Theoretical and experimental photophysical studies of the tris(4,4,4-trifluoro-1-(1-naphthyl)-1,3-butanedionate) (2,2′-bipiridyl)-europium(III)

Abstract

The complexes tris(4,4,4-Trifluoro-1-(1-naphthyl)-1,3-butanedionate) (2,2 0 -bipiridyl) Ln(III), Ln(tan) 3 bipy, where Ln(III) ¼ Eu 3+ and Gd 3+ have been synthesized, characterized and their photophysical properties (absorption, excitation and luminescence spectra and emission quantum yield) investigated down to 4.2 K. The Eu(tan) 3 bipy complex has its molecular structure experimentally determined using X-ray crystallography and theoretically using the SMLC/AM1 method as well as their electronic singlet and triplet states were calculated, using the INDO/S-CI method with a point charge model to represent the Eu 3+ ion, where two values were adopted, +3.0e and +3.5e, to investigate the imperfect shielding of the 4f shells. The so calculated +3.5e model electronic absorption spectrum and low lying triplet state energies agreed very well with the experimental ones. The emission quantum yield of the Eu 3+ complex is quite low at room temperature, namely 7%, probably due to the too low lying triplet state, 19,050 cm -1 , and increases by a factor of three when the temperature is lowered to 4.2 K. This strong thermal effect indicates the presence of a channel deactivating the main emitting state, what can be due to a LMCT state possibly lying in the same spectral region, as usually found in Eu 3+ compounds.r 2005 Elsevier B.V. All rights reserved.

Comparison of optical properties of tris(4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedionato)europium(III) single crystals with dipyridyl and phenanthroline

“…The excitation spectra of the systems under investigation clearly confirm a more efficient emission of crystal (2). Because the two structural isomeric forms of Eu(TAN) 3 dipy have been investigated and reported [6,7], we also assumed two isomers in the sample with phenanthroline. This assumption was also supported by the fact that the crystals under study were very sensitive on energy of excitation.…”

“…However, only the block form exists without contamination of the second phase. The optical behaviour of Eu(TAN) 3 dipy single crystals in form of blocks was investigated in detail by Donega and co-workers [7]. In order to compare the photoemission behaviour of the two …”

“…Several of these complexes exist in crystal structure at least two slightly different coordination polyhedra [6]. Donega and Thompson reported the synthesis, X-ray and some photophysical studies and molecular and electronic structure of the lanthanide complexes Ln(TAN) 3 dipy (Ln = Eu, Gd) with emphasis on the ligand-centered triplet energy level [7]. The aim of our work is the comparison of the spectroscopic properties of Eu(TAN) 3 dipy and Eu(TAN) 3 phen, as well as the discussion the influence of the character of the second ligand on the excited state dynamics.…”

Recent advances in lanthanide spectroscopy in Brazil

“…Other investigations reporting the use and/or development of theoretical models or methodologies have been discussed in the literature [8,12,13,15,17,28,43,55,56,86,[199][200][201][202][203][204][205][206][207].…”

Synthesis and Spectral Characterization of Praseodymium(III) Complex with New Amino Acid-Based Azo Dye

“…In the last decade, the new materials based on lanthanide complexes have been studied with particular interest for applications as highly efficient light conversion molecular devices. They can be used in wide range of processes and new technologies, such as fluorescent lighting, electroluminescence color displays, luminescent labels in bioaffinity assays, bioinorganic sensors, and high technology optics and optoelectronic applications [2][3][4][5][6][7][8]. Weissman in 1942 reported that lanthanide can be improved by using an intramolecular energy transfer, the antenna effect [1].…”