Synthesis, Luminescence Properties And Applications For Cyclometaled Pt, Ir Complexes

The cyclometalated complexes have been widely applied in the felds ofanalitycal chemistry, biochemistry, catalysis and photoelectric technology due to theirinherent merits, such as high quantum efficiency, long luminescence lifetime, goodthermal stability and the emission spectral can be controlled by changing ligands.Among them, the development of cyclometalated platium and iridium complexes havegained extensive attention. Platium complexes have unique planar structure andiridium complexes have high quantum efficiency. What’s more, they can luminescephosphorescence at room temperature.This paper synthesized functional cyclometalated complexes centered on platiumand iridum, and investigated their photoelectrical properties and application inmolecular probe. This paper was divided into three parts:1. The introduction gives the characterisations of cyclometalated complexes,ligands forms systematically and points out their applications in phosphorescentmaterials, chemosensors and electrogenerated chemiluminescence(ECL).2. Two neutral cyclometalated platinum(II) complexes Pt(DPP)(acac) andPt(BPP)(acac) have been synthesized and characterized.2,4-diphenyl pyridine(DPP),2-(4-tertbutylbenzene)-4-phenyl pyridine (BPP) were taken as the ligands,acetylacetone(acac) as the auxiliary ligand. The photophysics, electrochemical andECL properties were investigated. The ECL potential of the two complexes werelocated at about0.75V vs. SCE and significantly shifted by about0.6V to the morenegative potential compared to the Ru(bpy)32+/TprA system. A lower redox potential ishelpful to decrease background interference. The ECL characteristics in the absence or presence TPrA in different solvents have also been invetigated. The result indicatedthe ECL intensity of complexes were affected by the polarity of solvents and TPrAwould enhance the ECL intensity significantly. The result that the quantum efficiencyof Pt(BPP)(acac) was similar to Ru(bpy)32+/TPrA, which was slight higher than that ofPt(DPP)(acac). What’s more, their electrochemical and ECL properties were verysimilar to those of Ru(bpy)32+/TPrA. This fact indicated that the synthesized Pt(ΙΙ)complexes can be a potential candidate as a new ECL luminophor to replace thetraditional Ru(bpy)32+system and be applied in many areas. In particular, it can beused to detect many bioactive substances in water phase.3. The Phenylboronic acid pinacol ester(bpe) moiety was introduced into3-(benzothiazol-2-yl)-7-hydroxyl-coumarin(Bthc) as cyclometalated ligand(Bthc-bpe)，acetylacetone(acac) as the auxiliary ligand. A new netural Ir(III) complexesphosphorescent probe(Ir-2) was designed and synthesized to be used for the detectionof hydrogen peroxide(H2O2). The photophysical properties of Ir-2were investigatedby UV-Vis absorption spectroscopy, phosphorescence emission spectroscopy andquantum efficiency calculations. The emission intensity decreased when Ir-2reactedwith H2O2, which can be explained by H2O2could cause the bpe moiety take off fromthe benzene and induce intermolecular aggregate. The result indicated Ir-2can be usedas a high selectively “ON-OFF” H2O2phosphorescent probe.