25-30 August 2019
Henry Ford Building
Europe/Berlin timezone

Lanthanide-induced relaxation anisotropy

27 Aug 2019, 12:30
30m
Lecture Hall A (Henry Ford Building)

Lecture Hall A

Henry Ford Building

Talk Dynamics Dynamics

Speaker

Dr Elizaveta Suturina (University of Bath)

Description

Lanthanide ions accelerate nuclear spin relaxation by two primary mechanisms: dipolar and Curie. Both are commonly assumed to depend on the length of the lanthanide-nucleus vector, but not on its direction. In this communication, we demonstrate experimentally and verify theoretically that this is wrong – careful proton relaxation data analysis in a series of isostructural lanthanide complexes (Ln=Tb, Dy, Ho, Er, Tm, Yb) reveals angular dependence in both Curie and dipolar relaxation. The reasons are:

  1. that magnetic susceptibility anisotropy can be of the same order
    of magnitude as the isotropic part (contradicting the unstated
    assumption in Gueron‘s theory of the Curie relaxation process [1]);

  2. that zero-field splitting can be much stronger than the electron
    Zeeman interaction (Bloembergen’s original theory of the
    lanthanide-induced dipolar relaxation process makes the opposite
    assumption [2]).

These factors go beyond cross-correlation effects; they alter the relaxation theory treatment and make angular dependencies appear in the nuclear spin relaxation rates. Those angular dependencies are impossible to ignore – we demonstrate this both theoretically and experimentally, and suggest that a major revision is needed of the way lanthanide-induced relaxation data is used in structural biology.

Primary authors

Dr Elizaveta Suturina (University of Bath) Dr Kevin Mason (University of Durham) Prof. Carlos Geraldes (University of Coimbra) Dr Nicholas Chilton (University of Manchester) Prof. David Parker (University of Durham) Prof. Ilya Kuprov (University of Southampton)

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