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International audience; The present work describes the synthesis and characterization of hybrid materials based on β-cyclodextrin (β-CD) and cetyltrimethylammonium bromide (CTAB) intercalated into saponite (SAP) and a commercially available powder of anthocyanin dye, Crystal Red Grape (RG). The interactions between the organic dye guest and the organo-clay host were investigated by X-ray diffraction, thermogravimetric analysis, transmission electronic microscopy and 13C solid state nuclear magnetic resonance. The results support complex formation between β-CD and CTAB, their intercalation into the clay interlayer spaces or surface loading, and their interaction with RG (CTAB_SAP-RG, β-CD_SAP-RG and β-CD + CTAB_SAP-RG). The hybrid pigments formed exhibit different colors, enhanced stability against visible light irradiation and basic pH conditions. These hybrid pigments are environmentally friendly and can be promising candidates in different application fields.

International audience; Hybrid pigments based on organo-saponite (cetyltrimethyl ammonium bromide (CTAB-Sap) and a commercial anthocyanin (ACN) dye, Crystal Red Grape, were prepared. The interactions between organic dye guest and hosts (including saponite and organo-saponite) were investigated by X-ray diffraction, transmission electron microscopy and Fourier transform infrared spectroscopy. The pigments exhibit different colors function of their host-guest interactions. The blue color of organo-clay-anthocyanin indicates the stabilization of quinoidal base form of the dye. The hybrids have good stability against visible light irradiation and basic pH conditions. These dyed materials are environmentally friendly and can be promising candidates in different application fields.

International audience; The polycondensation of amino acids to oligopeptides is an important step in the origins of life, and known to be effective on several mineral surfaces. The data available on clay mineral surfaces are heterogeneous and sometimes contradictory, however. The objective of the present work is to investigate the adsorption of a selected amino acid, alanine, in expanding and non-expanding clays and then study the possible peptide condensation by thermal activation. A multi-technique approach was used, including macroscopic measurements of the adsorption process (adsorption isotherms and pH-metry), and in situ molecular-level characterization of the solids obtained (X-ray diffraction, thermogravimetric analysis and infrared spectroscopy). The results indicate that only weak interaction is established between alanine molecule and kaolinite surfaces, most of the deposited molecules being only physically retained. Thermal activation of alanine/kaolinite only led to desorption. In contrast, higher-energy adsorption mechanisms were at play in hectorite, including cation exchange and coordinative adsorption to the interlayer ions, and alanine species adsorbed in this way were observed to form cyclic dimers upon activation between 160 and 270 °C.

International audience; In this work, hectorite/alizarin pigments were prepared at pH 9 and 12. Hectorite was initially modified with cetyltrimethylammonium and pectine to produce organo-hectorites. The influence of organo-hectorite on the stabilization of alizarin was evaluated. X-ray diffraction suggested the formation of exfoliated/delaminated structures after organofunctionalization of the hectorite. For raw hectorite and their derivatives with pectin, the formation of hybrid pigments was confirmed by infrared spectroscopy. Thermogravimetry curves confirm the hectorite organofunctionalization and that the alizarin loading was higher at pH 12. The hybrids prepared at pH 12 show more photostability than ones prepared at pH 9. This behavior was probably due to the total deprotonation of dye molecules, which promoted better interactions between the hosts and the guests.