Compétences : Chimie de coordination / Synthèse / Cristallographie / Chiralité / Propriétés magnétiques
Porteuse du Projet ANR : MaChiNaCo AAPG 2019 PRC : Chiral magnetic nanocomposites for the induction of magnetochiral dichroism : In MaChiNaCo, we are designing and synthesizing magnetic nanocomposites, silica nanohelices grafted with magnetic molecules and nanoparticles, in order to observe magnetochiral dichroism (MChD). MChD is a spectroscopic phenomenon arising from the interplay between magnetism and chirality, and is a leading hypothesis for the origin of homochirality in life.
Only a few observations of this phenomenon can be found in the literature, due to the challenge of synthesizing robust systems that are simultaneously chiral and magnetic. We propose to overcome this difficulty by synthesizing novel nanocomposites, where the magnetism component will be supplied by the magnetic achiral chromophores, and the chirality component will be supplied by the nanohelices. We have shown that such helices can induce a chiral response (circular dichroism) in grafted non-chiral molecules…
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Education and scientific position
2010 : Habilitation à Diriger les Recherches (HDR) diploma from Université de Pierre et Marie Curie.
2020 – : CNRS researcher : Institut de Chimie de la Matière Condensée de Bordeaux (ICMCB), CNRS, France
2012–2020 : CNRS researcher : Centre de Recherche Paul Pascal (CRPP), CNRS, France
2006–2012 : CNRS researcher : Chimie ParisTech, Paris, France
2003–2006 : Postdoctoral fellow : Chimie ParisTech, Paris, France, Supervisor : G. Jaouen
1999 – 2003 : PhD student : Texas A&M University, College Station, TX, USA. Supervisor: F. A. Cotton
Coordination chemistry ; Synthesis ; Crystallography ; Chirality ; Magnetic properties
Crystal structure of Δ-[Mn(en)3](NO3)2 in the P6533 space group at 120 K.
My research interests are currently focused on the synthesis and structural characterization of chiral paramagnetic coordination complexes. The interplay of magnetism and chirality is manifested both in the influence of the electronic structure on the circular dichroism (CD), as well as by the differential absorption of light according to the direction of the magnetic field, known as magnetochiral dichroism (MChD). We are exploring these dichroisms in single crystals, solutions and in chiral nano-objects, in the Infrared, UV-vis, or X-ray energy ranges. The main goal is to understand how the chiral and electronic structure influences the intensity of the CD and MChiD signals. At the heart of this work is the enantiomeric resolution of the chiral objects, and this is being explored using chiral anions as well as selecting and engineering complexes that undergo spontaneous resolution in the solid state.
Chirality in single crystals: The left-handed or right-handed wrapping of bidentate ligands around transition metals in an octahedral geometry generates chiral compounds with the metal center as the stereogenic center (see figure for an example). Furthermore, the magnetic properties of such complexes can be easily controlled by the choice of the metal. In this work, we are taking advantage of the propensity of mononuclear tris(bi-dentate) systems to undergo spontaneous segregation of the enantiomers in the solid state to yield non-centrosymmetric crystals in the absence of any chiral auxillary. Measurements at the LNCMI in Grenoble have shown that some of these complexes display a strong MChD response.
Induced optical activity: Achiral molecules and nanoparticles can exhibit CD when in close proximity to chiral objects. In collaboration with the CBMN in Bordeaux, we are currently using helical nanoplatforms to induce CD in achiral magnetic complexes and nanoparticles. In this way, the magnetism and chirality can be controlled separately, thus allowing for a methodical study of induced MChD. This work is funded by the ANR MaChiNaCo. In another research line, we have found that Raman optical activity is induced in achiral solvents in which helicoidal polynuclear complexes have been dissolved; this is currently being investigated with the ISM in Bordeaux.
X-ray optical activity: X-ray natural circular dichroism (XNCD) is element-selective, but can only be observed in ordered media that belong to one of 13 point groups. Even though it is still in its infancy, this spectroscopy is a very sensitive probe of the chiral molecular environment around the absorbing atom. We have been working with the ESRF in Grenoble and the IMPMC in Paris, to observe XNCD in chiral coordination systems, and to correlate the dichroism spectra to the electronic structure of the absorbing atom. We have also used XNCD to map the chirality of individual crystals in an assembly. Because birefringence effects disappear when using X-rays, this technique is a rapid way to examine solid state chiral genesis and deracemization processes.
