Pseudocontact shifts in lanthanide complexes with variable crystal field parameters

Pietro, Sebastiano Di; Piano, Samuele Lo; Bari, Lorenzo Di

doi:10.1016/j.ccr.2011.05.010

Cited by 46 publications

(57 citation statements)

References 43 publications

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“…For details we refer to the specific literature. 62,63 For this mechanism, in the common case of a distorted square antiprismatic geometry, as found for example in DOTA-like complexes or in tetrakis diketonates (notably in the case of CsEuL 6 4 ), the CPL signal should vary with the twist angle ϕ following a sin(4ϕ) trend, so the maximum is reached for ϕ = 22.5° (Fig. 8).…”

Section: Static Couplingmentioning

confidence: 90%

“…62,63 For this mechanism, in the common case of a distorted square antiprismatic geometry, as found for example in DOTA-like complexes or in tetrakis diketonates (notably in the case of CsEuL 6 4 ), the CPL signal should vary with the twist angle ϕ following a sin(4ϕ) trend, so the maximum is reached for ϕ = 22.5° (Fig. Lanthanide complexes often show isostructurality along the series; this means that the geometry of the system may show no significant dependence on the lanthanide ion.…”

Section: Static Couplingmentioning

confidence: 99%

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Lanthanide Circularly Polarized Luminescence: Bases and Applications

2014

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Lanthanide (III) luminescence is very characteristic: it is characterized by narrow emission bands, large Stokes shift, and a long excited state lifetime. Moreover, chiral lanthanide complexes can emit strongly circularly polarized light in a way that is almost precluded to purely organic molecules. Thanks to the sensitivity and specificity of the Ln circularly polarized luminescence (CPL) signal, CPL-active complexes are therefore employed as bioanalytical tools and other uses can be envisaged in many other fields. Here we present a brief overview of the most recently developed CPL-active lanthanide complexes and a selected few examples of their applications. We briefly discuss the main mechanisms that can rationalize the observed outstanding CPL properties of these systems, and some practical suggestions on how to measure and report data.

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Section: Static Couplingmentioning

confidence: 90%

Section: Static Couplingmentioning

confidence: 99%

Lanthanide Circularly Polarized Luminescence: Bases and Applications

2014

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“…Hereafter, they will be referred to as fast relaxing Ln 3+ ions. However, their fast electronic relaxation is very useful since it allows one to determine the geometry of their LnL complexes (L = ligand) from the induced paramagnetic dipolar shifts of the resonance frequencies of the ligand nuclei [18][19][20] and to efficiently investigate the intermolecular interactions of these complexes with solvent and solute species. 21 For a given ligand, the geometries of the LnL complexes of the various Ln 3+ ions are generally very similar so that any LnL complex inducing appropriate shifts can serve as structural representative of the whole family.…”

Section: Introductionmentioning

confidence: 99%

Quantitative interpretation of the very fast electronic relaxation of most Ln3+ ions in dissolved complexes

Fries

Bélorizky

2012

The Journal of Chemical Physics

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In a reference frame rigidly bound to the complex, we consider two Hamiltonians possibly at the origin of the very fast electronic relaxation of the paramagnetic lanthanide Ln(3+) ions (Ln = Ce to Nd, Tb to Yb), namely the mean (static) ligand-field Hamiltonian and the transient ligand-field Hamiltonian. In the laboratory frame, the bombardment of the complex by solvent molecules causes its Brownian rotation and its vibration-distorsion dynamics governing the fluctuations of the static and transient terms, respectively. These fluctuations are at the origin of electronic relaxation. The electronic relaxation of a Ln(3+) ion is defined by the decays of the time correlation functions (TCFs) of the longitudinal and transverse components of the total angular momentum J of its ground multiplet. The Brownian rotation of the complex and its vibration-distorsion dynamics are simulated by random walks, which enable us to compute the TCFs from first principles. It is shown that the electronic relaxation is governed mainly by the magnitude of the transient ligand-field, and not by its particular expression. The range of expected values of this ligand-field together with the lower limit of relaxation time enforced by the values of the vibration-distortion correlation time in liquids give rise to effective electronic relaxation times which are in satisfactory overall agreement with the experimental data. In particular, these considerations explain why the electronic relaxation times vary little with the coordinating ligand and are practically independent of the external field magnitude.

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“…Linearity of δ i para,Yb vs. δ i para,Ln reveals isostructurality between the Yb 3+ and the Ln-compounds, 37 which is indeed the case for all systems from Tb 3+ to Tm 3+ . This condition ensures that separation of Fermi contact and pseudocontact shifts can be obtained through the method described in previous work, 37 with the results displayed in Tables 1 and 2.…”

Section: Results and Discussion Nmr Characterizationmentioning

confidence: 62%

“…With the aid of 1 H relaxation rates, of homo-and heteronuclear correlation spectra, and following a protocol based on eqs. (1-5) described elsewhere, 16,19,36,37 we obtained the complete assignment of the NMR spectrum of KYbL 2 .…”

Section: Results and Discussion Nmr Characterizationmentioning

confidence: 99%

Synthesis, Structural Characterization, and Chiroptical Studies of Bidentate Salen‐Type Lanthanide (III) Complexes

et al. 2015

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The salen-type ligand prepared with (R,R) diphenylethan-1,2-diamine and salicylaldehyde provides stable and inert complexes KLnL2 upon simple reaction with lanthanide halides or pseudohalides LnX3 (Ln = Tb(3+) -Lu(3+) ; X = Cl(-) or TfO(-) ) of its potassium salt. All the complexes were completely characterized through nuclear magnetic resonance (NMR), electronic circular dichroism (ECD) in the UV and some (Er(3+) , Tm(3+) , Yb(3+) ) also with Near-IR ECD (NIR-ECD) and luminescence (Tb(3+) , Tm(3+) ). Careful analysis of the NMR shifts demonstrated that the complexes are isostructural in solution and afforded an accurate geometry. This was further confirmed by means of Density Functional Theory (DFT) optimization of the Lu(3+) complex, and by comparing the ligand-centered experimental and time-dependent TD-DFT computed UV-ECD spectra. As final validation, we used the NIR-ECD spectrum of the Yb(3+) derivative calculated by means of Richardson's equations. The excellent match between calculated and experimental ECD spectra confirm the quality of the NMR structure.

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Pseudocontact shifts in lanthanide complexes with variable crystal field parameters

Cited by 46 publications

References 43 publications

Lanthanide Circularly Polarized Luminescence: Bases and Applications

Lanthanide Circularly Polarized Luminescence: Bases and Applications

Quantitative interpretation of the very fast electronic relaxation of most Ln3+ ions in dissolved complexes

Synthesis, Structural Characterization, and Chiroptical Studies of Bidentate Salen‐Type Lanthanide (III) Complexes

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