Elucidating the Correlation Between the Redox Potential, Spin State, and Crystal Structure in a Series of Ferrous Complexes with Redox-Active Ligands.

Livia Getzner,  Yasmine Remili,  Zakaria Ziani,  Laure Vendier,  William Nicolazzi,  Aurelian Rotaru,  Haizhu Yu,  Gábor Molnár,  Saioa Cobo,  Azzedine Bousseksou.
Angew. Chem. Int. Ed. 2025, e202506965.
https://doi.org/10.1002/anie.202506965

A series of Fe(II) Hofmann-type clathrates with redox-active ligands reveals a bell-shaped relationship between redox potential and spin crossover temperature.
This work uncovers how electronic ligand tuning modulates spin state, crystal symmetry, and electron transfer, rationalized through Marcus theory.

Contacts:
Saioa Cobo  saioa.cobo@lcc-toulouse.fr
Azzedine Bousseksou azzedine.bousseksou@lcc-toulouse.fr

Unlike lanthanide ions, 1^st-order spin-orbit coupling (SOC) is cancelled by the ligand field for transition metal ions, and achieving high magnetic anisotropy is generally considered the Holy Grail for these ions. Results obtained with Fe(II) show that a contribution from first-order SOC coupling is not confined to low-coordination number complexes but can be implemented in a pentagonal bipyramid complexes (figure) by proper chemical design. This is confirmed by theoretical calculations and experimental magnetic behaviors consistent with the existence of large magnetic anisotropy, most salient feature being the SMM behaviors with large energy barriers for magnetization reversal. The observation of such a behavior without an applied static magnetic field is quite unique for a mononuclear 3d complex.

Influence of Capping Ligands on Metal-Nanoparticle-Driven Hydrogen Evolution and CO2 Reduction Reactions

Nuria Romero, Karine Philippot

ABSTRACT
This chapter looks into the influence of the functionalization of the surface of metal nanoparticles (MNPs) with ligands on their catalytic performance in two crucial reactions, the hydrogen evolution reaction (HER) and the CO2 reduction reaction (CO2RR). The birth of the surface functionalization of MNPs with ligands was greatly inspired by the advanced knowledge accumulated on molecular metal catalysts, whose physical and chemical properties can be tuned by coordinating appropriate ligands to the metal active center. This field of research has profited from the progress in the synthetic methods for the generation of MNPs and the evolution of the spectroscopic and analytical techniques for their exhaustive characterization, as well as the improvement of the computational techniques. Relevant examples will illustrate how the functionalization of the surface of MNPs allow to modulate the energy profile of catalytic intermediate species through electronic effects and regulate the product selectivity through hydrophobic/hydrophilic effects. Another key parameter is the tuning of the number of surface-active sites as a function of the metal to ligand ratio and the chemical nature of the coordinating ligand. Furthermore, in some peculiar cases, second coordination sphere effects have even been described in analogy to biological enzymes.

Contact:
Karine Philippot Karine.Philippot(at)lcc-toulouse.fr

Reference:
Influence of Capping Ligands on Metal-Nanoparticle-Driven Hydrogen Evolution and CO2 Reduction Reactions
Martí G., Lozano-Roche A., Romero N., Francàs L., Philippot K., Bofill R., García-Antón J., Sala X.
in Topics in Organometallic Chemistry. Surface Functionalized Metal Catalysts, L. M. Martínez-Prieto (Ed.), Springer International Publishing: Cham, 2024, vol. 75, pp. 105-132. (978-3-031-73841-8).
https://doi.org/10.1007/3418_2024_116
https://hal.science/hal-04821235

Lawsone

Molecule of the week ‘MOTW’ is a popular feature on the American Chemical Society’s website.

A publication concerning the reaction of lawsone with various aldehydes and isocyanides by teams R and V in collaboration with the University of Tartu (Estonia) is cited in “ACS molecule of the week”!

Read the article about Lawsone on ACS molecule of the week
Read the publication cited: Reaction of lawsone with various aldehydes and isocyanides

Contact: Michel Baltas  Michel.Baltas(at)lcc-toulouse.fr

Diverse Approaches for the Difunctionalization of PPH Dendrimers, Precise Versus Stochastic: How Does this Influence Catalytic Performance?

Massimo Petriccone, Régis Laurent, Anne-Marie Caminade,* and Rosa María Sebastián*
ACS Macro Lett. 2024, 13, 7, 853–858
Publication Date: June 25, 2024
https://doi.org/10.1021/acsmacrolett.4c00204

This work shows for the first time that when two functions are well organised on the surface of dendrimers, catalysis is systematically more efficient than if the two functions are randomly distributed.

Difunctionalisation of dendrimer surfaces is often used in biology. Until now, the compounds used have mostly been randomly distributed. It is in fact difficult to obtain precise difunctionalisation on most dendrimers. In this study, the scientists used polyphosphorhydrazone (PPH)-based dendrimers and demonstrated that with them a single precise difunctionalisation is possible. Catalysis research shows that precise functionalisation is systematically more effective than random functionalisation, introducing an entirely new concept in dendrimer science.

Research carried out in collaboration between a team from the LCC and a team from UAB Barcelona.

Contact:
Anne-Marie Caminade Anne-Marie.Caminade(at)lcc-toulouse.fr