Novel highly luminescent europium dinitrosalicylates
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- 作者：K. Zhuravlev ; V. Tsaryuk ; J. Legendziewicz ; V. Kudryashova ; P. Gawryszewska ; V. Zolin
- 关键词：Eu3+ ; Dinitrosalicylate ; Luminescence ; Phosphorescence ; Excitation spectra ; Vibrational spectra ; Hydrogen bonds
- 刊名：Optical Materials
- 出版年：2009
- 出版时间：October 2009
- 年：2009
- 卷：31
- 期：12
- 页码：1822-1824
- 全文大小：343 K
文摘
A series of lanthanide dinitrosalicylates M3Ln(3,5-NO2-Sal)3 · nH2O (Ln = Eu, Gd; M = Li, Na, K, Cs) was synthesized. It was found that the luminescence efficiency of some M3Eu(3,5-NO2-Sal)3 · nH2O compounds was near to the high efficiency of europium dibenzoylmethanate with 1,10-phenanthroline, Eu(DBM)3 · Phen. The luminescence excitation spectra, electron-vibrational luminescence spectra, and vibrational IR spectra were investigated. The energy of the lowest excited triplet state of the ligand was obtained from phosphorescence spectra of M3Gd(3,5-NO2-Sal)3 · nH2O, M(3,5-NO2-HSal) · nH2O, and M2(3,5-NO2-Sal) · nH2O. The details of the structure of compounds were discussed. The influence of different M-cations on the Eu3+ luminescence efficiency and on the processes of excitation energy transfer to a Eu3+ ion was analyzed. The presence of large alkali metal cations in lanthanide dinitrosalicylates and an increase in the temperature weaken the network of hydrogen bonds and, to some extent, the “ligand–metal” bonds. This is a cause of a long-wavelength shift of the intraligand charge transfer (ILCT) band in Eu3+ excitation spectra arising at inclusion of Cs+ instead of Li+ cations in the crystal lattice and at the heating of compounds. A change of the energies of ligand electronic states at substitution of Li+ and Na+ for Cs+ can give a tenfold enhancement of the Eu3+ luminescence efficiency at 300 K.