Longitudinal and Transverse 1H Nuclear Magnetic Resonance Relaxivities of Lanthanide Ions in Aqueous Solution up to 1.4 GHz/33 T

Rami Nasser Din; Aiswarya Chalikunnath Venu; Thomas Rudszuck; Alicia Vallet; Adrien Favier; Annie K Powell; Gisela Guthausen; Masooma Ibrahim; Steffen Krämer

doi:10.3390/molecules29204956

Longitudinal and Transverse ¹H Nuclear Magnetic Resonance Relaxivities of Lanthanide Ions in Aqueous Solution up to 1.4 GHz/33 T

Molecules. 2024 Oct 19;29(20):4956. doi: 10.3390/molecules29204956.

Authors

Affiliations

¹ Université Grenoble Alpes, LNCMI-EMFL, CNRS, INSA-T, and UPS, CEDEX 9, 38042 Grenoble, France.
² Institute of Nanotechnology, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany.
³ Institute of Mechanical Process Engineering and Mechanics, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany.
⁴ Université Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale (IBS), 38044 Grenoble, France.
⁵ Institute of Inorganic Chemistry, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany.
⁶ Institute for Quantum Materials and Technologies, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany.
⁷ Chair of Water Chemistry and Water Technology, Engler-Bunte-Institut, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany.

Abstract

The longitudinal and transverse nuclear magnetic resonance relaxivity dispersion (NMRD) of ¹H in water induced by the paramagnetic relaxation enhancement (PRE) of dissolved lanthanide ions (Ln³⁺) can become very strong. Longitudinal and transverse ¹H NMRD for Gd³⁺, Dy³⁺, Er³⁺ and Ho³⁺ were measured from 20 MHz/0.47 T to 1382 MHz/32.5 T, which extended previous studies by a factor of more than two in the frequency range. For the NMRD above 800 MHz, we used a resistive magnet, which exhibits reduced field homogeneity and stability in comparison to superconducting and permanent NMR magnets. These drawbacks were addressed by dedicated NMRD methods. In a comparison of NMRD measurements between 800 MHz and 950 MHz performed in both superconducting and resistive magnets, it was found that the longitudinal relaxivities were almost identical. However, the magnetic field fluctuations of the resistive magnet strongly perturbed the transverse relaxation. The longitudinal NMRDs are consistent with previous work up to 600 MHz. The transverse NMRD nearly scales with the longitudinal one with a factor close to one. The data can be interpreted within a PRE model that comprises the dipolar hyperfine interactions between the ¹H and the paramagnetic ions, as well as a Curie spin contribution that is dominant at high magnetic fields for Dy³⁺, Er³⁺ and Ho³⁺. Our findings provide a solid methodological basis and valuable quantitative insights for future high-frequency NMRD studies, enhancing the measurement accuracy and applicability of PRE models for paramagnetic ions in aqueous solutions.

Keywords: lanthanide ions; magnetic field homogeneity; magnetic field stability; nuclear magnetic resonance relaxation dispersion; paramagnetic relaxation enhancement; ultra-high magnetic fields.

Grants and funding

R.N.D. and S.K. acknowledge support by the French National Research Agency in the framework of the “Investissements d’avenir” program (ANR-15-IDEX-02). We acknowledge the support of the LNCMI-CNRS, a member of the European Magnetic Field Laboratory (EMFL), for conducting the research in the resistive magnet. A.K.P. and M.I. acknowledge the German Research Foundation (DFG) Collaborative Research Centre (CRC) 1573 “4f for Future” projects B1 and B4, and the Helmholtz Program “Materials Systems Engineering” (MSE) of Program-oriented Funding phase 4 (PoF IV). A.C.V. acknowledges KIT for the PhD grant and travel grant through the LNCMI-CNRS. The diverse financial support of DFG is highly acknowledged for Pro²NMR @ KIT. The financial support from the IR INFRANALYTICS FR2054 for conducting the research is gratefully acknowledged.