Luminescence efficiency of aromatic carboxylates of europium and terbium when methylene bridges and nitro groups are present in the ligands |
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Authors: | V I Tsaryuk K P Zhuravlev V F Zolin V A Kudryashova J Legendziewicz R Szostak |
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Institution: | (1) Institute of Radioengineering and Electronics, Russian Academy of Sciences, 1 pl. Vvedenskogo, Fryazino, Moscow Oblast, 141190;(2) Chemistry Department, Wroclaw University, Poland |
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Abstract: | We discuss the possibility of optimizing the brightness of luminescence for phenylcarboxylates, naphthylcarboxylates, and
indolylcarboxylates of europium and terbium and their adducts with 1,10-phenanthroline and 2,2′-bipyridine by modifying the
ligands. We have studied the efficiency of luminescence and luminescence excitation. We consider the effect of blocking energy
transfer from the ligands to the Eu3+ and Tb3+ ions by methylene (-CH2-) bridges dividing the π-electron system of the ligands into two parts and by the electronacceptor nitro group (-NO2). We have analyzed the pathways for transfer and degradation of the excitation energy at 77 K and 300 K. From the phosphorescence
spectra of gadolinium salts, we have determined the energies of the lowest excited triplet states of the ligands. We consider
the effect of the relative positions of the triplet levels of the ligands and the excited levels of the Eu3+ and Tb3+ ions on the luminescence efficiency. We found channels for dissipation of the excitation energy via the ππ* and nπ* states
of the aromatic system of the carboxylate and the NO2 group.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 1, pp. 48–54, January–February, 2007. |
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Keywords: | Eu3+ ion Tb3+ ion luminescence and luminescence excitation spectra luminescence efficiency aromatic carboxylates |
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