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The 20 minutes website has also communicated on our article in The Conversation.

Des aimants légers et performants grâce à la chimie moléculaire

Les aimants sont des matériaux présents dans de très nombreux objets de nos vies quotidiennes: ce sont par exemple des constituants essentiels de nos ordinateurs, des microphones, des moteurs électriques d’appareils ménagers ou même de turbines d’éoliennes. Pour certaines applications, comme dans les smartphones ou les satellites, ces aimants doivent être à la fois légers et de petite taille.

Les aimants sont généralement des solides constitués de métaux purs, d’oxydes métalliques ou d’alliages métalliques. Malgré leur utilisation intensive et leur énorme succès dans les applications technologiques, la production d’aimants pose des problèmes environnementaux et économiques. Certains éléments chimiques nécessaires à leur élaboration, comme les terres rares présents dans les aimants les plus puissants connus aujourd’hui, sont inégalement répartis sur la planète ou difficiles à isoler. De plus, la fabrication des aimants nécessite souvent des procédés réalisés à haute température qui consomment beaucoup d’énergie.

Afin de remédier à ces problèmes, les scientifiques essayent depuis environ 3 décennies de créer un nouveau type d’aimants en assemblant des molécules pour créer un édifice aux propriétés désirées. L’élaboration de tels assemblages moléculaires se fait à température ambiante, ce qui rend leur fabrication facile à reproduire et peu coûteuse. Cependant, il y a encore quelques mois, les performances des aimants moléculaires (température de fonctionnement, capacité d’attraction…) étaient encore très loin de celles des aimants conventionnels.

Récemment, dans une étude publiée dans Sciencenous avons démontré qu’il est désormais possible d’obtenir des aimants moléculaires avec des caractéristiques comparables aux aimants conventionnels….

See Full text…

Rodolphe Clérac, Research Director at the Centre de Recherche Paul and head of the “Molecular Materials & Magnetism” team, received the 2021 Silver Medal from the CNRS. In 2000, he joined the IUT of Bordeaux 1 and the Centre de Recherche Paul Pascal, as an associate professor. He began his career focusing on the physical properties of fullerene salts and new molecular materials. In 2001, he brought together a new research team around molecular magnetic materials and introduced coordination chemistry at the Centre de Recherche Paul Pascal.

Photo © Philippe Labeguerie

In 2002, he discovered the first single-chain magnets, which opened up a new research field in molecular magnetism. His work then focused on these new one-dimensional magnets, the organization of molecule-magnets into coordination networks and he widened his researches towards bi- and tri-stable molecule-based systems with intramolecular electron transfer or spin conversion in solution, in the solid state or liquid crystal phases. In 2008, he joined the CNRS becoming a full-time researcher, and then in 2013, he was promoted to research director. In 2020, he developed a new post-synthetic approach and obtain the first molecular magnets operating up to 242°C with a high coercivity at room temperature. This synthetic strategy offers broad prospects for the preparation of a new generation of lightweight magnets at high temperature. His projects are currently directed towards the synthesis of new multifunctional molecule-based materials containing redox-active sites in order to obtain high-performance magnets also possessing high electrical conduction, photoactivity or porosity allowing selective gas absorption.

Rodolphe Clérac is author and co-author of over 500 publications and has presented over 130 invited lectures. He was elected in 2019 to the European Academy of Sciences and in 2020 to the Academia Europaea. In 2014, he became a junior distinguished member of the Société Chimique de France and received various awards including in 2017 the France-Berkeley Fund Award, in 2014 the National Chinese Award for the “1000 Talents Program” and in 2009 the Young Researcher Award of the Division de Chimie Physique de la Société Chimique de France.

Contact: Rodolphe Clérac
Centre de Recherche Paul Pascal, UMR CNRS 5031
“Molecular Materials & Magnetism” team
115 Avenue du Dr. A. Schweitzer, 33600 Pessac, FRANCE
Phone: +33 (0) 5 56 84 56 50

Substantial π-aromaticity in the anionic heavy-metal cluster [Th@Bi12]4−“, A.R. Eulenstein, Y.J. Franzke, N. Lichtenberger, R.J. Wilson, H. Lars Deubner, F. Kraus, R. Clérac, F. Weigend and S. Dehnen, Nature Chemistry, 13, 149-155, (2021) – 10.1038/s41557-020-00592-z – hal-03133022

See below different links, which discuss this work:

