Synthesis, Structure Characterization And Luminescent Properties Of New Hydrazone Rare Earth Complexes

Organic electroluminescence has achieved significant penetration in the area of research owing to its fascinating characteristics and potential applications in flat panel displays. Among the large number of organic electroluminescence materials,acylhydrazone is a potential organic synthetic intermediate having novel and strong multidentate coordination structure and capability because of the co-existence of C=N and C=O bonds in the same molecule. The presence of more electronegative nitrogen and oxygen on acylhydrazones is capable of enhancing their coordination possibilities.Rare earth(RE) metal ions have special electronic structures and outstanding optical,electrical, and magnetic properties. Therefore, significant research efforts have been devoted to the complexes formed by RE metal ions with acylhydrazones. The acylhydrazone complexes of RE metal ions prepared after confirming the compatibility of acylhydrazones with RE metal ions exhibit pure fluorescent color, narrow bandwidth, and high quantum efficiency. This can remarkably modify and improve the original properties of the RE metal ions and ligands. These complexes have attracted progressive attention and they exhibit significant potential applications as organic electroluminescence materials.Influences of novel ligands, auxiliary ligands, and RE ions centers on the luminescent properties of the complexes were investigated based on the prospect of the RE metal ions and acylhydrazone in the field of organic electroluminescence. The organic RE complexes emitting various luminous colors were prepared successfully.Moreover, complexes with optimal luminous performance were doped with REcomplexes with excellent luminous properties.1-H2 L and 2-H2 L ligands were synthesized by esterification, hydrazine, Duff synthesis followed by Schiff base condensation using benzoic acid as raw material.The monocrystals of 2-H2 L ligand were cultured successfully for the first time by slow evaporation method. The corresponding experimental parameters of the monocrystals of 2-H2 L ligand were also investigated.Seven RE metal ions complexes containing salicylaldehyde benzoylhydrazone were synthesized. It was found that the general chemical formula of the complexes was Ln4(1-HL)8O2·8(H2O)(Ln = Y, Pr, Tb, Er, Dy, Sm, and Eu). The complexes were characterized by energy-dispersive X-ray spectroscopy(EDS), Fourier transform infrared(FTIR) spectroscopy, thermo gravimetric analysis(TGA), and ultraviolet(UV)spectroscopy.The Y4(HL)8O2·8(H2O) monocrystals were also successfully cultured. The X-ray diffraction(XRD) patterns indicated that the quad-core eight ligand symmetry structure of yttrium complexes corresponded to the tetragonal crystal system and P4/ncc space group, with which the molecule structures of these complexes were testified. Simultaneously, the characteristic spectra of the complexes obtained by photoluminescence(PL) spectroscopy were investigated in detail and the influences of types of metal ions and ligand structures on the fluorescence intensity were studied.Seven 2-H2 L ligand based complexes were synthesized, and their chemical formulas were characterized by EDS, FTIR spectroscopy, TGA, UV spectroscopy, and XRD. The results indicated that the general chemical formula of the 2-H2 L ligand based complexes was Ln(2-HL)2NO3·2(H2O)(Ln = Y, Pr, Tb, Er, Dy, Sm, and Eu).Simultaneously, the characteristic spectra of the complexes obtained by PL spectroscopy were investigated and the influences of types of metal ions and ligand structures on the fluorescence intensity were investigated.Twenty RE metal ions doped complexes were synthesized by reaction of 1-H2 L and 2-H2 L ligands with terbium and transition metals(Zn and Ni), respectively, in ethanol. The results of the EDS and RE complexometric titration indicated that the general chemical formula of the complexes was Tb1?xMx(HL)2?x·NO3·2H2O(x = 0.20,0.40, 0.60, 0.80, 1.0.M=Zn,Ni). The variation in the ratios of the RE metal ions led tothe generation of the most cost-effective fluorescent material exhibiting the best performance. Finally, this study provides a new perspective to the understanding of the acylhydrazone complexes of the RE metal ions acting as potential candidates for the electroluminescence applications based on their photoluminescence properties.