrate.The best synthesis condition was studied.Firstly,DBQ(MDQ)was synthesized by refluing 9,10-phenanthrenequinone with 1.2 equiv of diaminoethanol(1,2-diaminopropane) in ethanol at for 6 h(6 h).Secondly,(DBQ)₂Ir(μ-Cl)₂Ir(DBQ)₂((MDQ)₂Ir(μ-Cl)₂Ir(MDQ)₂)was synthesized by heating iridium trichloride hydrate to 96℃～98℃with 2.2 equiv of DBQ(MDQ)in a 3:1～1:1 mixture of 2-ethoxyethanol and deionized water for 9 h(9 h).At last,(DBQ)₂Ir(acac)((MDQ)₂Ir(acac))was prepared by reacting (DBQ)₂Ir(μ-Cl)₂Ir(DBQ)₂((MDQ)₂Ir(μ-Cl)₂Ir(MDQ)₂)with 2.2 equiv of acetylacetone and an equivalalent amount of K₂CO₃ in 2-ethoxyethanol at 112℃～115℃for 25 h(4 h).The HPLC purities of iridium complex were 95.6%and 94.6%.3.Blue emitting materialFIrpic was synthesized by reaction of 2-(4,6-difluorophenyl)pyridine(f₂ppy)with iridium trichloride hydrate.The best synthesis method was studied.Firstly,f₂ppy was synthesized by heating 2-bromopyridine with 2,4-difluorophenylbronic acid in a 2:1:2 mixture of toluene,ethanol and 2 M-sodium carbonate aqueous solution.Next,(f₂ppy)₂Ir(μ-Cl)₂Ir(f₂ppy)₂ was synthesized by heating iridium trichloride hydrate to 86℃～90℃with 2.2 equiv of f₂ppy in a 3:1～1:1 mixture of 2-ethoxyethanol and deionized water for 21 h.Finally,FIrpic was prepared by reacting(f₂ppy)₂Ir(μ-Cl)₂Ir(f₂ppy)₂ with 2.2 equiv of 2-picolinic acid and an equivalalent amount of K₂CO₃ in 1,2-dichloroethane at 74℃～78℃for 12 h～14 h.The HPLC purities of iridium complex was 99.4%.Their molecular structures were characterized by Hydrogen Nuclear Magnetic Resonance(¹HNMR)and Gas Chromatography-Mass(GC-MS)Spectrometry.Their photochemical and electrochemical properties were studied by Ultraviolet visible(UVvis) absorption spectrum,photoluminescence(PL)spectrum and Cyclic Voltammetry (CV).Their thermal properties were reseached by Differential Scanning Calorimeter (DSC).The results suggested that the obtained compounds had good thermal stabilities, photochemical and electrochemical properties,which can be served as the electrophosphorescent materials in the OLEDs.