In English:

https://chemistrycommunity.nature.com/

https://www.chemistryworld.com

In German:

https://idw-online.de/

https://www.uni-marburg.de/

http://marburg.news/

https://www.juraforum.de/

Science

Metal-organic magnets with large coercivity and ordering temperatures up to 242°C”, Science, Vol. 370, Issue 6516, pp. 587-592, (2020) – 10.1126/science.abb3861Abstract – Reprint Full text

Lightening the load by Jake Yeston – 10.1126/science.370.6516.543-e

Des aimants légers et performants grâce à la chimie moléculaire” by C. Mathonière and R. Clérac, The Conversation, 11th April 2021 – link

See below other links (167), which discuss our work (in 19 different languages):

Towards next-generation molecule-based magnets

Magnets are to be found everywhere in our daily lives, whether in satellites, telephones or on fridge doors. However, they are made up of heavy inorganic materials whose component elements are, in some cases, of limited availability.

Now, researchers from the CNRS, the University of Bordeaux and the ESRF (European Synchrotron Radiation Facility in Grenoble) have developed a new lightweight molecule-based magnet, produced at low temperatures, and exhibiting unprecedented magnetic properties. This compound, derived from coordination chemistry, contains chromium, an abundant metal, and inexpensive organic molecules.  This is the first molecule-based magnet that exhibits a ‘memory effect’ (i.e. it is capable of maintaining one of its two magnetic states) up to a temperature of 240°C. This effect is measured by what is known as a coercive field, which is 25 times higher at room temperature for this novel material than for the most efficient of its molecule-based predecessors.  This property therefore compares well with that of certain purely inorganic commercial magnets. The discovery, published on 30 October in Science, opens up highly promising prospects, which could lead to next-generation magnets complementary to current systems.

Reference & authors: P. Perlepe, I. Oyarzabal, A. Mailman, M. Yquel, M. Platunov, I. Dovgaliuk, M. Rouzières, P. Négrier, D. Mondieig, E. A. Suturina, M.A. Dourges, S. Bonhommeau, R. A. Musgrave, K. S. Pedersen, D. Chernyshov, F. Wilhelm, A. Rogalev, C. Mathonière, R. Clérac, Metal-organic magnets with large coercivity and ordering temperatures up to 242°C”, Science, Vol. 370, Issue 6516, pp. 587-592, (2020) – 10.1126/science.abb3861Abstract – Reprint Full text

Online comments and publications

Acknowledgments: This work was supported by the University of Bordeaux, the Région Nouvelle Aquitaine, Quantum Matter Bordeaux, the Basque Government, the University of the Basque Country, the Villum Fonden, the University of Jyväskylä, the Academy of Finland, the Centre National de la Recherche Scientifique (CNRS) and the ESRF-The European Synchrotron.

Contact: clerac@crpp-bordeaux.cnrs.fr

ACAMEMIA EUROPAEA

What is the Academia Europaea?

The object of Academia Europaea is the advancement and propagation of excellence in scholarship in the humanities, law, the economic, social, and political sciences, mathematics, medicine, and all branches of natural and technological sciences anywhere in the world for the public benefit and for the advancement of the education of the public of all ages in the aforesaid subjects in Europe.

Academia Europaea is a European, non-governmental association acting as an Academy. Our members are scientists and scholars who collectively aim to promote learning, education and research. Founded in 1988, with about 3800 members which includes leading experts from the physical sciences and technology, biological sciences and medicine, mathematics, the letters and humanities, social and cognitive sciences, economics and the law.

https://www.ae-info.org/ae/Member/Clerac_Rodolphe

This study reports the first transition metal compounds featuring mixed fluoride–cyanide ligands. A significant enhancement of the magnetic anisotropy, as compared to the pure fluoride ligated compounds, is demonstrated by combined analysis of high-field electron paramagnetic resonance (HF-EPR) spectroscopy and magnetization measurements.

What did scientists discover?

This study reports the first transition metal molecules featuring both fluorine and cyanide ligands (see “branches” attached to the metal atom (M) in the molecules at the top of the figure). A strong and significant enhancement of the non-uniformity of the magnetism, the “magnetic anisotropy” for the trans-[ReIVF4(CN)2]2– complex (shown in the upper right) was discovered by combined high-field magnetization and electron paramagnetic resonance (EPR) spectroscopy (see lower Figure).

Why is this important?

