Dendrimers are hyperbranched polymers whose structure resembles that of trees. Their stepwise and repeated synthesis ensures a perfectly defined structure and shape. Starting from a multifunctional central core, each cycle of synthesis induces an increase of the number of functional groups and of the size of the dendrimer, creating a new "generation". When the number of generation increases, the shape of the dendrimers becomes globular in most cases, and the end groups are generally located on the surface, hence they are easily accessible and reactive. The properties of dendrimers are mainly driven by the type of end groups they bear. The project concerns the synthesis of several generations of dendrimers having two types of functional groups: one for ensuring the solubility in water and another one bringing catalytic properties. Both types of functional groups can be located either in two different parts of the structure (for instance at the core and on the surface), or in two distinct parts of the surface, or close together and every where in the surface. The catalytic groups will be designed in collaboration with our partners. The catalytic properties of various generations (sizes) of dendrimers will be tested and studied in part in Toulouse and in part in the institutions of our partners, and compared with the catalytic properties of (small) model compounds
A preliminary knowledge in laboratory techniques used in synthesis will be welcome.
Leading references: Galliot C., Larré C., Caminade A.M., Majoral J.P. Science 1997, 277, 1981. Majoral J.P., Caminade A.M. Chem.Rev. 1999, 99, 845. Maraval V., Caminade A.M., Majoral J.P., Blais J.C. Angew. Chem. Int. Ed. 2003, 42, 1822.
Contact: Anne-Marie Caminade or Jean-Pierre Majoral, Laboratoire de Chimie de Coordination du CNRS, 205 route de Narbonne, 31077 Toulouse Cedex 4, FRANCE
The project will lead to the acquisition of a Doctoral degree from the Université Paul Sabatier, Toulouse. Financing of this thesis is available from this European RTN programme for 24 months. Additional months (if necessary) will be spent in another Laboratory within the Network, or outside of the Network, or in Toulouse, depending on available funding.
High oxidation organometallic compounds, mostly supported by oxo ligands, are now a well established family and exhibit remarkable catalytic activities especially in oxidation processes. To date, stoichiometric and catalytic organometallic chemistry has been extended to aqueous conditions only for low and middle-valent systems, with the use of hydrophilic substituents on ligands such as phosphines, cyclopentadienyl, etc. The fundamental exploration of high oxidation state organometallic compounds in water promises to open up new and efficient avenues to catalytic and electrocatalytic applications in the greenest available solvent. Recent work has focused on the speciation and on the electrochemical and chemical reduction of the Cp*MoVI system. The proposed research activity for this Ph.D. thesis is the development of the aqueous chemistry for other high oxidation state systems, including WVI, ReVII and OsVIII. The student will learn the basic techniques of organometallic synthesis including manipulations under an inert atmosphere, various spectroscopic and spectrometric characterization techniques (IR, UV-visible, NMR, EPR, mass spectrometry, ?) structural analyses by X-ray diffraction, analytical techniques (voltammetry, pH-metry, conductimetry, ?), and rapid-mixing kinetic determinations (stopped-flow).
Poli, R., Chem. Eur. J. "High Oxidation State Organometallic Chemistry in Aqueous Media: New Opportunities for Catalysis and Electrocatalysis", 2004, in press (Concept article).
Contact: Rinaldo Poli, Laboratoire de Chimie de Coordination du CNRS, 205 route de Narbonne, 31077 Toulouse Cedex 4, France. E-mail: firstname.lastname@example.org