Project

Back to overview

Homo-Fluorinated Paramagnetic Metal Complexes and Ionic Liquids for the Application in MRI Field Probe Devices

English title Homo-Fluorinated Paramagnetic Metal Complexes and Ionic Liquids for the Application in MRI Field Probe Devices
Applicant Alberto Roger
Number 155996
Funding scheme Project funding (Div. I-III)
Research institution Institut für Chemie Universität Zürich
Institution of higher education University of Zurich - ZH
Main discipline Inorganic Chemistry
Start/End 01.01.2015 - 31.12.2017
Approved amount 193'285.00
Show all

Keywords (6)

Magnetic Resonance Imaging; Nuclear Magnetic Resonance; Ionic Liquids; Fluorinated Ligands; Paramagnetic complexes; Field Probe Device

Lay Summary (German)

Lead
“Magnetic Resonance Imaging”, besser bekannt als MRI, ist eine der wichtigsten Methoden in der diagnostischen Medizin. Damit hochaufgelöste Bilder entstehen, müssen Inhomogenitäten im Magnetfeld genau und dynamisch, das heisst während der Messung, bekannt sein. Das Magnetfeld wird mit Sonden ausgemessen. Diese enthalten paramagnetische Metallkomplexe und Substanzen mit möglichst vielen, chemisch gleichwertigen Fluorid-Ionen. Diese Mischung muss gewisse physikalisch-chemische Bedingungen erfüllen, um den Ansprüchen der Diagnostik zu genügen. Bis heute sind keine idealen Sonden verfügbar. In diesem Projekt erforschen und entwickeln wir sogenannte ionischen Flüssigkeiten, welche eine sehr hohe Fluordichte haben und in denen paramagnetische Komplexe lösbar sind. Das Ziel des Projektes sind neue Sonden für MRI welche optimale physikalische Parameter haben, nicht toxisch sein sollten und zudem über lange Zeitdauer eingesetzt werden können.
Lay summary

Magnetic Resonance Imaging (MRI) is a pivotal modality in medical diagnostics. To move MRI towards faster and quantitative imaging, the magnetic field dynamics used for MR image encoding must be known with great accuracy. This is provided by magnetic field monitoring based on fluorine NMR field probes. Currently available fluorine compounds do not have short enough relaxation times in combination with the required sensitivity (nucleus density), resulting in insufficient monitoring bandwidth. Probes that overcome this limitation must meet a number of physical and application-related parameters; i) high 19F nuclei density, ii) single 19F resonance (all 19F magnetically equivalent), iii) T1 ≈ T2< 200 μs, iv) ability to confine in capillaries and v) long-term chemical stability and low toxicity. To match these requirements for a useful probe, we will synthesize ionic liquids (IL) with highly homo-fluorinated anions or cations, dissolve paramagnetic complexes and assess the parameters of such solutions. To address the question of very high 19F density, new homo-perfluorinated compounds such as [C(CF3)5]- (CpF*) will be prepared. Alteration of cations alters viscosity and solubility of the paramagnetic substances. Furthermore, we will focus on ions comprising the perfluorinated tert-Bu (tbuF*) fragment. This first approach is based on ILs as 19F carriers. In parallel, complexes of paramagnetic cations with homo-perfluorinated ligands will be synthesized. Ionic complexes will directly lead to ILs with appropriate counter-ion choice; neutral complexes are highly soluble in non-polar solvents. It is the objective of this study to obtain an ultimate compound which overcomes the deficiencies of current NMR field probes.

Direct link to Lay Summary Last update: 03.10.2014

Responsible applicant and co-applicants

Employees

Publications

Publication
Ultra-fast Ligand Self-Exchanging Gadolinium Complexes in Ionic Liquids for NMR Field Probes
Looser Anna Christina, Barmet Christoph, FoxThomas, Blacque Olivier, Gross Simon, Nussbaum Jennifer, Prüssmann Klaas, Alberto Roger, Ultra-fast Ligand Self-Exchanging Gadolinium Complexes in Ionic Liquids for NMR Field Probes, in Inorganic Chemistry.