This research highlights an efficient new strategy for synthesizing molecular building blocks based on heavier transition metals that feature relatively large magnetic moments and very strong magnetic anisotropy. Such building blocks may form the basis for future high-performance magnetic materials used in high-density information storage applications.

Read more on MagLab website:

https://nationalmaglab.org/user-facilities/emr/emr-publications/highlights-emr/molecular-magnetic-building-blocks

About the European Academy of Sciences (EURASC) :

“The European Academy of Sciences (EURASC) is a non-profit non-governmental, independent organization of the most distinguished scholars and engineers performing forefront research and the development of advanced technologies, united by a commitment to promoting science and technology and their essential roles in fostering social and economic development. One of the most important objectives of the Academy is the promotion of fundamental research and excellence in science and technology. The EURASC aims to recognize and elect to its membership the best European scientists with a vision for Europe as a whole, transcending national borders both in elections and in actions, and with the aims of strengthening European science and scientific cooperation and of utilizing the expertise of its members in advising other European bodies in the betterment of European research, technological application and social development.”

https://www.eurasc.org/new-members

https://www.eurasc.org/user/725/rod…

Contact :

Rodolphe Clérac

Centre de Recherche Paul Pascal, UMR CNRS 5031
115 Avenue Schweitzer, 33600 Pessac, FRANCE
Phone : +33 (0) 5 56 84 56 50

Dr. Xiaozhou Ma received one of two prizes for the best poster presented at the 7th European Conference on Molecular Magnetism which took place in Florence, Italy, the 15th-18th of September 2019.

https://www.ecmm2019.org/

The title of her poster was “Magnetic Exchange Coupling Promotion in Dinuclear Compounds with Redox-active Ligand”.

Xiaozhou Ma was a PhD student of P. Dechambenoit and R. Clérac who defended on the 11th of September 2019.

Rodolphe Clérac’s research has been recently cited by the CNRS Institute of Chemistry.  

L’origine du magnétisme atypique de l’ion actinide Uranium(IV) enfin comprise

Les ions de terres rares et d’actinides, qui présentent des propriétés magnétiques remarquables étant données leurs structures électroniques, sont de bons candidats pour entrer dans la composition des aimants de nouvelle génération. Mais alors pourquoi, de manière atypique, l’uranium au degré oxydation IV n’est que faiblement magnétique, alors qu’au regard de sa structure électronique, ses propriétés devraient être comparables aux autres analogues de terres rares ou d’actinides?

Read the rest of the article here

In partial fulfillment of the requirements for a posthumous PhD diploma for Angela Valentin, a thesis defense of her work will take place in the CRPP amphitheatre on 11 December 2019 at 14h.

In attendance will be the jury consisting of Jeanne Crassous (Institut des Sciences Chimiques de Rennes), Lorenzo di Bari (University of Pisa), Jérôme Lacour (Univeristy of Geneva), and Cécile Zakri (University of Bordeaux).

The presentation will be delivered by E. Hillard and P. Rosa..

Friends and family are cordially invited to attend this commemoration of Angela’s work.

Dans le cadre de l’Idex de l’Université de Bordeaux, Guillaume Naulet, a reçu le prix de thèse “Sciences et Technologie”.
Guillaume a effectué sa thèse au CRPP de 2015 à 2018, sous la direction de Fabien DUROLA et Harald BOCK, dans l’équipe M3.

Son travail concernait le développement de techniques de protection pour la synthèse de larges arènes polycycliques par réaction de Perkin, ce qui a notamment permis de former des rubans de Möbius moléculaires.

https://www.u-bordeaux.fr/Actualites/De-la-recherche/Quatre-docteurs-recompenses-par-le-Prix-de-these-2019

Des molécules aromatiques et torsadées

Fabien Durola's work featured in l'Actualité Chimique

“La chimie organique est régie par de nombreuses règles
établies au fil des expériences. Aujourd’hui, les chimistes
explorent les limites de ces lois. Comme Fabien Durola et son
équipe du Centre de recherche Paul Pascal (CNRS/Université
de Bordeaux), qui prouvent avec leur cyclo-tris-[5]hélicène
qu’un composé aromatique peut être triplement torsadé,
esthétique et atypique, de par ses propriétés électroniques
induites.”

Read more (in French)

The Magnetism Network of the Greater Region won the 2018 interregional research prize for its collaborative fundamental research and R&D activities. Congratulations to the coordinator of this organizion, Thomas Hauet. Let’s wish the same success to the French and European Magnetometry Network!

