Theoretical Determination of Energy Transfer Processes and Influence of Symmetry in Lanthanide(III) Complexes

Methodological Considerations

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Abstract

This work presents a theoretical protocol to analyze the symmetry effect on the allowed character of the transitions and to estimate the probability of energy transfer in lanthanide(III) complexes. For this purpose, a complete study was performed based on the multireference CASSCF/PT2 technique along with TDDFT, to build the energy level diagrams and determine the spectral overlap integrals, respectively. This approach was applied on a series of LnIII complexes, viz. [LnCl3(DMF)2(Dpq)]/[Ln(NO3)3(DMF)2(Dpq)], where Ln = SmIII, TbIII, ErIII/EuIII, NdIII and dpq = dipyridoquinoxaline, synthesized and characterized by Patra et al. (Dalton Trans. 2015, 44 (46), 19844-19855; CrystEngComm 2016, 18 (23), 4313-4322; Inorg. Chim. Acta 2016, 451, 73-81). A fragmentation scheme was applied where both the ligand and the lanthanide fragments were treated separately but at the same level of theory. The symmetry analysis only partially reproduced the expected results, and a more detailed analysis of the crystal field became necessary. On the other hand, the most probable energy transfer pathways that take place in the complexes were elucidated from the energy gaps between the ligand-localized triplet state and the emitting levels of the lanthanide fragments. These gaps, which are related to the energy transfer rate, properly reproduced the trend reported experimentally for the best and worst yields. Finally, the spectral overlap integral was calculated from the emission spectra of the dpq ligand and the absorption spectra of the lanthanide fragment. The obtained values are in good agreement with the quantum yields calculated for the systems. The most remarkable aspect of this protocol was its ability to explain the emission and nonemission of the studied compounds.

Original languageEnglish
Pages (from-to)5120-5132
Number of pages13
JournalInorganic Chemistry
Volume57
Issue number9
DOIs
Publication statusPublished - 7 May 2018

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Lanthanoid Series Elements
Energy transfer
energy transfer
fragments
ligands
symmetry
Ligands
atomic energy levels
crystal field theory
fragmentation
emission spectra
Quantum yield
energy levels
diagrams
Electron energy levels
absorption spectra
trends
Absorption spectra
Energy gap
estimates

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry

Cite this

@article{c114a5014c2c4facb0da39fbed146814,
title = "Theoretical Determination of Energy Transfer Processes and Influence of Symmetry in Lanthanide(III) Complexes: Methodological Considerations",
abstract = "This work presents a theoretical protocol to analyze the symmetry effect on the allowed character of the transitions and to estimate the probability of energy transfer in lanthanide(III) complexes. For this purpose, a complete study was performed based on the multireference CASSCF/PT2 technique along with TDDFT, to build the energy level diagrams and determine the spectral overlap integrals, respectively. This approach was applied on a series of LnIII complexes, viz. [LnCl3(DMF)2(Dpq)]/[Ln(NO3)3(DMF)2(Dpq)], where Ln = SmIII, TbIII, ErIII/EuIII, NdIII and dpq = dipyridoquinoxaline, synthesized and characterized by Patra et al. (Dalton Trans. 2015, 44 (46), 19844-19855; CrystEngComm 2016, 18 (23), 4313-4322; Inorg. Chim. Acta 2016, 451, 73-81). A fragmentation scheme was applied where both the ligand and the lanthanide fragments were treated separately but at the same level of theory. The symmetry analysis only partially reproduced the expected results, and a more detailed analysis of the crystal field became necessary. On the other hand, the most probable energy transfer pathways that take place in the complexes were elucidated from the energy gaps between the ligand-localized triplet state and the emitting levels of the lanthanide fragments. These gaps, which are related to the energy transfer rate, properly reproduced the trend reported experimentally for the best and worst yields. Finally, the spectral overlap integral was calculated from the emission spectra of the dpq ligand and the absorption spectra of the lanthanide fragment. The obtained values are in good agreement with the quantum yields calculated for the systems. The most remarkable aspect of this protocol was its ability to explain the emission and nonemission of the studied compounds.",
author = "Beltr{\'a}n-Leiva, {Mar{\'i}a J.} and Day{\'a}n P{\'a}ez-Hern{\'a}ndez and Ramiro Arratia-P{\'e}rez",
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T1 - Theoretical Determination of Energy Transfer Processes and Influence of Symmetry in Lanthanide(III) Complexes

T2 - Methodological Considerations

AU - Beltrán-Leiva, María J.

