scholarly journals Challenging lanthanide relaxation theory: erbium and thulium complexes that show NMR relaxation rates faster than dysprosium and terbium analogues

2015 ◽  
Vol 17 (25) ◽  
pp. 16507-16511 ◽  
Author(s):  
Alexander M. Funk ◽  
Peter Harvey ◽  
Katie-Louise N. A. Finney ◽  
Mark A. Fox ◽  
Alan M. Kenwright ◽  
...  
Keyword(s):  
Lanthanide Complexes ◽  
Nmr Relaxation ◽  
Paramagnetic Relaxation ◽  
Relaxation Behaviour ◽  
Relaxation Rates ◽  
Relaxation Theory

The unususal relaxation behaviour of lanthanide complexes in solution exposes the limitations of paramagnetic relaxation theory.

Another challenge to paramagnetic relaxation theory: a study of paramagnetic proton NMR relaxation in closely related series of pyridine-derivatised dysprosium complexes

2016 ◽  
Vol 18 (6) ◽  
pp. 4370-4375 ◽  
Author(s):  
Nicola J. Rogers ◽  
Katie-Louise N. A. Finney ◽  
P. Kanthi Senanayake ◽  
David Parker
Keyword(s):  
Proton Nmr ◽  
Nmr Relaxation ◽  
Paramagnetic Relaxation ◽  
Relaxation Behaviour ◽  
Relaxation Theory ◽  
Related Series

The surprising sensitivity of the relaxation behaviour of twelve dysprosium complexes in solution highlights limitations in paramagnetic relaxation theory.

Structure and Dynamics of Spherical and Rodlike Alkyl Ethoxylate Surfactant Micelles Investigated Using NMR Relaxation and Atomistic Molecular Dynamics Simulations

2019 ◽  
Author(s):  
Allison Edwards ◽  
Abdolreza Javidialesaadi ◽  
Katie Weigandt ◽  
George Stan ◽  
Charles Eads
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Nmr Relaxation ◽  
Cross Relaxation ◽  
Relaxation Rates ◽  
Surfactant Micelles ◽  
Cylindrical Micelles ◽  
Spherical Micelles ◽  
Dynamics Simulations ◽  
Relative Motions

We study molecular arrangements and dynamics in alkyl ethoxylate nonionic surfactant micelles by combining high field (600 and 700 MHz) NMR relaxation measurements with large-scale atomistic molecular dynamics simulations. For spherical micelles, but not for cylindrical micelles, cross relaxation rates are positive only for surfactant alkyl tail atoms connected to the hydrophilic head group. All cross relaxation rates are negative for cylindrical micelles. This effect is reproducible either by changing composition (ratios of the nonionic surfactants) or changing temperature of a single surfactant in order to change the micelle shape. We validate the micelle shape by SANS and use the results as a guide for our simulations. We calculate parameters that determine relaxation rates directly from simulated trajectories, without introducing specific functional forms. Results indicate that relative motions of nearby atoms are liquid-like, in agreement with 13C T1 measurements, though constrained by micelle morphology. Relative motions of distant atoms have slower components because the relative changes in distances and angles are smaller when the moving atoms are further apart. The slow, long-range motions appear to be responsible for the predominantly negative cross relaxation rates observed in NOESY spectra. The densities of atoms from positions 1 and 2 in the boundary region are lower in spherical micelles compared to cylindrical micelles. Correspondingly, motions in this region are less constrained by micelle morphology in the spherical compared to the cylindrical cases. The two effects of morphology lead to the unusual occurrence of positive cross relaxation involving positions 1 and 2 for spheres.

A family of one-dimensional lanthanide complexes bridged by two distinct carboxylate ligands with the Dy analogue displaying magnetic relaxation behaviour

2017 ◽  
Vol 46 (41) ◽  
pp. 14114-14121 ◽  
Author(s):  
Wen-Hua Zhu ◽  
Xia Xiong ◽  
Chen Gao ◽  
Shan Li ◽  
Yan Zhang ◽  
...  
Keyword(s):  
Magnetic Relaxation ◽  
Lanthanide Complexes ◽  
Relaxation Behaviour ◽  
Carboxylate Ligands ◽  
One Dimensional ◽  
Synthetic Strategy

Utilizing two different carboxylate ligands to construct dysprosium SMMs with relatively good performance was proven to be a successful synthetic strategy.

13C NMR Relaxation Rates in the Ionic Liquid 1-Ethyl-3-methylimidazolium Butanesulfonate

2006 ◽  
Vol 110 (3) ◽  
pp. 868-874 ◽  
Author(s):  
Norman E. Heimer ◽  
John S. Wilkes ◽  
Phillip G. Wahlbeck ◽  
W. Robert Carper
Keyword(s):  
Ionic Liquid ◽  
13C Nmr ◽  
Nmr Relaxation ◽  
Relaxation Rates

Molecular Reorientation of Methanol in Mixtures with Carbon Tetrachloride

1992 ◽  
Vol 47 (7-8) ◽  
pp. 857-864 ◽  
Author(s):  
M. D. Zeidler ◽  
D. S. Gill ◽  
M. D. Zeidler
Keyword(s):  
Carbon Tetrachloride ◽  
Composition Dependence ◽  
Nmr Relaxation ◽  
Dipolar Interaction ◽  
Coupling Constants ◽  
Proton Relaxation ◽  
Relaxation Rates ◽  
Molecular Reorientation ◽  
Quadrupole Coupling ◽  
Interaction Contribution

Abstract Proton and oxygen-17 nmr relaxation rates of CD317OH as well as deuteron nmr relaxation rates of CH3OD were measured in mixtures with carbon tetrachloride at different compositions and temperatures. By varying the 170-content different contributions to the proton relaxation rate could be separated and from the 17O-H dipolar interaction contribution the correlation time τ2OH of the OH bond was determined. Using these correlation times the composition dependence of the deuterium and oxygen-17 quadrupole coupling constants of methanol was derived. A strong variation of the coupling constants over the measured composition range is evident

scholarly journals Methyl Group Rotation and Tunnellingin Crystals of 5-Membered Ring Molecules

1988 ◽  
Vol 43 (1) ◽  
pp. 35-42 ◽  
Author(s):  
A.-S. Montjoie ◽  
W. Müller-Warmuth ◽  
Hildegard Stiller ◽  
J. Stanislawski
Keyword(s):  
Elevated Temperatures ◽  
Inelastic Neutron Scattering ◽  
Relaxation Times ◽  
Nmr Relaxation ◽  
Lattice Relaxation ◽  
Inelastic Neutron ◽  
Spin Lattice Relaxation ◽  
Relaxation Rates ◽  
Quantum Tunnelling ◽  
Spin Lattice

Abstract1H NMR spin-lattice relaxation times T1 and -if accessible -level-crossing peaks and inelastic neutron scattering spectra have been measured for solid 2-and 3-methylfuran, 2-and 3-methylthiophene, 3-and 4-methylpyrazole, 1-methylimidazole, and 5-methylisoxazole. From the tunnel splittings, the torsional excitations and the NMR relaxation rates, the molecular dynamics of the methyl rotators has been evaluated between the limits of quantum tunnelling at low temperatures and thermally activated random reorientation at elevated temperatures.

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