Research objectives and content RESEARCH PROPOSAL
This research concerns the design and synthesis of new
molecular compounds with coexistence of localized spins and itinerant electrons in strong interaction. In particular, associations of organic and inorganic blocks inside radical cation salts prepared from TTF and TCNQ derivatives have already given low temperatures magnetic insulators. It has been argued that in these low dimensional solids direct exchange interactions can occur and give rise to antiferromagnetic coupling at low temperature However, it appears that this strategy is limited and it would be more efficient to link directly by chemical bonds the donor organic part and the associated transition metals inside an hybrid molecule as in molecular magnets. Besides associated with intramolecular magnetic interactions, intermolecular indirect exchange could be introduced through the so called 'RKKY mechanism' which should be peculiar in these materials. The first step of this work will be therefore to synthesize robust metal complexes of ligands containing TTF (and TCNQ moieties), the second step will be to study the redox potentials of both the ligand and the metal with the possible occurence of intervalence transitions and then to prepare by electrocristallization new radical cation salts. After structural determinations we will study the magnetic and electric properties of these new materials. The creation of these new hybrid materials will favour the interplay of metallic conductivity and localized magnetism, and maybe lead to the formation of a molecular conducting ferromagnet. A further step would be in the future to examine the competition between a low temperature magnetic ordering and a superconducting state.
Training content (objective, benefit and expected impact)
The objective is to learn about magnetic properties (ESR spectrometer, magnetization measurements) and to establish the relationship between the design and the synthesis of molecular blocks and the physical properties of the resulting compounds. The benefit and the impact will be to have a better rationalized approach in this research on novel materials. Links with industry / industrial relevance (22)