Yves Fort

The results of a study on the evolution of HiPco single-walled carbon nanotubes during the oxidizing action of H₂SO₄ and HNO₃ are presented. The process conditions used have been chosen so as to avoid any significant damage to the nanotube structure. The type and level of functionalization, the location of the grafted functions on the surface of the nanotube and the changes in morphological characteristics of the samples were examined by using a wide and complementary range of analytical techniques. We propose an explanation for the differences in the oxidizing action of sulfuric and nitric acids. The combined results allow us to suggest possible reaction mechanisms that occur on the surface of the nanotube.

Over the past few decades, furopyridines have emerged as key structural subunits prevalent in a number of natural products and structural analogues associated with interesting biological activities. Consequently, considerable efforts have been devoted to the synthesis of these fused heterocyclic scaffolds. This review covers the main methodologies reported in the literature for the preparation of furopyridines.

With the aim to design fluorescent solids, a series of indeno[1′,2′:4,5]pyrido[2,1-a]isoindol-5-ones with various substituents was prepared. In these π-extended pentacyclic derivatives, the presence of a methyl group in the 7-position was found to have a critical influence on the fluorescence properties in the solid state. Crystal packing of the non-substituted derivatives shows strong π–π interactions causing quenching of the fluorescence. In contrast, by introducing a methyl substituent in the 7-position we obtained compounds with fluorescence quantum yield up to 32% in the solid state.

The effect of microwaves on the functionalization of single-walled carbon nanotubes (SWNTs) by the diazonium method was studied. The usage of a new approach led to the identification of the strength of the interaction (physical or chemical) between the functional groups and the carbon nanotube surface. Moreover, the nature (chemical formula) of the adsorbed/grafted functional groups was determined. According to thermogravimetric analysis coupled with mass spectrometry and Raman spectroscopy, the optimal functionalization level was reached after 5 min of reaction. Prolonged reaction times can lead to undesired reactions such as defunctionalization, solvent addition and polymerization of the grafted functions. The strength (chemi- vs physisorption) of the bonds between the grafted functional groups and the SWNTs is discussed showing the occurrence of physical adsorption as a consequence of defunctionalization after 15 min of reaction under microwaves. Several chemical mechanisms of grafting could be identified, and it was possible to distinguish conditions leading to the desired chemical grafting from those leading to undesired reactions such as physisorption and polymerization.

Magneto-responsivity can be imprinted in hard mesoporous silica materials using soft colloidal templates formed by magnetic surfactants. The materials exhibit a low to high spin transition due to geometrical constraints of the isolated iron ions grafted on the silica walls.