Dendrimers With Luminescent Materials

Dendrimers have received particular attentions for their specific structural properties and becomes the pop-field of the supermolecular chemistry. Design and synthesis of new kinds of dendrimers and the study of their photoelectricity properties becomes the most important part of the fields. The contents are as follows (Please see the attached table for the molecular structure fromular of the materials synthezied in this thesis.) :1. Polyarylether dendrimer with the core of terbium(III) complex. Using convergent procedure, a series of novel dendritic β-diketone ligands 1-phenyl-3-[G-n]-4-phenylacetyl-5-pyrazolone (n = 0-3, G stands for poly aryl ether) were synthesized by introducing Frenchet type dendritic branches. The dendritic Tb-complexes were characterized successfully by FT-IR spectroscopy, ESI mass spectra and elemental analysis, and Tb(LG-0)₃(EtOH)(H₂O) and Tb(LG-1)₃(H₂O)₂ were characterized by X-ray crystallography. The photophysical studies indicated that the dendritic complexes in solution exhibited the enhancement of both luminescence quantum yield and luminescence lifetime with the increasing of dendron generation. By measuring the efficiency of the terbium emission (ΦTb) and the energy transfer(Φ_transfer) from the ligand to Tb³⁺ using the method based on resonance energy transfer, we found that the Φ_transfer increased with the increasing of the dendron generation, which confirmed the shell effect and increased antenna effect on the fluorescent emission for the dendritic terbium complexes Tb(LG-n)₃.2. Synthesis and electroluminescent (EL) properties of red phosphorescent Iridium cored dendrimers. One type of dendritic β-diketone ligands 1-phenyl-3-[G-n]-4-phenylacetyl-5-pyrazolone (LG-n, n = 0-3) were designed and synthesized. Furthermore, their iridium complexes(2-tpq)₂Ir(LG-n) (2-tpq stands for 2-thiophenon quinoline) were synthesized and characterized by ¹H NMR, MALDI-TOF mass spectra and elemental analysis, and (2-tpq)₂Ir(LG-0) and (2-tpq)₂-Ir(LG-l) were characterized by X-ray crystallography. Their photophysical, electrochemical and electrophosphorescent properties were investigated in detail. The phosphorescent luminescence spectra of film and solution of (2-tpq)₂Ir(LG-3) are similar, indicating that the high generation ligand reduced the interaction of the iridium(III) complex molecules. Furthermore, little difference between the intrinsic and measured lifetime was observed even at high concentrations, and the quenching rate constant k_qwas apparently below the diffusion-controlled limit of 10¹⁰mol^-1S^-1,suggesting that very weak concentration quenching exists in (2-tpq)₂Ir(LG-3) solution. The polymer-based electrophosphorescent devices were fabricated by using (2-tpq)₂Ir(LG-n) complex with various doping concentrations. For (2-tpq)₂Ir(LG-2) and (2-tpq)₂Ir(LG-3), the high device efficiencies were obtained using high doping concentrations. The best device by doping 15 wt.-% (2-tpq)₂Ir(LG-3) showed good EL properties with turn-on voltages of 6.7 V, peak brightness of 2673 cd/m2 and high external quantum efficiency of 8.0%.Moreover, a series of novel dendrictic C^N ligand (Gn-nqp) and their iridium complexes (Gn-nqp)₂Ir(acac) were synthesized and characterized by ¹H NMR, MALDI-TOF mass spectra and elemental analysis. Their photophysical, electrochemical and electrophosphorescence properties were investigated. The dendritic complexes exhibited enhanced luminescence quantum yield and luminescence lifetime with the increasing of dendron generation. The dendritic complexes with the peripheral group of naphthalene also showed high luminescence quantum yield. (NG-2-nqp)₂Ir(acac) was used as an efficient dopant for fabricating nearly saturated red polymer light-emitting diode, and EL device gave high external quantum efficiency of 7.6% and peak brightness of 2488 cd/m2. 3. Study on the photophysical properties of small molecular complexes based on pyrazolone. A series of lanthanide (Tb³⁺, Eu³⁺, Sm³⁺, Gd³⁺, Dy³⁺) complexes with 1,3-diphenyl-4-phenylacetyl-5-pyrazolone were synthesized. The luminance properties of the lanthanide complexes were studied in detail. Importantly, the triplet energy level of the ligand was measured with reference to the phosphorescence spectrum of gadolinium complex, and the difference between the ligand's triplet energy level and the excited energy level of lanthanide ion results in different photoluminescence of the corresponding complex. An organic electroluminescence device was fabricated by using Tb(LG-0)₃(C₂H₅OH)(H₂O) as luminescent material, and it showed the highest luminance of 135 cd/m². A new β-diketone ligand 4-(3,5-bis(benzyloxy)benzoyl)-1,3-diphenyl-1 H-pyrazol-5(4H)-one(HBDPO) was designed and its iridium complex (tpq)₂Ir(BDPO) was synthesized. Red polymer-based electrophosphorescent device with high external quantum efficiency of 7.9% and peak brightnesses of 2717 cd/m² was fabricated by using (tpq)₂Ir(BDPO) as dopant.