A study of the fluorescence of some newly synthesized europium complexes with pyrazolone derivatives

• Published in: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Molecular and biomolecular spectroscopy, 2000-12, Vol.56 (14), p.2645-2651
• Main Authors: Qian, Dong-Jin, Leng, Wei-Nan, Zhang, Yuan, Chen, Zhong, Van Houten, J
• Format: Article
• Language: English
• Subjects: Europium - chemistry; Europium complexes; Fluorescence; Lifetime; Pyrazoles - chemistry; Pyrazolones; Spectrometry, Fluorescence - methods; Spectrophotometry, Ultraviolet; Synthesis
• ISSN: 1386-1425
• DOI: 10.1016/S1386-1425(00)00306-1

Some europium complexes with pyrazolone derivatives and 1,10-phenanthroline were synthesized and characterized. The europium ion was found to coordinate to O atoms of the pyrazolone derivatives and to N atoms of 1,10-phenanthroline. A strongly ligand-localized UV absorption leads to the europium-centered emissions between 580 and 750 nm which were assigned as the 5D 0 → 7F 0,1,2,3,4 and 5D 1 → 7F 3,4 transitions. A low site symmetry for the Eu 3+ ion was confirmed from the observation of 5D 0 → 7F 0 emission and from the splitting of the other bands. In contrast to many Eu complexes that have been investigated a rather weak emission was measured by introduction of a Schiff base to form a ternary complex with the pyrazolone derivative. The long fluorescence lifetimes of these complexes suggest an energy transfer process from ligands to Eu 3+ ion through the triplet state of the ligands.