Synthesis,Characterization, And Photophysical Properties Of Eu(Ⅲ) And Tb (Ⅲ) Complexes Based On β-diketonate With Triphenylamine And Carbazole Moieties

Abstract:Triphenylamine, carbazoles and their derivatives owning high charge mobility, light-harvesting unit, high thermal stability and low optical absorption in the visible region are often acted as the hole-transporting materials for OLEDs. In this paper, we designed and synthesized three new β-diketonate ligands with triphenylamine and carbazole moieties, namely,1-(4-Diphenylamino-phenyl)-3-{6-[3-(4-diphenylamino-phenyl)-3-oxo-propionyl]-pyridin-2-yl}-propane-1,3-dion e(L1),1-(4-diphenylamino-phenyl)-3-(9-ethyl-9H-carbazol-3-yl)-propane-1,3-dione(L2),1-(1,5-Diphenyl-1H-pyrazol-3-yl)-3-(9-ethyl-9H-fluoren-3-yl)-propane-1,3-dione(L3). Ligand L1contains electron donors-conjugate system-electron acceptor β-diketone structure, namely D-Π-A structure; Ligand L2simultaneously contains carbazole and triphenylamine groups namely D-Π-D structure; Two kinds of structure have good thermal stability and optical properties, which expected to achieve a relatively balanced charge injection, and possessing high efficiency, long lifetime and high photochemical stability under UV irradiation. Based on the above considerations, corresponding Eu(Ⅲ) and Tb(Ⅲ) complexes of Ligand L1and L2, using1,10-phenanthroline as the second ligand were prepared and characterized by elemental analysis, IR spectra, and1H NMR.We studied the photoluminescence spectra, quantum efficiency and the fluorescence lifetime of the complexes Eu2(L1)3(phen)2、 Tb2(L1)3(phen)2、Eu(L2)3(phen)、and Tb(L2)3(phen). The photoluminescence spectra indicate that the ligand L、L2has excellent antenna effect to sensitize the lanthanide ions while using quinine sulfate solution as reference sample, the quantum efficiency of the complexes Eu2(L,)3(phen)2and Eu(L2)3(phen) are26.7%and15.7%in the CHC13solution at room temperature, respectively. The fluorescence lifetime of the complexes Eu2(L1)3(phen)2and Eu(L2)3(phen) are529.73μs and 397.53μs, respectively. The thermogravimetric analysis show the complexes Eu2(L1)3(phen)2and Eu(L2)3(phen) have good thermal stabilities with decomposition temperatures312-602℃and356-665℃respectively. They may be provided with potential applications in organic electroluminescent materials.