Modeling Lanthanide Complexes: Towards the Theoretical Design of Light Conversion Molecular Devices |
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Authors: | De Andrade Antônio V M Da Costa Nivan B Longo Ricardo L Malta Oscar L Simas Alfredo M De Sá Gilberto F |
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Institution: | (1) Departamento de Engenharia Química, Universidade Federal de Pernambuco, 50670-901 Recife, PE, Brazil;(2) Departamento de Química Fundamental, CCEN, UFPE, o[50670-901, Recife, PE, Brazil |
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Abstract: | Theoretical techniques have been developed and/or improved to predict the molecular structure of lanthanide complexes which
were used to calculate their electronic properties, in particular, their electronic spectra and energy levels necessary to
calculate the rates of energy transfer from the ligands to the metal ion. The molecular structure has been obtained by the
SMLC/AM1 (Sparkle Model for the Calculation of Lanthanide Complexes – Austin Model 1) model where the lanthanide ion is simulated
by a sparkle implemented into the AM1 Hamiltonian used to perform a HF-SCF (Hartree-Fock Self-Consistent Field) calculation.
The previous implementation of the SMLC/AM1 model (sparkle/1) involving only two parameters has been generalized to be consistent
with the AM1 Hamiltonian and the new model (sparkle/2) significantly improved the prediction of molecular structures of Eu(III)
complexes. For the electronic spectra and energy level calculations of the lanthanide complexes the model replaces the metal
ion by a point charge with the ligands held in their positions as determined by the SMLC/AM1 model, and uses a INDO/S-CI (intermediate
neglect of differential overlap/spectroscopic-configuration interaction) model. A preliminary study of the solvent effects
on the absorption spectra of the free ligand is also presented. For the ligand-lanthanide ion energy transfer Fermi's golden
rule is used with the multipolar and exchange mechanisms being implemented and tested for several complexes. These theoretical
techniques have been applied to several complexes yielding very good results when compared to experimental data as well as
predictions for the molecular and electronic structures and the relative contributions of the mechanisms for the energy transfer
rates.
This revised version was published online in June 2006 with corrections to the Cover Date. |
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Keywords: | Sparkle model lanthanide complexes INDO/S-CI energy transfer luminescence |
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