Lanthanide shift reagents. Survey

Horrocks, William DeW.; Sipe, James P.

doi:10.1021/ja00754a016

Cited by 152 publications

(37 citation statements)

References 8 publications

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“…24 The LIS in NMR experiments has been related to the crystal field parameters B 2 0 and B 2 2 that determine the magnetic anisotropy, D, in Bleaney's theory. 28,29 For several isostructural series of complexes, this relationship has been proven correct by comparing the values of D through the lanthanides series 30,31 or by relating NMR and optical spectra. 24,32 In addition to a correlation between B 2 0 measured in the emission spectrum of europium with LIS, the intensity of the CD band centered around 976 nm in the spectrum of YbDOTAMPh was found to correlate moderately well with the LIS in the NMR spectra, leading to speculation that the B 2 0 coefficient manifests itself in both of these parameters.…”

Section: Near-infrared Circular Dichroism (Nir-cd) Spectroscopymentioning

confidence: 99%

Structural and Chiroptical Properties of the Two Coordination Isomers of YbDOTA-Type Complexes

et al. 2005

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Studies of the structural, physical, and chemical properties of the lanthanide(III) complexes of DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) and related ligands are often complicated by the presence of two coordination isomers in solution. Since these coordination isomers are in exchange and cannot be separated, many techniques offer information only on the weighted average of the two isomers. Lanthanide ion complexes formed with the ligands S(RRRR)NO 2 BnDOTMA and S(SSSS)NO 2 BnDOTMA preferentially adopt only one of the two common coordination isomers in solution, so the ytterbium complexes of these ligands offer a unique opportunity to study the nearinfrared circular dichroism (NIR-CD) characteristics of each coordination geometry in isolation. The spectra acquired support many of the conclusions and assumptions of previous studies and demonstrate that this spectroscopy is particularly sensitive to the distortion of the coordination polyhedron. This will have particularly relevant consequences when studying achiral YbDOTA-like systems forming labile adducts with (chiral) hosts and receptors.

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Section: Near-infrared Circular Dichroism (Nir-cd) Spectroscopymentioning

confidence: 99%

Structural and Chiroptical Properties of the Two Coordination Isomers of YbDOTA-Type Complexes

et al. 2005

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“…The decrease in the bond length to oxygen by about 0.08 /~ can be attributed to the lanthanide contraction (Shannon & Prewitt, 1969) pyridine than are similar complexes of the other lanthanides (Hinckley, 1971). The molecular structure of this complex closely resembles that of Ho(dpm)~(4-pic)~ (Horrocks, Sipe & Luber, 1971), but the crystal structure is quite different. Ho(dpm)~(4-pic)z crystallizes in the orthorhombic space group Pbcn with the crystallographic C2 axis passing through the Ho(III) ion.…”

Section: Discussionmentioning

confidence: 77%

“…The potential for deducing the structural details of substrate molecules coordinated to Ln(dpm)3 complexes (Ln is lanthanide; dpm is dipivalomethanato or 2,2,6,6-tetramethylheptane-3,5-dionato) has led several authors to postulate various correlations between the induced shifts and various structural parameters (Sievers, 1972). The most successful treatments have been those which relate the observed shifts to a geometric factor G(r,O) given as (3 cos 2 0-1)/r 3 (Horrocks & Sipe, 1971). This geometric factor occurs in one form of the dipolar shift equation, which is valid only for molecules with axial (n-fold, n>3) symmetry.…”

Section: Introductionmentioning

confidence: 99%

The crystal and molecular structure of a europium shift reagent complex, the dipyridine adduct of tris-(2,2,6,6-tetramethylheptane-3,5-dionato)-europium(III), Eu(dpm)3(py)2

Cramer¹,

Seff²

1972

Acta Crystallogr Sect B

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The crystal structure of the dipyridine adduct of tris-(2,2,6,6-tetramethylheptane-3,5-dionato)europium-(III), Eu(dpm)3(py)2, has been determined so that the principal features of its paramagnetically shifted n.m.r, spectrum could be calculated. The crystals form as triclinic parallelepipeds in space group PT with a= 13.611 (5), b= 17.306 (4), c= 10.493 (7)A, e=93"33 (3), fl= 105.20 (5), and y=94-75 (4) °, with two molecules per unit cell. All unique reflections for which 20< 50 ° were observed using graphite monochromatized Mo Ke radiation and a pulse-height analyzer. The structure was refined by large-block diagonal least-squares methods, using 6840 observed reflections, to an R index of 0"039. Most hydrogen atoms were located, and the remainder have been included at their calculated positions. The Eu(dpm)3(py)2 molecule contains a near twofold axis, and the coordination sphere is best described as a square antiprism. Eu(III) lies 0-3 to 0"4 A out of the molecular planes of four ofthefive ligands. Because of the low symmetry of the complex, two geometric factors are needed to account for the observed n.m.r.shirts.

