Role of Ligand Straining in Complexation of Eu3+–Am3+ Ions by TPEN and PPDEN, Scalar Relativistic DFT Exploration in Conjunction with COSMO-RS

Ali, Sk. Musharaf

doi:10.1021/acsomega.8b00933

“…10a, and a depiction of selected valence MOs are shown in Figure 10b. We focused on analysis of the valence orbitals rather than the electronic excitations, because, as shown in previous studies, 87,88 such analysis is sufficient to qualitatively elucidate coordination properties.…”

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

0

View full text Add to dashboard Cite

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.

show abstract

“…The MO diagrams for valence orbitals of [Eu 3+ -NA×(H2O)3] 3+ and [Eu 3+ -NA×(H2O)4] 3+ appear in Figure 10a, and a depiction of selected valence MOs are shown in Figure 10b. We focused on analysis of the valence orbitals rather than the electronic excitations, because, as shown in previous studies, 87,88 such analysis is sufficient to qualitatively elucidate coordination properties.…”

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

1

0

View full text Add to dashboard Cite

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.

show abstract

“…38 The bulk of the computational work does not report the Gibbs free energy, nor SFs, but instead focuses on comparisons of minimized structures to experimentally determined geometries, 14−20,24,26,27,40−42,45−47 or analysis of molecular orbital composition and electron density. 17,19,20,23,26−28,44−46 Relatively few papers report ΔG 298 K values, 13,25,29,30,32,43,44 and those that do, typically report stability constants for complexes on only a single metal for comparison with experiment. 25,30,43,44 For example, Wang et al calculated a SF of 5000 compared to their experimentally determined value of 60, which corresponds to an error in ΔG(298) of less than 3 kcal/mol, at the B3LYP/ECP(28/ 60)MWB-SEG/6-31G(d) level.…”

Section: ■ Introductionmentioning

confidence: 99%

“…17,19,20,23,26−28,44−46 Relatively few papers report ΔG 298 K values, 13,25,29,30,32,43,44 and those that do, typically report stability constants for complexes on only a single metal for comparison with experiment. 25,30,43,44 For example, Wang et al calculated a SF of 5000 compared to their experimentally determined value of 60, which corresponds to an error in ΔG(298) of less than 3 kcal/mol, at the B3LYP/ECP(28/ 60)MWB-SEG/6-31G(d) level. 32 Trumm et al reported SF calculations on BTP and several close analogues ranging from 7 to 80 for the separation of Cm 3+ /Eu 3+ at the B3LYP/ ECP(28/60)MWB-SEG/aug-cc-pVTZ level.…”

Section: ■ Introductionmentioning

confidence: 99%

“…There are a large number of computational and experimental studies on bis-1,2,4-triazinylpyridines (BTP, Figure a), , BTP-like compounds such as bis(1,2,4-triazinyl)bipyridines (BTBP, Figure b), as well as bis(1,2,4-triazinyl)-1,10-phenanthrolines, and their derivatives. − Computational studies of related ligands containing C, H, O, and N have also been reported, − although experimental data are largely lacking for these systems. Experimental studies of BTP-related compounds report a wide range of separation factors (SFs) with variations in closely related systems over a factor of 10 4 , − whereas in other systems the variations can range from 15 to 60 or from 4 to 50 .…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Prediction of An(III)/Ln(III) Separation by 1,2,4-Triazinylpyridine Derivatives

Mason

¹

,

Smith

²

,

Vasiliu

³

et al. 2021

View full text Add to dashboard Cite

The effect of frustrated Lewis donors on metal selectivity between actinides and lanthanides was studied using a series of novel organic ligands. Structures and thermodynamic energies were predicted in the gas phase, in water, and in butanol using 9-coordinate, explicitly solvated (H2O) Eu, Gd, Am, and Cm in the +III oxidation state as reactants in the formation of complexes with 2-(6-[1,2,4]-triazin-3-yl-pyridin-2-yl)-1H-indole (Core 1), 3-[6-(2H-pyrazol-3-yl)pyridin-2-yl]-1,2,4-triazine (Core 2), and several derivatives. These complexations were studied using density functional theory (DFT) incorporating scalar relativistic effects on the actinides and lanthanides using a small core pseudopotential and corresponding basis set. A self-consistent reaction field approach was used to model the effect of water and butanol as solvents. Coordination preferences and metal selectivity are predicted for each ligand. Several ligands are predicted to have a high degree of selectivity, particularly when a low ionization potential in the ligand permits charge transfer to Eu(III), reducing it to Eu(II) and creating a half-filled f7 shell. Reasonable separation is predicted between Cm(III) and Gd(III) with Core 1 ligands, possibly due to ligand donor frustration. This separation is largely absent from Core 2 ligands, which are predicted to lose their frustration due to proton transfer from the 2N to the 3N position of the pyrazole component of the ligands via tautomerization.

show abstract

Role of Ligand Straining in Complexation of Eu³⁺–Am³⁺ Ions by TPEN and PPDEN, Scalar Relativistic DFT Exploration in Conjunction with COSMO-RS

Cited by 8 publications

References 83 publications

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

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

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

Prediction of An(III)/Ln(III) Separation by 1,2,4-Triazinylpyridine Derivatives

Contact Info

Product

Resources

About