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Home > Members > Permanents > Stéphane Rigaut

Prof. Stéphane Rigaut

Institut des Sciences Chimiques de Rennes
UMR 6226 CNRS - Université Rennes 1
Campus de Beaulieu - Build. 10C - Room 929
35042 Rennes Cedex - France

Phone : 33 (0) 2 23 23 57 67
Fax : 33 (0) 2 23 23 69 39

Email: stephane.rigaut@univ-rennes1.fr

Education and professionnal experience

Stéphane Rigaut obtained his Ph.D in 1997 from the Université Bordeaux 1 under the supervision of Prof. Didier Astruc and Dr. Marie-Hélène Delville in “Redox Catalysis with mono and polymetallic electron reservoir metal complexes”.

After a post-doctoral position in Minneapolis (USA) with Prof. Larry L. Miller dealing with “Vapoconductivity in Dendrimers and swollen commodity polymers”, he was hired in 1998 as an assistant Professor in Prof. Daniel Touchard’s group (Université de Rennes 1). The topic of his research was the study of electron transfer processes in redox active ruthenium carbon-rich polymetallic complexes with unusual topologies.

In 2008, he obtained a full Professor position and his interest moved toward the building of organometallic molecular wires and switches for molecular electronics.

Research interests

Carbon-Rich Systems and Molecular Electronics (Prof. Stéphane Rigaut / Dr. Lucie Norel)

The aim of our current project is to develop novel fundamental issues for (i) conducting and (ii) switching molecular materials displaying magnetic and luminescent properties with the help of redox active ruthenium complexes and/or photochromic units toward multifunctional systems:


1/ Ruthenium systems

We demonstrated that ruthenium organometallic compounds are particularly suitable for promoting exceptionally efficient intramolecular electronic delocalization over long length scale up to at least 28 Å (J. Am. Chem. Soc. 2010, 130, 5638; Inorg. Chem. 2012, 51, 1902; Organometallics 2014, 33, 4672). Consequently, electrical transport characteristics of such systems shows weak length dependence via direct tunneling or thermally activated hopping (J. Phys. Chem. C 2011, 115, 19955).

Our interest is now related to the building of switching devices based on these redox active ruthenium carbon-rich organometallics associated with specific units with special properties:

Luminescence redox switch. the association between an ytterbium ion and a ruthenium carbon-rich complex enables the first switching of the near-IR Yb(III) luminescence by taking advantage of the redox commutation of the carbon-rich antenna.
(J. Am. Chem. Soc. 2011, 133, 6174; Organometallics 2014, 33, 4824)

Single Molecule Magnet (SMM) switching. Further association with an anisotropic dysprosium ion leads also to a unique complex showing SMM behaviour and enhancement of the magnetic slow relaxation upon oxidation.
(Chem. Commun. 2012, 48, 3948; Inorg. Chem. 2014, 53, 2361)

Surface Grafting. Ruthenium complexes exhibit fast electron transfer kinetics (≈ 104 s-1) combined to low oxidation potentials and discrete oxidation events (up to 4 distinct states) in Self-Assembled Monolayers making them suitable for immobilized redox switches and charge storage devices for molecular optoelectronics (Langmuir 2015, 31, 7138; Chem. Electro. Chem. 2015, 2, 1799).

2/ Photochromic systems:

Luminescence photochromic switch. Dithienylethene (DTE) modified dipicolinic amide ligand can be a versatile tool to modulate luminescence: with Eu(III), the DTE ligand quenches the red luminescence upon ring closure, whereas with Yb(III), ring closure can be used to turn on the luminescence in the NIR range (Inorg. Chem. 2016, 55, 12635).

Magnetism with the help of a photochromic system. A spiropyran-based switchable ligand isomerizes upon reaction with lanthanide(III) precursors to generate complexes with unusual N3O5 coordination sphere. The air stable Dy(III) complex shows a hysteresis loop at 2 K and a very strong axial magnetic anisotropy generated by the merocyanine phenolate donor (Chem. Eur. J. 2016, 22, 15222).

3/ Combined multifunctional systems

Multi-control of a photochromic unit. Perturbation of a DTE system with a ruthenium system provides unique light- and electro-triggered multifunctional switches featuring electrocyclization at remarkably low voltage. It is thus addressable with a combination of electrochemical and optical stimuli.
(Org. Lett. 2012, 14, 4454; Inorg. Chem. 2014, 53, 8173)

Multi-functional surfaces. We obtained surfaces combining switching triggered by electrochemical oxidation at low potential and by light at distinct wavelengths for write-and-erase functions, along with an access to different oxidation states. A non-destructive electrochemical read-out is achieved at high scan rate that prevents electrochemical closing giving appealing properties for application in molecular electronics (Chem. Eur. J. 2017 DOI: 10.1002/chem.201701903).

Optical and redox control of conductivity. Such systems allowed the achievement of the first photo- and electromodulable molecular transport junctions in nanogaps. The addressable and stepwise control of molecular isomerization can be repeatedly and reversibly completed with a judicious use of the orthogonal optical and electrochemical stimuli to reach the controllable switching of conductivity between two distinct states.
(Chem. Sci. 2012, 3, 3113; Nat. Commun. 2014, 5: 3023)

Collaborations

  • Prof. Dan Frisbie (University of Minnesota, USA): Current-voltage characteristics using CP-AFMRetour ligne automatique
  • Prof. Xiaodong Chen (Nanyang Technological University, Singapore): Current-voltage characteristics in nanogapsRetour ligne automatique
  • Dr. Jerôme Cornil (University of Mons, Belgium), Dr. Karine Costuas (University of Rennes): Theoretical calculationsRetour ligne automatique
  • Prof. Rainer Winter (University of Konstanz, Germany): Ruthenium vinyl complexesRetour ligne automatique
  • Dr. Sylvie Choua, Prof. Philippe Turek (Strasbourg, France): EPR spectroscopyRetour ligne automatique
  • Dr. Corinne Lagrost (University of Rennes): Surface modifications / High speed electrochemistryRetour ligne automatique
  • Dr. Olivier Maury (ENS Lyon), Prof. Elena Ishow (University of Nantes): Luminescent compounds
  • Dr. Kevin Bernot (INSA Rennes), Dr. Roberta Sessoli (University of Firenze): Magnetic measurements
  • Dr. Remi Métivier (ENS Cachan): study of photochromic reactions

Publications referenced in HAL since 2006