# EUROISMAR 2019

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

## Instruments and methods for NMR PRE relaxivity studies up to 1.4 GHz/33 T of MRI contrast agents based on high-spin lanthanide coordination clusters

Not scheduled
4h
Harnack House and Henry Ford Building

Board: 245
Poster

### Speaker

Steffen Krämer (Laboratoire National des Champs Magnétiques Intenses, LNCMI-CNRS (UPR3228), EMFL, UGA, UPS, and INSA, Grenoble, France)

### Description

In Nuclear Magnetic Resonance (NMR), magnetic field dependent phenomena attract considerable interest: Paramagnetic relaxation enhancement (PRE) is theoretically, experimentally and from the application point of view an important research area, always looking for new relaxation agents with specific properties especially at high magnetic fields and for improved understanding of the PRE mechanisms. Contrast enhancement by PRE in magnetic resonance imaging (MRI) for medicine and material science results in an improved contrast in an image. Recently, paramagnetic coordination clusters, shortly abbreviated as Ln$_{30}$Co$_8$, have been synthesized. They are based on spin-coupled 3d and 4f rare earth paramagnetic centers and exhibit highly interesting PRE properties. An essential point is that the molecular size of the clusters closes the gap between small molecules as nitrides and the larger (super-) paramagnetic nanoparticles applied for example in the context of hyperthermia. The fundamental mechanisms for the observed PRE effect are still under discussion.

The investigation of the PRE properties of these compounds requires - additionally to the conventional NMR fields - ultra-high magnetic fields above the actual limit of superconducting magnets of 23.5 T. These fields are up to now only available at a few specialized high field facilities liking the LNCMI operating resistive magnets up to 37 T at 24 MW electrical power. However, as these magnets exhibit limited stability and homogeneity, their NMR applications are so far mostly limited to solid state physics. In our contribution, we demonstrate the feasibility of PRE studies on liquids in such magnets despite their limitations. We will particularly focus on instruments (broadband tunable NMR probes) and methods (single scan NMR, deconvolution techniques, IR and CPMG sequences) that allow efficient PRE studies from 800 MHz to 1.4 GHz as shown by studies involving new ultrahigh-spin clusters.

### Primary authors

Steffen Krämer (Laboratoire National des Champs Magnétiques Intenses, LNCMI-CNRS (UPR3228), EMFL, UGA, UPS, and INSA, Grenoble, France) Gisela Guthausen (Karlsruhe Institute of Technology (KIT), MVM-VM and EBI-WCT, Karlsruhe, Germany) Masooma Ibrahim (KIT, Institute of Inorganic Chemistry) Nicolas Schork (KIT, MVM-VM and EBI-WCT) Annie Powell (KIT, Institute of Nanotechnology (INT) and Institute of Inorganic Chemistry) Banan Kerdi (LNCMI-CNRS) Audrey Zoulim (LNCMI - CNRS)

### Presentation Materials

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