Study on Synthesis and Fluorescence Characterization of Europium and Terbium Complexes of 1-(5-(2-Hydroxyphenyl)-3-Methyl-4,5- Dihydropyrazol-1-yl) Ethanone
Abstract：Six solid complexes(TbL3·2H2O, TbL2(phen)·H2O, TbL2(TPPO), EuL3·2H2O, EuL2(phen)·2H2O and EuL2(TPPO)·2H2O) have been synthesized based on the pyrazole ligand(HL)(phen=1,10-phenanthroline, TPPO=Tri-phenylphosphine oxide, HL=1-(5-(2-hydroxyphenyl)-3-methyl-4,5-dihydropyrazol-1-yl)ethanone). These complexes were characterized by elemental analysis, IR spectra, and fluorescence spectra. The IR spectra indicated that all complexes exhibited the characteristic peaks of asymmetric stretching vibration νCO and symmetric stretching vibration νCN peaks. The CO stretching band at 1 644 cm-1 of HL molecule shifted to lower band in the complexes. The O—H band at 3 072 of the HL lignd is also shifted to lower band. All these shifts indicated that carbonyl group, O—H and CN take part in coordinating with the rare-earth ion in the form of bridging tridentate. The excitation and emission spectra of the six complexes were determined at room temperature and the results show that EuL2(Phen)·2H2O and TbL2(Phen)·2H2O display the strongest relative fluorescence intensity with the excited bands at 310 and 320 nm, respectively. Meanwhile, the emission intensities of Eu3+and Tb3+ complexes were greatly sensitized by phen.
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