The University of Southampton
University of Southampton Institutional Repository

Lanthanide‐induced relaxation anisotropy

Lanthanide‐induced relaxation anisotropy
Lanthanide‐induced relaxation anisotropy
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. Here we show experimentally 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: (a) that magnetic susceptibility anisotropy can be of the same order of magnitude as the isotropic part (contradicting the unstated assumption in Guéron‘s theory of the Curie relaxation process), and (b) 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). These factors go beyond the well researched cross-correlation effects; they alter the relaxation theory treatment and make strong angular dependencies appear in the nuclear spin relaxation rates. Those dependencies are impossible to ignore – this is now demonstrated both theoretically and experimentally, and suggests that a major revision is needed of the way lanthanide-induced relaxation data are used in structural biology.
1463-9076
17676-17686
Suturina, Elizaveta
24dd007d-949a-4852-99d1-ea42b00103ef
Mason, Kevin
b44d68df-9067-4812-a742-ff17df162f4b
Geraldes, Carlos F.G.C.
c109bc54-a4f6-4d80-8bc8-bf30f8d3fce1
Chilton, Nicholas F.
850941d1-c8bf-40fd-abaa-6a5467a0e549
Parker, David
31bfb567-907a-4490-af57-411089ae0e73
Kuprov, Ilya
bb07f28a-5038-4524-8146-e3fc8344c065
Suturina, Elizaveta
24dd007d-949a-4852-99d1-ea42b00103ef
Mason, Kevin
b44d68df-9067-4812-a742-ff17df162f4b
Geraldes, Carlos F.G.C.
c109bc54-a4f6-4d80-8bc8-bf30f8d3fce1
Chilton, Nicholas F.
850941d1-c8bf-40fd-abaa-6a5467a0e549
Parker, David
31bfb567-907a-4490-af57-411089ae0e73
Kuprov, Ilya
bb07f28a-5038-4524-8146-e3fc8344c065

Suturina, Elizaveta, Mason, Kevin, Geraldes, Carlos F.G.C., Chilton, Nicholas F., Parker, David and Kuprov, Ilya (2018) Lanthanide‐induced relaxation anisotropy. Physical Chemistry Chemical Physics, 2018 (20), 17676-17686. (doi:10.1039/C8CP01332B).

Record type: Article

Abstract

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. Here we show experimentally 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: (a) that magnetic susceptibility anisotropy can be of the same order of magnitude as the isotropic part (contradicting the unstated assumption in Guéron‘s theory of the Curie relaxation process), and (b) 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). These factors go beyond the well researched cross-correlation effects; they alter the relaxation theory treatment and make strong angular dependencies appear in the nuclear spin relaxation rates. Those dependencies are impossible to ignore – this is now demonstrated both theoretically and experimentally, and suggests that a major revision is needed of the way lanthanide-induced relaxation data are used in structural biology.

Text
manuscript - Accepted Manuscript
Download (1MB)

More information

Accepted/In Press date: 6 June 2018
e-pub ahead of print date: 8 June 2018

Identifiers

Local EPrints ID: 422474
URI: https://eprints.soton.ac.uk/id/eprint/422474
ISSN: 1463-9076
PURE UUID: 3c5cfb0d-dc31-47db-b331-2f7d6213ea5e
ORCID for Ilya Kuprov: ORCID iD orcid.org/0000-0003-0430-2682

Catalogue record

Date deposited: 24 Jul 2018 16:30
Last modified: 15 Aug 2019 04:09

Export record

Altmetrics

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of https://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×