Luminescent europium(<scp>iii</scp>) and terbium(<scp>iii</scp>) complexes of β-diketonate and substituted terpyridine ligands: synthesis, crystal structures and elucidation of energy transfer pathways

Abbas, Zaffar; Dasari, Srikanth; Beltrán-Leiva, María J.; Cantero-López, Plinio; Páez‐Hernández, Dayán; Arratia‐Pérez, Ramiro; Butcher, Ray J.; Patra, Ashis K.

doi:10.1039/c9nj02838b

Cited by 41 publications

(30 citation statements)

References 128 publications

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“…Calculated absorption spectra using B3LYP /6–311++G(d,p) of fragments from crystallographic cif files. The experimental spectra of the Eu 3+ complexes, as in Figure , are in red on arbitrary scales.…”

Section: Comparison Of the Absorption Spectra With Those Calculated U...mentioning

confidence: 99%

“…Calculations employing relativistically recontracted Karlsruhe (Douglas–Kroll–Hess – DKH or zero-order regular approximation for relativistic effects – ZORA) basis sets , with segmented all-electron relativistically contracted basis sets or atomic natural orbital basis sets are often impracticable for sets of lanthanide complexes because of the immense time required. Hence, many time dependent–density functional theory (TD-DFT) calculations − have been attempted on lanthanide ion complexes using effective core potentials (ECPs), which place the electronic ground state as a 4f N configuration (for example, a high spin septet for Eu 3+ using the Stuttgart group ECP 28MWB , or as a closed shell: 52MWB for Eu 3+ ) . In the latter case, the intra-4f N energy levels of Eu 3+ are not considered and only the relevant ligand levels in the complex are calculated.…”

Section: Introductionmentioning

confidence: 99%

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Determination of Triplet State Energy and the Absorption Spectrum for a Lanthanide Complex

et al. 2021

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The usual depiction of energy transfer from an antenna of a lanthanide complex, LnL n , to the lanthanide ion, Ln3+, such as Eu3+ or Tb3+, is illustrated by an energy diagram matching the complex and metal ion levels. Other than direct singlet energy transfer (ET), relaxation to the lowest triplet state, T1, may be followed by ET. The determination of the zero phonon line triplet state energy, T1, is thus essential for the rationalization of the ET processes of lanthanide ions. It is also useful to calculate the electronic absorption spectra of lanthanide complexes to pinpoint maximum absorption. The triplet state energy and the energies of absorption bands have not been thoroughly investigated by calculation and compared with experimental results in a critical manner previously. In order to study and provide guidelines on these points, we have made an experimental and theoretical investigation of the energy levels of lanthanide complexes in the solid state and in solution by employing well-characterized compounds. It is found that time dependent–density functional theory (TD-DFT) methods do not provide a good indication of the complex absorption spectrum, but reasonable agreement is achieved from multireference methods or more rapidly from the Zerner’s intermediate neglect of differential overlap (ZINDO/S) semiempirical method for calculating excited states. Although the absorption spectra of the complexes may be similar for different lanthanide ions and may be fairly similar to those of the ligands, the use of a fragment scheme to calculate absorption spectra using TD-DFT is generally not accurate. The major absorption bands correspond to higher energy singlet transitions and the energies of the first singlet and triplet states are not well-predicted by the above methods. The calculation of the triplet zero phonon line energy is best performed by the correction of the adiabatic transition energy by the difference in the zero-point vibrational energy of the ground singlet (S0) and the triplet (T1) states: the ΔSCF (self-consistent field) method. The geometry optimization of the complex in each electronic state followed by confirmatory vibrational frequency calculations is thus required. This study lays down the platform for a more accurate description and understanding of the ET processes of lanthanide ions in organic complexes.

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Section: Comparison Of the Absorption Spectra With Those Calculated U...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Determination of Triplet State Energy and the Absorption Spectrum for a Lanthanide Complex

et al. 2021

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“…19 As a whole, in most cases in the literature it can be seen that the energy of the 5 D 0 emitter is not correctly reproduced. 17,19,20,22,23,28 Recently, hybrid approaches combining the computationally efficient qualities of semiempirical methods and the accuracy of full ab initio calculationsthe CERES 29 program is one prime examplehave started to catch on. In these suites of programs, a specific ab initio protocol is optimized and set up for the determination of certain observables.…”

Section: Introductionmentioning

confidence: 99%

Multireference Ab Initio Investigation on Ground and Low-Lying Excited States: Systematic Evaluation of J–J Mixing in a Eu³⁺ Luminescent Complex

Babetto

Carlotto

et al. 2020

Inorg. Chem.

