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Synthesis and Luminescent Properties of Novel Europium( III ) Heterocyclic β‐Diketone Complexes with Lewis Bases: Structural Analysis Using the Sparkle/AM1 Model
Author(s) -
Pavithran Rani,
Reddy M. L. P.,
Junior Severino A.,
Freire Ricardo O.,
Rocha Gerd B.,
Lima Patricia P.
Publication year - 2005
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200500461
Subject(s) - chemistry , lanthanide , europium , ligand (biochemistry) , luminescence , adduct , photoluminescence , intramolecular force , excited state , crystallography , stereochemistry , organic chemistry , ion , biochemistry , physics , receptor , optoelectronics , optics , nuclear physics
Tris(β‐diketonato)europium( III ) complexes of general formula [Eu(TPI) 3 · L], with chelating ligands such as 3‐phenyl‐4‐(4‐toluoyl)‐5‐isoxazolone (HTPI) and adduct‐forming reagents [L = H 2 O, tri‐ n ‐octylphosphane oxide (TOPO), triphenylphosphane oxide (TPhPO), 1,10‐phenanthroline], have been synthesized and characterized by elemental analysis and FT‐IR, 1 H NMR, and photoluminescence spectroscopy. The coordination geometries of the complexes were calculated using the Sparkle/AM1 (Sparkle model for the calculation of lanthanide complexes within the Austin model 1) model. The ligand–Eu 3+ energy‐transfer rates were calculated using a model of intramolecular energy transfer in lanthanide coordination complexes reported in the literature. The room‐temperature PL spectra of the europium( III ) complexes are composed of the typical Eu 3+ red emission, assigned to transitions between the first excited state ( 5 D 0 ) and the multiplet ( 7 F 0–4 ). The results clearly show that the substitution of water molecules by TOPO leads to greatly enhanced quantum yields (i.e., 1.3 % vs. 49.5 %) and longer 5 D 0 lifetimes (220 vs. 980 μs). This can be ascribed to a more efficient ligand‐to‐metal energy transfer and a less efficient nonradiative 5 D 0 relaxation process. The theoretical quantum yields are in good agreement with the experimental quantum yields, which highlights that the present theoretical approach can be a powerful tool for the a priori design of highly luminescent lanthanide complexes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)