Origin of lanthanide nuclear magnetic resonance shifts and their uses

Chemical Exchange Saturation Transfer Contrast Agents for Magnetic Resonance Imaging

“…The discovery of such slow water exchange complexes suggested to us that such lanthanide-based chelates might be used as paramagnetic CEST agents (PARACEST) (48,49). The Gd 3+ ion is isotropic (seven unpaired electrons in seven 4f orbitals) so it cannot act as a shift reagent, but other paramagnetic lanthanide ions with anisotropic distributions of their f-electrons can induce very large shifts in the resonance frequencies of proximate protons (50)(51)(52). Some of those other lanthanides, when complexed with DOTA-tetraamide ligands, exhibit a single, highly shifted metal ion-bound water resonance in their 1 H NMR spectra due to slow water exchange (49).…”

Expanding the utility of NMR restraints with paramagnetic compounds: Background and practical aspects

“…Sm and Eu have low-lying excited states [138] which result in a small population difference between the ground and the first excited state. This leads to small relaxation and line-broadening effects [58].…”

Local structure and magnetism of LaxEu1−xPO4Martel1, Rakhmatullin2, Baldoví3 et al. 2019Phys. Rev. B6030View full textAdd to dashboardCite

“…As the same interaction acts for the shielding and the shift, we considered that a linear relation exists between these two parameters following the equation δ PC2 = a.σ PC1 (with a as the scaling factor). This rescaling was previously applied by Bleaney et al [86] and gave good results. The two approaches provided similar pseudocontact shift values (δ PC1 and δ PC2 , cf.…”

“…The anisotropic part of the shift by Eu 3+ has been analyzed by Bleaney separately from the other rare-earth cations due to its nonmagnetic ground state (J = 0). He considered that the PC is only due to the anisotropy in the magnetic susceptibility, that the ELs are nondegenerate (original Van Vleck theory) and the excited states (J = 1, 2, and 3) have to be considered [26,86].…”