AU - Páez-Hernández, Dayán

AU - Arratia-Pérez, Ramiro

PY - 2018/5/7

Y1 - 2018/5/7

N2 - This work presents a theoretical protocol to analyze the symmetry effect on the allowed character of the transitions and to estimate the probability of energy transfer in lanthanide(III) complexes. For this purpose, a complete study was performed based on the multireference CASSCF/PT2 technique along with TDDFT, to build the energy level diagrams and determine the spectral overlap integrals, respectively. This approach was applied on a series of LnIII complexes, viz. [LnCl3(DMF)2(Dpq)]/[Ln(NO3)3(DMF)2(Dpq)], where Ln = SmIII, TbIII, ErIII/EuIII, NdIII and dpq = dipyridoquinoxaline, synthesized and characterized by Patra et al. (Dalton Trans. 2015, 44 (46), 19844-19855; CrystEngComm 2016, 18 (23), 4313-4322; Inorg. Chim. Acta 2016, 451, 73-81). A fragmentation scheme was applied where both the ligand and the lanthanide fragments were treated separately but at the same level of theory. The symmetry analysis only partially reproduced the expected results, and a more detailed analysis of the crystal field became necessary. On the other hand, the most probable energy transfer pathways that take place in the complexes were elucidated from the energy gaps between the ligand-localized triplet state and the emitting levels of the lanthanide fragments. These gaps, which are related to the energy transfer rate, properly reproduced the trend reported experimentally for the best and worst yields. Finally, the spectral overlap integral was calculated from the emission spectra of the dpq ligand and the absorption spectra of the lanthanide fragment. The obtained values are in good agreement with the quantum yields calculated for the systems. The most remarkable aspect of this protocol was its ability to explain the emission and nonemission of the studied compounds.

AB - This work presents a theoretical protocol to analyze the symmetry effect on the allowed character of the transitions and to estimate the probability of energy transfer in lanthanide(III) complexes. For this purpose, a complete study was performed based on the multireference CASSCF/PT2 technique along with TDDFT, to build the energy level diagrams and determine the spectral overlap integrals, respectively. This approach was applied on a series of LnIII complexes, viz. [LnCl3(DMF)2(Dpq)]/[Ln(NO3)3(DMF)2(Dpq)], where Ln = SmIII, TbIII, ErIII/EuIII, NdIII and dpq = dipyridoquinoxaline, synthesized and characterized by Patra et al. (Dalton Trans. 2015, 44 (46), 19844-19855; CrystEngComm 2016, 18 (23), 4313-4322; Inorg. Chim. Acta 2016, 451, 73-81). A fragmentation scheme was applied where both the ligand and the lanthanide fragments were treated separately but at the same level of theory. The symmetry analysis only partially reproduced the expected results, and a more detailed analysis of the crystal field became necessary. On the other hand, the most probable energy transfer pathways that take place in the complexes were elucidated from the energy gaps between the ligand-localized triplet state and the emitting levels of the lanthanide fragments. These gaps, which are related to the energy transfer rate, properly reproduced the trend reported experimentally for the best and worst yields. Finally, the spectral overlap integral was calculated from the emission spectra of the dpq ligand and the absorption spectra of the lanthanide fragment. The obtained values are in good agreement with the quantum yields calculated for the systems. The most remarkable aspect of this protocol was its ability to explain the emission and nonemission of the studied compounds.

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DO - 10.1021/acs.inorgchem.8b00159

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VL - 57

SP - 5120

EP - 5132

JO - Inorganic Chemistry

JF - Inorganic Chemistry

SN - 0020-1669

IS - 9

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