Magnetic Anisotropy and Dipolar Shifts in Shift Reagent Systems

X-ray Diffraction and 1H NMR in Solution: Structural Determination of Lanthanide Complexes of a Py2N6Ac4 Ligand

“…These values define very large χ tensor anisotropies both along the z ‘ axis, (χ z ‘ z ‘ − 1 / 3 Tr χ ), and in the x ‘ y ‘ plane, (χ x ‘ x ‘ − χ y ‘ y ‘ ): (−398.6, 467.0) (Ce), (−695.9, 815.3) (Pr), (−270.0, 330.3) (Nd), (253.1, −296.5) (Eu), (−5441.1, 6374.2) (Tb), and (−6326.8, 7411.8) (Dy), in units of VVk/mol. Similarly to previous results, , the trends of the relative values of the χ tensor components and anisotropies along the lanthanide series follow the relative Bleaney factors C j of the various lanthanides, indicating that the crystal field parameters 〈 r 2 〉 A 2 0 and 〈 r 2 〉 A 2 2 are constant for these complexes.…”

Accessibility of Cation Site in Zeolites by 6Li MAS NMR Spectroscopy Using Paramagnetic O2 as a Chemical Shift Agent. The Example of Zeolite Li-LSX

“…NMR signals of nuclei in the vicinity of paramagnetic species are subjected to large paramagnetic shifts, line broadenings, and short relaxation times T 1 . , The effect arises primarily from hyperfine interactions 9,10 of the unpaired electron spin with the nuclear spin and depends on the configurations of the system paramagnetic species-observed atoms. Paramagnetic shifts are used for instance in lanthanide complexes or transition-metal complexes, to obtain structural information on the conformation of ligands. In the presence of paramagnetic species the T 1 of the 6 Li isotope are strongly reduced. , We take advantage of this effect to obtain spectra of higher signal-to-noise ratio.…”