Optical and Magnetic Molecular Switches Based on Metal-to

GECOM-CONCOORD 2016
Optical and Magnetic Molecular Switches Based on Metal-to-Metal
Electron Transfer Mechanism: from Solid State to Solution
Evangelia S. Koumousi,a,b,c,d Ie-Rang Jeon,a,b,c,d Dmitri Mitcov,a,b Diana Siretanu,a,b
Pierre Dechambenoit,a,b Corine Mathonière,c,d and Rodolphe Clérac*,a,b
a
CNRS, CRPP, UPR 8641, Pessac, F-33600, France ; b Univ. Bordeaux, CRPP, UPR 8641, Pessac, F-33600,
France ; c CNRS, UPR 9048, ICMCB, Pessac, F-33600, France ; d Univ. Bordeaux, ICMCB, UPR 9048, Pessac,
F-33600, France
Email: [email protected]
The design of molecule-based systems displaying tunable optical and/or magnetic properties under
external stimuli received a great deal of attention in the past few years. This interest is driven by the
potential applications in high-performance molecule-based electronics. As an example, 3D Fe/Co
Prussian blue compounds exhibit a concomitant change in magnetic and optical properties due to a
temperature- or light-induced metal-to-metal electron transfer (ET). The foregoing remarkable
properties in Prussian blues prompted us to design soluble molecular fragments of these coordination
networks through a rational building-block approach in order to mimic their properties on a single
molecule (See Figure).[1-4] With a judicious choice of the ligands for metal ion precursors, we prepared
a octanuclear,[1] tetranuclear[2] and recently dinuclear[3] cyanido-bridged Fe/Co complexes. In the solid
state, while an intramolecular ET is observed for the [Co4Fe4] and [Co2Fe2] complexes,[1,2] the Co ion
of our first dinuclear complex exhibits a spin crossover (SCO) involving a [Fe IIILS-CN-CoIILS] ground
state and a thermally populated [FeIIILS-CN-CoIIHS] state.[3] To our knowledge, this compound is the
only example of a heterobimetallic complex exhibiting a CoII SCO. Remarkably, our studies of these
[ConFen] complexes in solution
reveal important optical and
magnetic changes induced by an
intramolecular metal-to-metal
ET triggered and modulated by
a controlled protonation of the
complex, by the solvent nature
or by temperature. Therefore,
these molecules act as different
molecular switches depending
on their physical state and
external stimuli.[3] These results motivated us to design new dinuclear [FeCo] complexes exhibiting
both thermally and light induced electron transfer in solid state. Learning from these previous systems,
new dinuclear complexes[4] have been designed by a rational building-block approach. Combined
structural, spectroscopic, magnetic and photomagnetic studies reveal that a metal-to-metal electron
transfer that can be triggered by light, temperature and lattice contents is observed for the first time in
solid state for a dinuclear cyanido-bridged Fe/Co complex.[4]
Acknowledgements. We thank the Centre National de la Recherche Scientifique (CNRS), the Conseil
Regional d’Aquitaine, the University of Bordeaux and the ANR for financial support.
[1]. D. Li et al., J. Am. Chem. Soc. 130, 252-258 (2008).
[2]. Y. Zhang et al., Angew. Chem. Int. Ed. 49, 3752-3756 (2010) ; D. Siretanu, et al., Chem. Eur. J. 17, 1170411708 (2011) ; Y. Zhang et al., J. Am. Chem. Soc. 136, 16854-16864 (2014).
[3]. I.-R. Jeon, et al., Chem. Sci. 4, 2463-2470 (2013).
[4]. E. S. Koumousi et al., J. Am. Chem. Soc. 136, 15461-15464 (2014).