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A theoretical protocol combining density functional theory (DFT) and multireference (CAS) calculations is proposed for a Eu3+ complex. In the complex, electronic levels of the central Eu3+ ion are correctly calculated at the CASPT2 level of theory, and the effect of introducing different numbers of states in the configuration interaction matrices is highlighted as well as the shortcomings of DFT methods in the treatment of systems with high spin multiplicity and strong spin–orbit coupling effects. For the 5D0 state energy calculation, the inclusion of states with different multiplicity and the number of states considered for each multiplicity are crucial parameters, even if their relative weight is different. Indeed, the addition of triplet and singlets is important, while the number of states is relevant only for the quintets. The herein proposed protocol enables a rigorous, full ab initio treatment of Eu3+ complex, which can be easily extended to other Ln3+ ions.

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“…TDDFT or multi-reference calculations are necessary for more robust quantitative validation of Ln 3+ complexes stabilities; 32,[89][90][91][92] however, in this work we focus on describing the structure of the complexes, and we will quantify stabilities in the near future. Thus, in the present paper, we provide a qualitative description of the electronic structure of the previously unresolved Eu 3+nicotianamine complexes to complement our molecular structure findings (Section III.B).…”

Section: Iiid Electronic Structure Of Eu 3+ -Ligand Complexesmentioning

confidence: 99%

Solution Structure of a Europium-Nicotianamine Complex Supports That Phytosiderophores Bind Lanthanides

Kaliakin¹,

Monteiro²,

Bettencourt‐Dias³

et al. 2020

Preprint

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We report the solution structure of a europium-nicotianamine complex predicted from ab initio molecular dynamics simulations with density functional theory. Emission and excitation spectroscopy measurements show that the Eu3+coordination environment changes in the presence of nicotianamine, suggesting complex formation, and strongly supporting the predicted Eu3+-nicotianamine complex structure from computation. We used our recently optimized pseudopotentials and basis sets for lanthanides to model Eu3+-ligand complexes with explicit water molecules in periodic boxes, effectively simulating the solution phase. Our simulations consider possible chemical events (e.g. coordination bond formation, protonation state changes, charge transfers), as well as ligand flexibility and solvent rearrangements. Our computational approach correctly predicts the solution structure of a Eu3+-ethylenediaminetetraacetic acid complex within 0.05 Å of experimentally measured values, backing the fidelity of the predicted solution structure of the Eu3+-nicotianamine complex. Emission and excitation spectroscopy measurements were also performed on the well-known Eu3+-ethylenediaminetetraacetic acid complex to validate our experimental methods. The electronic structure of the Eu3+-nicotianamine complex is analyzed to describe electron densities and coordination bonds in greater detail. Nicotianamine is a metabolic precursor of, and structurally very similar to, phytosiderophores, which are responsible for the uptake of metals in plants. Although knowledge that nicotianamine binds europium does not determine how plants uptake rare earths from the environment, it strongly supports that phytosiderophores bind lanthanides.

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Luminescent europium(iii) and terbium(iii) complexes of β-diketonate and substituted terpyridine ligands: synthesis, crystal structures and elucidation of energy transfer pathways

Abstract: A series of coordinatively saturated LnIII complexes: [Ln(R-TPY)(TTA)3] (1–6) were designed and structurally characterized and plausible energy transfer (ET) pathways determined using a theoretical method.

Cited by 41 publications

References 128 publications

Determination of Triplet State Energy and the Absorption Spectrum for a Lanthanide Complex

Determination of Triplet State Energy and the Absorption Spectrum for a Lanthanide Complex

Multireference Ab Initio Investigation on Ground and Low-Lying Excited States: Systematic Evaluation of J–J Mixing in a Eu³⁺ Luminescent Complex

Solution Structure of a Europium-Nicotianamine Complex Supports That Phytosiderophores Bind Lanthanides

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Luminescent europium(iii) and terbium(iii) complexes of β-diketonate and substituted terpyridine ligands: synthesis, crystal structures and elucidation of energy transfer pathways

Abstract: A series of coordinatively saturated LnIII complexes: [Ln(R-TPY)(TTA)3] (1–6) were designed and structurally characterized and plausible energy transfer (ET) pathways determined using a theoretical method.

Cited by 41 publications

References 128 publications

Determination of Triplet State Energy and the Absorption Spectrum for a Lanthanide Complex

Determination of Triplet State Energy and the Absorption Spectrum for a Lanthanide Complex

Multireference Ab Initio Investigation on Ground and Low-Lying Excited States: Systematic Evaluation of J–J Mixing in a Eu3+ Luminescent Complex

Solution Structure of a Europium-Nicotianamine Complex Supports That Phytosiderophores Bind Lanthanides

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Multireference Ab Initio Investigation on Ground and Low-Lying Excited States: Systematic Evaluation of J–J Mixing in a Eu³⁺ Luminescent Complex