Uma metodologia para o projeto teórico de conversores moleculares de luz

Andrade, Antônio V.M. de; Costa, Nivan B. da; Simas, Alfredo M.; Longo, Ricardo L.; Malta, Oscar L.; Sá, Gilberto F. de

doi:10.1590/s0100-40421998000100009

Cited by 10 publications

(4 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Since the application of the SMLC/AM1 model for other systems was satisfactory [12,13,28], we have applied it to predict the geometry as well as the electronic absorption spectrum of the Eu(hfc) 3 ·bipyO 2 . Table 1 shows the Cartesian coordinates for the coordination polyhedron of the complex as determined by the sparkle model formed by the six bonding oxygen, from the three hfc and two oxygen from the bipyO 2 .…”

Section: Resultsmentioning

confidence: 99%

“…In this work, we present the synthesis, characterization, spectroscopic, and photophysical properties, theoretical and experimental, as well as the structure of the new Eu(hfc) 3 ·bipyO 2 complex (hfc: 6,6,7,7,8,8,8-heptafluoro-2,2 -dimethyl 1,3,5-hydroxymethyllene (+) canfore) (bipyO 2 : bipyridinedioxide). The sparkle model for lanthanide complexes within the AM1 approach (SMLC/AM1) [12,13], was used to calculate the geometry of this complex. From the determined geometry, the sparkle is replaced by a point charge +3e to account for the charge of the lanthanide ion.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Synthesis, sparkle model and spectroscopic studies of the Eu(hfc)3·bipyO2 complex

Mesquita¹,

Júnior²,

Silva³

et al. 2004

Journal of Alloys and Compounds

View full text Add to dashboard Cite

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Synthesis, sparkle model and spectroscopic studies of the Eu(hfc)3·bipyO2 complex

Mesquita¹,

Júnior²,

Silva³

et al. 2004

Journal of Alloys and Compounds

View full text Add to dashboard Cite

“…In our research group, the sparkle model has been applied in an intense way to calculate and predict some spectroscopic properties, such as singlet and triplet energy positions, electronic spectra of lanthanide complexes, etc. − With these quantities, we have built rate equations that involve energy transfer mechanisms to determine quantum yields and luminescence efficiencies for these complexes. In a recent paper, we presented a first proposition of a highly luminescent europium complex based on calculated results only.…”

Section: Introductionmentioning

confidence: 99%

Sparkle Model for AM1 Calculation of Lanthanide Complexes: Improved Parameters for Europium

et al. 2004

Self Cite

View full text Add to dashboard Cite

In the present work, we sought to improve our sparkle model for the calculation of lanthanide complexes, SMLC,in various ways: (i) inclusion of the europium atomic mass, (ii) reparametrization of the model within AM1 from a new response function including all distances of the coordination polyhedron for tris(acetylacetonate)(1,10-phenanthroline) europium(III), (iii) implementation of the model in the software package MOPAC93r2, and (iv) inclusion of spherical Gaussian functions in the expression which computes the core-core repulsion energy. The parametrization results indicate that SMLC II is superior to the previous version of the model because Gaussian functions proved essential if one requires a better description of the geometries of the complexes. In order to validate our parametrization, we carried out calculations on 96 europium(III) complexes, selected from Cambridge Structural Database 2003, and compared our predicted ground state geometries with the experimental ones. Our results show that this new parametrization of the SMLC model, with the inclusion of spherical Gaussian functions in the core-core repulsion energy, is better capable of predicting the Eu-ligand distances than the previous version. The unsigned mean error for all interatomic distances Eu-L, in all 96 complexes, which, for the original SMLC is 0.3564 A, is lowered to 0.1993 A when the model was parametrized with the inclusion of two Gaussian functions. Our results also indicate that this model is more applicable to europium complexes with beta-diketone ligands. As such, we conclude that this improved model can be considered a powerful tool for the study of lanthanide complexes and their applications, such as the modeling of light conversion molecular devices.

show abstract

“…The whole designing process would involve at least the following steps: (i) determination of the molecular structure of the proposed coordination compound, (ii) calculation of the excited states of the ligands in the coordination compound, (iii) determination of the energy transfer, radiative, and nonradiative transition rates, and (iv) solution of the rate equations to yield the temporal dependence of the populations and the luminescence quantum yield. All these steps have been at least partially solved by different theoretical approaches 13, 14, namely, the SMLC/AM1 15–17 for step (i) the INDO/S‐CI+point charge 18–21 for step (ii), the direct and exchange interactions 22, 23 for step (iii), and the 4th‐order Runge–Kutta numerical method 24, 25 for step (iv). The combination of these methodologies has yielded a practical computational tool to model and design these compounds.…”

Section: Introductionmentioning

confidence: 99%

Improved point‐charge model within the INDO/S‐CI method for describing the ligand excited states of lanthanide coordination compounds

Batista

Longo

2001

Int J of Quantum Chemistry

Self Cite

View full text Add to dashboard Cite

Due to the spatial extent of the 5s and 5p filled orbitals of lanthanide ions, the shielding of the nuclear charge is not perfect at close distances to the ion. Thus, ligand atoms should experience different effective charge depending upon their distance to the central ion. Using electrostatic arguments and ab initio calculations for Eu 3+ , we have proposed an improved model that describes the ion as an effective charge, q(r), whose value has the following radial dependence, q(r) = 3 + 14e −Ar 2 . This functional form of the point charge has been implemented into the ZINDO program and INDO/S-CI calculations have been performed for the Eu(btfa) 3 bipy, Eu(btfa) 3 · 2H 2 O, Eu(bzac) 3 bipy, and Eu(bzac) 3 · 2H 2 O compounds. The comparison with the experimental absorption spectrum was used to optimize the exponent A parameter. Application of this model to several other Eu 3+ coordination compounds yielded better results for the calculated absorption spectra than the fixed 3+ point-charge model.

show abstract

Uma metodologia para o projeto teórico de conversores moleculares de luz

Cited by 10 publications

References 23 publications

Synthesis, sparkle model and spectroscopic studies of the Eu(hfc)3·bipyO2 complex

Synthesis, sparkle model and spectroscopic studies of the Eu(hfc)3·bipyO2 complex

Sparkle Model for AM1 Calculation of Lanthanide Complexes: Improved Parameters for Europium

Improved point‐charge model within the INDO/S‐CI method for describing the ligand excited states of lanthanide coordination compounds

Contact Info

Product

Resources

About