Molecular Materials

Molecular Switch

Spectroscopies

para-NMR & XAS-XMCD

 

News

 Atypical structures that are not commonly observed in oxamate coordination chemistry are obtained in this work: (1) shows a macrocyclic  mixed‐valence cobalt complexes that shows field-induced SMM behaviour,  while (2) forms a helical chiral chain featuring antiferromagnetic interactions.

More in Eur. J. Inorg. Chem. 2020 DOI : 10.1002/ejic.202000490

_______________________________________________________________________________________________________________

What a S'witch !

Cs⊂{Fe4Fe4} cube can be reversibly converted into 9 different redox states in solution. By changing the electric potential, LMCT, MLCT and MMCT transitions can be switched on and off  leading to at least 3 very different optical signatures. 
Not only that ! The cube is also a MMS,  showing a Spin-transition in the neutral form in the solide-state.

More in Chem. Commun. 2020
______________________________________________________________________________________________________________

The investigated Fe2Co2 square complex shows a Fe(III/II)-Co(II/III) Electron Transfer equilibrium in MeOH solution, with Teq near 0°C.  Crystallization at 35°C allows isolating the square in its paramagnetic FeIII-CoII electronic state (see Part I, RSC Adv. 2016 S. De et al.).

Here we showed  that application of pressure allows recovering a Fe(III)Co(II) <=> Fe(II)-Co(III) Electron Transfer Transition in the solid-state.

Remarkably, the FeCo shows an unusual p-enhanced hysteresis that allows reaching bistability at room temperature.

More in Angew. Chem. 2020 DOI : 10.1002/anie.202008051

_______________________________________________________________________________________________________________

Many efforts are currently devoted in depositing ultra-thin layers of SCO Molecular Switches onto surfaces. Most of the time,  researchers use evaporation methods applied to robust neutral monometallic complexes. Things are more complicated with polymetallic charged complexes that can undergo dissociation, etc... unless you find the good way.

Here we showed with the help of the colleagues from LRS lab (Sorbonne Univ.) that EI allow depositing cubes onto Gold(111)

What's Next ?  Probing that the switching properties are preserved, another story...

More in Chem. Commun. 2020 DOI :10.1039/D0CC01906B

______________________________________________________________________________________________________________

While the switchable properties of the FeCo PBA (first observed by Sato et al in 1996) can be "easily" transferred to discrete molecular systems, things seem much more complicated in the case of the FeMn systems... After some efforts studying cyanide-bridged FeMn systems showing intringuing behaviours, we decided to publish that cube, which shows a  fragile transition ascribed to a FeMn electron transfer, together with interesting electronic properties in solution...
More in Angew. Chem. 2020, DOI: 10.1002/anie.201916199

______________________________________________________________________________________________________________

In the frame of an ANR-JST joined project, we have been investigated the intercalation of cation into cyanido-molecular materials.

In this work Juan and Akira showed that "simple" monodimentional cyanide-bridged complex can reversibly intercalate Li+ ions. Although the material becomes amorphous during the Li intercalation process, crystallinity is recovered once the Li is removed. All the process can be repeated at least 20 times without significant loss of capacity.

More in Chem. Comm. 2018 DOI : 10.1039/C8CC01374H

______________________________________________________________________________________________________________

Superparamagnetic nanoparticles are promising objects for data storage or medical applications. In the smallest systems, the properties are governed by the magnetic anisotropy. Here we report a molecule-based synthetic strategy to enhance this anisotropy in sub-10-nm nanoparticles. It consists of the fabrication of composite materials where anisotropic molecular complexes are coordinated to the surface of the nanoparticles. Magnetic measurements indicate the significant enhancement of the anisotropy in the final objects. Indeed, the functionalized nanoparticles show a threefold increase of the blocking temperature and a coercive field increased by one order of magnitude.

More in Nat. Comm. 2015 DOI : 10.1038/ncomms10139

______________________________________________________________________________________________________________

CONTACT

Sorbonne Université, Faculté des Sciences et Ingénierie
4 Place Jussieu 75005 PARIS
Building 33-43 5th floor

rodrigue lescouëzec:  00 33 (0)1 44 27 30 75

©2020  ERMMES