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
e-mail: caminade@lcc-toulouse.fr
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).
Leading reference:
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:
poli@lcc-toulouse.fr