René Clément

Electropolymerization of methoxyaniline: experimental results and frontier orbital interpretation

Abstract This report describes the electropolymerization reactions of ortho - and meta -methoxyanilines on a gold electrode and on a gold/polyaniline electrode. It is shown that the outcome of the electrooxidation process is sensitive to the methoxy group position but not to the nature of the electrode which, nevertheless, exerts a catalytic effect. These effects are discussed in terms of frontier orbital interactions. This approach suggests that film growth involves the coupling of a nonoxidized monomeric unit via one of its carbon atoms onto a deprotonated NH 2 group of the oxidized polymeric chain.

The NiPS3-Cobaltocene intercalation compound : a new ferromagnet

Abstract The layered NiPS3-Cobaltocene intercalation compound is shown to acquire spontaneous magnetization below 70 K, although NiPS3 orders antiferromagnetically. An XPS study of this intercalate is described, which shows that the electronic density at the Ni, P and S atoms is increased upon intercalation.

Synthesis and luminescence properties of CdPS3 intercalated with rare earth cations

Abstract Nd 3+ , Sm 3+ and Eu 3+ have been intercalated by a cation exchange procedure into the layered lattice of CdPS 3 . X-ray diffraction measurements of the interlamellar expansion demonstrate that the cations initially occupy the interlamellar planes and are solvated by a water bilayer. Dehydration of the lattice occurs at 120°C and is accompanied by a substantial decrease in the interlamellar spacing. Analysis of the host lattice photoluminescence and i.r. spectra indicate cadmium cation vacancies are created in the host lattice to balance the intercalated charge. The crystal field effects on the rare earth cation photoluminescence indicate that the cations have entered the intralamellar cation vacancies to form a complex defect center with C 2 or lower symmetry. It is proposed that replacing dipositive Cd 2+ cations with RE 3+ cations creates a characteristic complex involving two RE 3+ cations and a lattice vacancy, V 2- .

Molecular Composites of the MPS3 Layered Inorganic Polymers: Chemistry, Magnetic and Dielectric Properties

Developments in the field of intercalation chemistry of the layered MPS3 (M= Mn, Fe) host lattices lead to materials with unusual magnetic properties. Various organic and organometallic intercalates have been synthesized, where the electrical charge of the guest cations is counterbalanced by the removal of an equivalent amount of intralayer M2+ cations. In contrast to the pristine MPS3 materials which behave as typical antiferromagnets, the composite materials exhibit spontaneous macroscopic magnetization below a Curie temperature Tc. Both Tc and intensity of the magnetization depend on the guest species. The Curie temperature of the FePS3-pyridinium composite exceeds 90 K. This new material is the first insulating ’molecular’ material to have a Curie temperature above that of liquid nitrogen. Preliminary results of a study of the dielectric properties of pyridinium intercalates indicate the occurence of order-disorder transitions.

Catalytic Sulfide Ion Oxidation over substituted NiPS3 layered compounds and their sodium intercalates: A kinetic and XPS study

The bimetallic Ni 0.6 Fe 0.4 PS 3 and and Ni 0.83 Cu 0.34 PS 3 layered compounds are shown to be more efficient than NiPS 3 at catalysing the oxydation of sulfide ions into sulfur at room temperature. The related sodium intercalates exhibit an even larger efficiency. An XPS study of these compounds is presented and discussed in relation to the catalytic activity.