| Abstract
| - A new compound with the formula [Eu4(ETA)9(OH)3(H2O)3)], where ETA is ethyl 4,4,4-trifluoroacetoacetate,has been synthesized and investigated by photoluminescence spectroscopy. The compound was characterizedby means of chemical analysis, vibrational (IR), UV−vis absorption, and luminescence spectroscopies, andX-ray crystallography. The crystal structure of the [Eu4(ETA)9(OH)3(H2O)3)] complex in the solid state,determined by X-ray diffraction analysis, revealed that it crystallizes in the triclinic crystal system, spacegroup P1̄, with four crystallographically independent europium centers. From these structural data, the ground-state geometry of the tetramer has been calculated by using the Sparkle/AM1 model. The emission spectrumshows the characteristic transitions of the Eu3+ ion. The features displayed by the5D0 → 7F0 transition in theemission spectrum are consistent with the Eu3+ ion occupying four different sites in chemical environmentsof low symmetries, in agreement with the X-ray data and the optimized geometry obtained from the Sparkle/AM1 model. These structural results have allowed the theoretical calculation of 4f−4f intensity parameters,including the forced electric dipole and dynamic coupling mechanisms as well as ligand singlet and tripletstates, in good agreement with experiment.
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