Dr. Daniel J. Cutler (Marie SkłodowskaCurie Actions Global Postdoctoral Fellow

LabMolDesign / Rawson Group ; Universitat de Barcelona / University of Windsor )

Résumé : The field of molecular magnetism focuses on the development of magnetic materials by the utilization of the so-called “bottom-up” approach, using paramagnetic building blocks to prepare new materials with desirable magnetic properties.^1,2 Some common choices of building blocks include transition metal (TM) and lanthanide (Ln) ions, and open-shell radicals. The combination of these starting materials into different architectures can tune the magnetic properties of the material to afford sought after magnetic properties ranging from slow magnetic relaxation dynamics, spin crossover behaviour, magnetic frustration and high-spin bearing species. This seminar will present work based on two themes, TM and Ln coordination cluster chemistry and main group thiazyl radical chemistry.

Polymetallic coordination clusters are some of the most well studied magnetic molecules with the dodecametallic Mn₁₂-acetate cluster being the first reported Single Molecule Magnet (SMM).³ Here we present work building cluster compounds with TM ions (Cu^II and Fe^III) and Ln ions (Dy^III, Tb^III and Gd^III) using flexible pyridyl alkoxide ligands. The Cu^IILn^III butterfly system displays a “switching on” effect where the addition of auxiliary un-paired spins, in the form of Cu^II, switches on the slow magnetic relaxation of the molecule. Work with Fe^III ions focuses on the effects on cluster preparation when using chiral vs racemic chelates. We report a family of six cluster compounds ranging from a simple Fe₂ dimer to a Fe₁₀ decamer.

Main group thiazyl radicals have proven to be promising candidates for designing tuneable magnetic materials. To date work with these radicals have afforded material with properties varying from canted anti-ferromagnetism,⁴ single molecule magnetism⁵ and spin crossover.⁶ The 4- pyDTA radical, presented, displays hysteric spin crossover behaviour in the solid state as a result of a first order phase transition. Investigations with variable temperature EPR, magnetometry and XRD methods elucidate the nature of this transition

References:

1.- M. B. Duriska, S. M. Neville, B. Moubaraki, J. D. Cashion, G. J. Halder, K. W. Chapman, C. Balde, J.-F. Létard, K. S. Murray, C. J. Kepert and S. R. Batten, Angewandte Chemie International Edition, 2009, 48, 2549–2552.

2.-  S. Sanz, H. M. O’Connor, E. M. Pineda, K. S. Pedersen, G. S. Nichol, O. Mønsted, H. Weihe, S. Piligkos, E. J. L. McInnes, P. J. Lusby and E. K. Brechin, Angewandte Chemie International Edition, 2015, 54, 6761–6764.

3.- H. J. Eppley, H.-L. Tsai, N. de Vries, K. Folting, G. Christou and D. N. Hendrickson, Journal of the American Chemical Society, 1995, 117, 301–317.

4.-  D. Leckie, M. Harb, N. Mroz, J. D. Wrixon, J. Campo, A. Arauzo, H. Bakhshi, M. Pilkington and J. M. Rawson, J. Am. Chem. Soc., 2024, 146, 31371–31376.

5.- E. M. Fatila, M. Rouzieìres, M. C. Jennings, A. J. Lough, R. Clérac and K. E. Preuss, Journal of the American Chemical Society, 2013, 135, 9596–9599.

6.- W. Fujita and  and K. Awaga, Science, 1999, 286, 261–262.

Andrey S. Klymchenko (Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Université de Strasbourg)

Abstract :

Orateur : Christophe COPÉRET  (ETH Zurich, Department of Chemistry and Applied Biosciences)

Résumé : Most efficient chemical processes used in industry rely on heterogeneous catalysis. While the search for more sustainable processes and the changes in environmental policies impose the continuous development of more efficient catalysts, we have currently little understanding of the structure of the actives in these processes. Hence, due to their inherent complexity, heterogeneous catalysts have been mostly developed empirically.

Here, we will show how constructing active sites, one atom at a time on surfaces, enables molecular-level understanding and implementation of rational approaches for the improvement of catalytic processes. We will first illustrate how this approach enables to generate selective single-site catalysts. We will next show how from these isolated (single) sites, one can generate and understand far more complex systems such as supported nanoparticles, where interfaces, alloying… play a critical role. This lecture will be developed around these themes and will show how the development of advanced characterization tools augmented by computational approaches can provide useful information to bridge the gap between fundamental and applied (industrial) catalysis. Furthermore, alternative complementary approaches based on data-driven high-throughput experimentations will be also discussed, paving the way for automated discovery and development of catalysts.

Prof. Galo J. A. A. Soler-Illia ( Instituto de Nanosistemas, Escuela de Bio y Nanotecnologías, Universidad Nacional de General San Martín, San Martín, Argentina )

Abstract (pdf)