E. Pouget (CBMN, Bordeaux)
G. Rikken and C. Train (LNCMI, Grenoble)
B. Pichon (IPCMS, Strasbourg)
P. Rosa (ICMCB)
T. Buffeteau and N. Daugey (ISM, Bordeaux)
Ph. Sainctavit (IMPMC, Paris)
A. Rogalev and F. Wilhelm (ESRF, Grenoble)
Scientific production and supervision
76 articles / 1 patent
Supervision : 4 PhD students (currently 1), 2 postdoctoral fellow, 3 master students, 16 undergraduate students.
10 Relevant publications (total 20)
M. Cortijo, A. Valentin-Perez, A. Rogalev, F. Wilhelm, Ph. Sainctavit, P. Rosa, E. A. Hillard, Rapid Discrimination of Crystal Handedness by X-ray Natural Circular Dichroism (XNCD) Mapping, Chem. Eur. J., 2020; 10.1002/chem.202001783.
M. Cortijo, A. Valentin-Perez, M. Rouzières, R. Clérac, P. Rosa, E. A. Hillard, Tris(ethylenediamine) cobalt(II) and manganese(II) nitrates, Crystals, 2020, 10(6), 472, 10.3390/cryst10060472.
M. Cortijo, A. Valentin-Perez, P. Rosa, N. Daugey, T. Buffeteau, E. A. Hillard, Resolution, structures, and vibrational circular dichroism of helicoidal trinickel and tricobalt paddlewheel complexes, Chirality, 2020, 32(6), 753, 10.1002/chir.23211.
A. Cornia, A.-L. Barra, V. Bulicanu, R. Clérac, M. Cortijo, E. A. Hillard, R. Galavotti, A. Lunghi, A; Nicolini, M. Rouzières, L. Sorace, F. Totti, The Origin of Magnetic Anisotropy and Single-Molecule Magnet Behavior in Chromium(II)-Based Extended Metal Atom Chains, Inorg. Chem., 2020, 59(3), 1763, 10.1021/acs.inorgchem.9b02994.
A. Srinivasan, X. Wang, R. Clérac, M. Rouzières, L. R. Falvello, J. E. McGrady, E. A. Hillard, Temperature dependence of the spin state and geometry in tricobalt paddlewheel complexes with halide axial ligands, Dalton Trans., 2018, 47(46), 16798, 10.1039/c8dt03833c.
A. Valentin-Perez, A. Naim, E. A. Hillard, P. Rosa, M. Cortijo, M, Enantiopure Chiral Coordination Polymers Based on Polynuclear Paddlewheel Helices and Arsenyl Tartrate, Polymers, 2018, 10(3), 311; 10.3390/polym10030311.
A. Srinivasan, M. Cortijo, V. Bulicanu, A. Naim, R. Clérac, Ph. Sainctavit, A. Rogalev, F. Wilhelm, P. Rosa, E. A. Hillard, Enantiomeric resolution and X-ray optical activity of a tricobalt extended metal atom chain, Chem. Sci., 2018, 9(5), 1136, 10.1039/c7sc04131d.
M. Cortijo, V. Bulicanu, K. S. Pedersen, M. Rouzieres, J. Bendix, R. Clérac, E. A. Hillard, Rational Self-Assembly of Tricobalt Extended Metal Atom Chains and [MF6]2- Building Blocks into One-Dimensional Coordination Polymers, Eur. J. Inorg. Chem., 2018, 3-4, 320, 10.1002/ejic.201701084.
V. Bulicanu, K. S. Pedersen, M. Rouzieres, J. Bendix, P. Dechambenoit, R. Clerac, E. A. Hillard, One-dimensional coordination polymers of [Co3(dpa)4]2+ and [MF6]2- (M = ReIV, ZrIV and SnIV), Chem. Commun., 2015, 51(100), 17748, 10.1039/c5cc06704a.
E. A.Hillard, A. Vessieres, L Thouin, G. Jaouen, C. Amatore, Ferrocene-mediated proton-coupled electron transfer in a series of ferrocifen-type breast-cancer drug candidates, Angew. Chem. Int. Ed., 2006, 45(2), 285, 10.1002/anie.200502925ISTEX.