Collaboration

Group / person Country
Types of collaboration
Institute for Biomedical Engineering, ETH Zurich Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
- Exchange of personnel

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
Swiss Chemical Society Fall Meeting 2017 Talk given at a conference Gadolinium Complexes Exhibiting Ultra-fast Ligand Self-exchange in Ionic Liquids for Application in NMR Field Probes 21.08.2017 Bern, Switzerland Alberto Roger; Looser Anna Christina;
Swiss Chemical Society Fall Meeting 2016 Poster Highly Homo-perfluorinated Paramagnetic Ionic Liquids for NMR Field Probes for Magnetic Field Monitoring in MRI 15.09.2016 University of Zurich, Switzerland Alberto Roger; Looser Anna Christina;
Swiss Chemical Society Fall Meeting 2015 Poster Highly Homoperfluorinated Ionic Liquids for NMR Field Probes for Magnetic Field Monitoring in MRI 04.09.2015 EPFL, Switzerland Alberto Roger; Looser Anna Christina;


Abstract

This joint project between groups from Chemistry at UZH and Biomedical Engineering at ETHZ aims at the study of solutions, consisting of i)highly fluorinated ionic liquids and paramagnetic metal complexes or ii)paramagnetic complexes carrying highly fluorinated ligands and non-fluorinated ionic liquids, respectively. The ultimate objective is an NMR field probe which contains one of these combinations, suitable for the real-time monitoring of the spatiotemporal magnetic field evolution in MRI scanners. An important research challenge to be tackled in this project is the request for homo-(per)fluorinated ligands or ionic liquids (ILs). “Homo” in this context means, equivalent fluorines, an important property for NMR magnetometry. Very high solubilities are a central aspect. The chemical part of the study aims therefore at solutions which contain exclusively magnetically equivalent fluorines, present in the complex or in one of the ions of the IL. Furthermore, from a physical point of view, the compounds and solutions to be developed must fulfill well defined, quantifiable parameters in order to be applicable in NMR field probes for MRI field monitoring. The most important parameters are; single fluorine resonance, high density in fluorine (>30 M), relaxation times T1 ? T2 < 200 ?sec, chemical stability and low viscosity. ILs are preferred as solvents since they are non-volatile and their solubility properties can conveniently be fine-tuned. Taking these restrictions as benchmarks, the question for useful solutions of paramagnetic complexes in ILs for applicable devices in MRI instruments remains unsolved so far. Whereas fluorinated ionic liquids or paramagnetic complexes with fluorinated ligands are not new, the scientific challenge of the project consists in the design of new complex/IL combinations, which fulfill these physico-chemical requirements.Aiming at highly homo-fluorinated IL, perfluorinated “Cp*” ([C5(CF3)5]-) is a main focus and also anions such as [Al(OC(CF3))4]- will be included. Fluorinated imidazolium and phosphonium cations with non-fluorinated anions complement this series. Dissolution studies of small, paramagnetic complexes will allow for a systematic exploration of their physico-chemical properties. These ILs will be further derivatized, pushing for increased ability to dissolve polar or even charged complexes. For obtaining a deeper insight into the coordination chemistry of ligands with strongly electron withdrawing groups, complexes with the [C5(CF3)5]- ligand will be explored.The second approach consists in the preparation of paramagnetic complexes, comprising homo-fluorinated ligands soluble in appropriate ILs. We will use small ligand frameworks, derivatized with equivalent -CF3 groups. Ligands will be based on acac and other, symmetrical bi- or tridentate scaffolds. These complexes will be studied for their dissolution in non-fluorinated ILs and for the required physico-chemical parameters.All newly prepared compounds will be subjected to magnetic properties studies, initially in standard high-resolution NMR spectrometers at UZH, then in MRI scanners at ETHZ. The most suitable solutions will be used for the preparation of actual field probes. The project thus embraces synthetic organic and inorganic chemistry and all physical methods for a complete characterization of parameters of new complexes and ILs respectively. Theoretical calculations will be included in order to understand the properties on a molecular level.
-