Photophysical Properties Of Three Novel Organic Europium (Ⅲ) Complexes

The rare earth Polymer materials have attracted considerable interests in exploring luminous energy and materials. It have good luminescent characteristics and high color purity, and their organic compounds have advantage of low excited energy required, high fluorescence efficiency. However, the Eu-complexes still exist many problems such as poor stabillity, undefined internal luminescence mechansim and low electroluminescence efficiency, which restrict it applacations widely. Therefore, it is become essential to synthesis of novel luminescent materials and study luminescent properties of materials.The UV-Visible absorption and auto-fluorescence spectra of three novel Eu-complexes in the experiment are measured by the F_iber Optic Spectrometer system and Roper Scientific SP-2558 spectrometer, and analyzed theoretically and experimentally. It is found that:1. In the concentration range under our detection, the absorption spectra within 220³40nm are very strong. It gradually appear saturated absorption from shortwave to long wave area with the concentration increase, and stretch and broaden to long wave. At the solid state, the excitation wavelength is bathochromiced to 350nm. It is indicated that the complex absorption spectra and excitation spectra are mainly due to the Phenanthroline ligand.2. F_ive peaks of three novel Eu-complexes fluorescence spectra under different concentrations are all proper emission spectra of Eu3+, which are 580nm, 594nm, 613nm, 652nm and 701nm that is attributed to the5 D₀→7F₀, 5 D 0→7F₁, 5 D₀→7F₂, 5 D 0→7F₃ and 4705 D→F transitions of the Eu3+ respectively. The peak intensity ratio is: 2:6:32:1:2. The strongest peak was 613nm, the half width is about 5nm.3. The intensity ratioη=I613 / I594 has been utilized to discuss hypersensitivity and asymmetry of the Eu(III) complex The measured valuesηof the Eu-complexes is much larger than that (0.64) for the aqua Eu(III) ion, indicate changes in hypersensitivity and asymmetry of the Eu(III) complexes as a result of the influence of the Lx ligand and Phen co-ligands on the complex environments.4. The J-O theory of rare-earth crystal is studied the complex fluorescence mechansim successfully. And it is presented that the perturbation of the ligand change the parity state of Eu3+ energy field, result in increase of 613nm( 5 D₀→7F₂) and 701nm( 5 D₀→7F₄) transition probability. The peaks of 580nm and 652nm are due to J-Perturbation lead to state mixing effect between the generated.5. The UV-Visible absorption and auto-fluorescence spectra of three novel Eu-complexes indicate that there exist three potential energy transfer mechanism during the luminescence mechanism. It is the greatest of the probability energy absorbed transfer from the ligand phenanthroline to Eu3+.