Mechanochemistry: a unique opportunity for oxygen isotopic labelling and NMR spectroscopy

Informations projet

MISOTOP

N° de convention de subvention: 772204

DOI

10.3030/772204

Projet clôturé

Date de signature de la CE 9 Février 2018

Date de début 1 Octobre 2018

Date de fin 31 Decembre 2024

Financé au titre de

• EXCELLENT SCIENCE - European Research Council (ERC)

Coût total

€ 1 999 836,00

Contribution de l’UE

€ 1 999 836,00

Coordonné par

CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE CNRS
France

Periodic Reporting for period 4 - MISOTOP (Mechanochemistry: a unique opportunity for oxygen isotopic labelling and NMR spectroscopy)

Période du rapport: 2023-04-01 au 2024-12-31

Résumé du contexte et des objectifs généraux du projet

Oxygen is everywhere. In mass, it is the most abundant element at the surface of our planet, and the 3rd most abundant in the Universe. It is a major component of both living organisms and inert matter, and is present in all states of matter (solid, liquid or gas).
At the atomic scale, oxygen can be found in many different bonding environments. Yet, the details on how it binds to other atoms are still not fully understood, and there are many molecules and materials in which its local environment is still unknown. This is an obstacle which needs to be overcome, so that we can to develop a more complete understanding of the structure and properties of a variety of systems around us (whether living or inert). For example, it could help us learn more about the structure of bone, and thereby help develop more efficient treatments for bone repair and regeneration.

The overall purpose of this project was to develop new tools for studying the local vicinity of oxygen in molecules and in materials. This was achieved by implementing novel and robust ways of labeling oxygen atoms in oxygen-17. Indeed, oxygen-17 is a rare form of the oxygen element, which is very sensitive to magnetic fields, and can be used as a "spy" to study chemical bonds in molecules and materials thanks to a technique referred to as "magnetic resonance". However, because it is so rare, molecules and materials need to be labeled by this atom. Up until recently, this was very difficult and expensive to achieve for chemists. In our project, a large part of the work consisted in developing oxygen-17 labeling protocols using a synthetic approach called "mechanochemistry". This enabled us to label for the first time a wide diversity of compounds in a cost-efficient, environmentally friendly, and user friendly way. Some of these compounds were then used to perform advanced analyses by magnetic resonance, and thereby gain unprecedented insight into the structure and dynamics within biological minerals (like those related to bone or kidney stones), and, more recently, on materials related to studies on carbon capture.

On the long run, it is expected the developments made in the course of our studies on new routes for oxygen-17 labeling will be useful to help undertand better the structure and functionalities of many systems.

Travail effectué depuis le début du projet jusqu’à la fin de la période considérée dans le rapport et principaux résultats atteints jusqu’à présent

Information on the local vicinity of oxygen in molecules and materials can be obtained by looking at one of its stable isotopes, oxygen-17. Indeed, this isotope can be "manipulated" using magnetic fields, with a technique called "nuclear magnetic resonance" (NMR). However, because oxygen-17 is poorly abundant on Earth (representing only ~ 0.04% of all oxygen atoms), it is very difficult to detect.

To counter this issue, in this project, we have worked on the development of new rapid, user-friendly and low-cost protocols for enriching in oxygen-17 a wide variety of compounds, so that their oxygen-17 signal can be detected by NMR. These have included
* key families of organic molecules, such as fatty acids (like oleic acid) and amino acids (like glycine)
and
* common families of minerals, like calcium phosphates (related to bone), as well as oxides like silica and titania.
The technique we have been using for the enrichment is "mechanochemistry", and more specifically "ball-milling". We have shown that this method is highly efficient for these applications. More importantly, it is the first time that this environmentally-friendly method was used for oxygen isotopic labeling.

Thanks to the newly-available enriched molecules and materials, we have been able to push forward the developments in oxygen-17 NMR spectroscopy, allowing it to be used in the study of a wider range of chemical bonds. Moreover, with this technique, we investigated in detail the structure and properties of several nanomaterials and biomaterials. One case-study concerned nanoparticles like those found in some sunscreens: thanks to the oxygen-17 labeling, we were able to learn new aspects about their evolution under UV-irradiation (by "looking" specifically at the surface of the nanoparticles), which is important for their future applications. Other case studies concerned minerals related to bone (calcium phosphates) and kidney stones (calcium oxalates), in which we were able to highlight different types of dynamics around within the minerals. Towards the end of the project, applications to the study of carbonate phases of interest for carbon capture were also looked into.

Results of the research performed were disseminated to a broad scientific community through research publications (all made available in open-access), oral and poster presentations at conferences, and seminars. Moreover, two training schools were organised in our laboratory in Montpellier, to teach the next generation of chemists how to perform the 17O-labeling using mechanochemistry. Importantly, following our work, several research groups have already started to follow our footsteps, by taking up similar enrichment approaches. This implies that longer-term perspectives can be expected to stem from this project in the years to come.

Progrès au-delà de l’état des connaissances et impact potentiel prévu (y compris l’impact socio-économique et les conséquences sociétales plus larges du projet jusqu’à présent)

The oxygen-17 enrichment procedures we have established over the years have opened new avenues for the use of oxygen-17 NMR by a broad variety of chemists. Indeed, for each new molecule or compound, we have endeavoured to establish protocols which are fast, user-friendly, safe, and low-cost, so that they can become widely picked-up and used not only in research labs, but also in teaching labs. Thus, by making the procedures accessible and attractive to a wide community of chemists, oxygen-17 NMR is now becoming one of the options to consider by chemists, when trying to analyze and understand the structure and functionalities of challenging systems.

Using the newly-developed 17O-labeling protocols, we have already helped push the boundaries of what can be learnt about the structure and properties of a wide variety of (bio)molecules and functional materials using magnetic resonance. For example, we have been able to analyze in detail, for the first time, the structure around oxygen atoms in minerals related to bone, by looking at both the core and surface of this mineral. Such levels of insight had never been reached before, and this could be of use to help develop better knowledge on how bone is made, and, as a consequence, better cures for treating bone-diseases. More recently, investigations have concerned analyzing materials developed for carbon capture, for which oxygen-17 NMR is also a very valuable probe.

Last but not least, it is worth noting that beyond the oxygen-17 labeling and NMR aspects, this project also contributed to the development of mechanochemistry as a synthetic technique, by proposing new tools for monitoring ball-milling reactions in real time, and new ways of heating the reaction medium. This implies that a broader long-term impact of the studies on the chemistry research community can be expected.

From oxygen-17 labeling to elucidating the structure of complex (bio)materials