Members of the European Magnetism Network win 2018 Interregional research prize

http://magnetometry.cnrs.fr/

http://magnetometry.cnrs.eu/

This work demonstrates the possibility of modulating the spin state of the FeII sites and subsequently the magnetic properties of a [2×2] FeII grid-like complex by variation of the degree of deprotonation of the hydrazine-based N-H sites of the ligand in the complex. Evidence has been provided, both in the solid state and in solution, towards understanding the strong influence of the spin-crossover process on the pKas of the grid ligands, which exhibit a unique deprotonation pattern. The present study provides a demonstration of the effect of spin state switching of a chemical property, here on ligand pKa in a metallosupramolecular grid.

modulating the spin state of the FeII sites and subsequently the magnetic properties of a [2x2] FeII  grid-like complex

Sébastien Dhers, Abhishake Mondal, David Aguilà, Juan Ramírez, Sergi Vela, Pierre Dechambenoit, Mathieu Rouzières, Jonathan R. Nitschke, Rodolphe Clérac & Jean-Marie Lehn. Spin State Chemistry: Modulation of Ligand pKa by Spin State Switching in a [2×2] Iron(II) Grid-Type Complex J. Am. Chem. Soc. 2018, 140 (26), pp 8218–8227 DOI : 10.1021/jacs.8b03735

See also the Institut de Chimie website of the CNRS

Incorporating functional molecules into sensor devices is an emerging area in molecular electronics that aims at exploiting the sensitivity of different molecules to their environment and turning it into an electrical signal. Among the emergent and integrated sensors, microelectromechanical systems (MEMS) are promising for their extreme sensitivity to mechanical events. However, to bring new functions to these devices, the functionalization of their surface with molecules is required. Herein, we present original electronic devices made of an organic microelectromechanical resonator functionalized with switchable magnetic molecules. The change of their mechanical properties and geometry induced by the switching of their magnetic state at a molecular level alters the device’s dynamical behavior, resulting in a change of the resonance frequency. We demonstrate that these devices can be operated to sense light or thermal excitation. Moreover, thanks to the collective interaction of the switchable molecules, the device behaves as a non-volatile memory. Our results open up broad prospects of new flexible photo- and thermo-active hybrid devices for molecule-based data storage and sensors.

Incorporating functional molecules into sensor devices is an emerging area in molecular electronics

Matias Urdampilleta, Cedric Ayela, Pierre-Henri Ducrot, Daniel Rosario-Amorin, Abhishake Mondal, Mathieu Rouzières, Pierre Dechambenoit, Corine Mathonière, Fabrice Mathieu, Isabelle Dufour et Rodolphe Clérac
Molecule-based microelectromechanical sensors
Scientific Reports – Mai 2018
DOI: 10.1038/s41598-018-26076-2

See also the Institut de Chimie website of the CNRS

Stephanie Beach (Boston University - Doerrer's group) won a Chateaubriand Fellowship to join our group

Stephanie Beach, of the Doerrer Group (Boston University), recently won a prestigious Chateaubriand Fellowship. The Chateaubriand Fellowship is a grant offered by the Embassy of France in the United States. It supports outstanding Ph.D. students from American universities who wish to conduct research in France for a period ranging from 4 to 9 months. Chateaubriand fellows are selected through a merit-based competition, through a collaborative process involving expert evaluators in both countries.

The program is divided into two subprograms: Humanities and Social Sciences (HSS) which supports those who seek to study Humanities and Social Sciences. Stephanie was awarded the Chateaubriand Fellowship in Science, Technology, Engineering, Mathematics & Biology-Health (STEM), which is for doctoral students who aim to initiate or reinforce collaborations, partnerships or joint projects between French and American research teams. This fellowship is offered by the Office for Science & Technology (OST) of the Embassy of France in partnership with American universities and French research organizations such as CNRS, Inserm and Inria.

Stephanie is currently working at the Centre de Recherche Paul Pascal, a CNRS lab, in Bordeaux, France from February through May of 2018 to partner with the group of Prof. Rodolphe Clérac. She is developing new variations of the Doerrer group thiocarboxylate lantern complexes for development as single molecule magnets.

Congratulations Stephanie!

http://www.bu.edu/chemistry/2018/03/28/stephanie-beach-of-the-doerrer-group-wins-prestigious-chateaubriand-fellowship/


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