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“…Thus, a correlation of isotropic shift with distance and angle from the coordinated lanthanide ion would be anticipated according to Eq. 1 (15)(16)(17)(18)(19)(20)(21)(22). A = AH/H = C(3 cos' 0 -l)r- [1] In this equation, A is the isotropic shift for a given nucleus, 0 is the angle between the appropriate symmetry axis of the complex and the metal-nucleus vector, and r is the vector magnitude.…”

Section: Origin and Utility Of The Isotropic Nmr Shiftmentioning

confidence: 99%

“…however, their use in obtaining structural information has been a subject of some controversy (12,(15)(16)(17)(18)(19)(20)(21)(22) (13).…”

Section: Origin and Utility Of The Isotropic Nmr Shiftmentioning

confidence: 99%

Lanthanide Ion-Induced Isotropic Shifts and Broadening for Nuclear Magnetic Resonance Structural Analysis of Model Membranes

Andrews

Faller

Gilliam

et al. 1973

Proc. Natl. Acad. Sci. U.S.A.

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The effects of a series of aquated lanthanide ions on the nuclear magnetic resonance spectrum of phospholipid bilayer suspensions are reported. The ability of these ions to provide a spectral distinction between morphologically exterior resonances and their interior counterparts was confirmed. Measurements of the relative shifting and broadening capabilities of these ions are reported, and their correlation with solid-state magnetic susceptibility anisotropies is shown to implicate a dipolar (pseudocontact) mechanism as the source of this effect. The potential for the use of dipolar shifts as structural probes is discussed and an alternative method using dipolar shifting and broadening reagents simultaneously is presented.The use of nuclear magnetic resonance spectroscopy (NMR) as a tool for the study of artificial phospholipid bilayers (a model membrane system), as well as biological membranes themselves, has been of great current interest. Recently, Bystrov et al. (1) reported the 1H NMR spectrum of a phospholipid bilayer in the presence of aquated Eu+3 ions, in which they observed an upfield shift of a portion of the N-methyl choline resonance, which originally had been a strong singlet in the absence of Eu+3. A dependence of the magnitude of the shift on the concentration of europium was also noted. These workers advanced the explanation that this metal ion, by coordination to the exterior phosphate head groups, was capable of lifting the accidental chemical shift equivalence of the protons on the inside and outside of the closed bilayers. The spectral result was thus two singlets, corresponding to the (-NMe3) i and (-NMe3), groups. Presumably, the outer protons experienced an isotropic shift due to the paramagnetic ion and the inner protons remained unshifted. Other reagents that induce spectral modifications of this kind have been reported and include small chemical shifts induced through the agency of anions (2, 3) and elemental iodine (2), and broadening of resonances by the paramagnetic Mn+2 and Gd+3 ions (1, 3, 4).It is evident that a technique capable of deriving quantitative information on the molecular disposition of membrane components would be of great value, and the reagents described above are potentially useful in this context. This apAbbreviations: (-X-)i and (-X-)0, resonance assignments for those portions of an NMR (nuclear magnetic resonance) signal arising from chemically similar but spatially distinct nuclei residing on the inside and outside of a closed bilayer, respectively; Ln +3, a generic, trivalent lanthanide ion; a, isotropic chemical shift in ppm relative to the unshifted portion of the same resonance; vP/2, full observed resonance width at half-height; V1/2', full corrected width at half-height, i.e., V1/2 (observed) -vl/2 (natural).pears to be particularly true of the Eu+3 ion, by virtue of the larger changes involved. Thus, in connection with the problem of site-labeling of membrane constituents, we sought to investigate the utility of lanthanide ions as structural prob...

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Lanthanide shift reagents. Survey

Cited by 152 publications

References 8 publications

Structural and Chiroptical Properties of the Two Coordination Isomers of YbDOTA-Type Complexes

Structural and Chiroptical Properties of the Two Coordination Isomers of YbDOTA-Type Complexes

The crystal and molecular structure of a europium shift reagent complex, the dipyridine adduct of tris-(2,2,6,6-tetramethylheptane-3,5-dionato)-europium(III), Eu(dpm)3(py)2

Lanthanide Ion-Induced Isotropic Shifts and Broadening for Nuclear Magnetic Resonance Structural Analysis of Model Membranes

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