Hervé Chollet

NEW SILICA-GEL-BOUND POLYAZACYCLOALKANES AND CHARACTERIZATION OF THEIR COPPER(II) COMPLEXES USING ELECTRON SPIN RESONANCE SPECTROSCOPY

Several tetraazamacrocycle-bonded silica gels have been synthesized and characterized. 1,4,7,10-Tetraazacyclododecane, 1,4,8,11-tetraazacyclotetradecane and 1,5,9,13-tetraazacyclohexadecane have been covalently bound to silica gel and their respective copper(II) complexes characterized. Three different methods were used for capacity determinations: quantitative ESR measurements of copper(II) complexes, nitrogen, carbon and copper elemental analysis and UV/VIS measurements.

Selective Lanthanides Sequestration Based on a Self‐Assembled Organosilica

In this paper, we investigate the cation-exchange properties of a self-assembled hybrid material towards trivalent ions, lanthanides (La(3+), Eu(3+), Gd(3+), Yb(3+)) and Fe(3+). The bis-zwitterionic lamellar material was prepared by sol-gel process from only 3-aminopropyltriethoxysilane (APTES), succinic anhydride, and ethylenediamine. In ethanol heated under reflux, the exchange ethylenediammonium versus Ln(3+) proved to be complete by complexometry measurements and elemental analyses, one Cl(-) ion per one Ln(III) remaining as expected for charge balance. In aqueous solution at 20 degrees C, the material was found to be selective towards lanthanide in spite of the similarity of their ionic radii. The cation uptake depends on the nature of the salt, the difference between two lanthanides reaching up to 20 % in some cases. Finally, ion-exchange reaction with FeCl(3) was chosen as a probe to get more information on the material after incorporation of trivalent ions. Based on Mössbauer spectroscopic investigations on the resulting material in conjunction with the XRD analysis of materials containing trivalent ions, a structural model was proposed to describe the incorporation of trivalent ions by exchange reaction within the original zwitterionic material.

Synthesis and cation-exchange properties of a bis-zwitterionic lamellar hybrid material

The synthesis of a bis-zwitterionic lamellar hybrid material containing ammonium carboxylate groups is described. Cation-exchange properties of this material towards transition metal and lanthanide ions were studied as well as the regeneration and reuse of the material.

A New Versatile Synthesis of N,N′,N″,N″′-Tetra-(2-carboxyethyl)-and N,N′,N″,N″′-Tetra-(3-aminopropyl)-tetraazacycloalkanes by Michael Addition of Polyazacycloalkanes to Acrylic Acid and Acrylonitrile

Abstract A smooth and convenient one step synthesis of N,N′,N″,N″′-tetra-(2-carboxyethyl)-tetraazacycloalkanes is reported. These compounds are synthesized by Michael addition of tetraazacycloalkanes to acrylic acid. The same Michael addition of tetraazacycloalkanes to an excess of acrylonitrile also leads to the corresponding tetracyanoethylated derivatives. The reduction of such tetracyanoethylated compounds is a new way of preparation for the corresponding primary amines.