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Publications: Articles

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Guyot, E., Seghir, S., Lecuire, J.M., Boulanger, C., Levi, M.D., Shilina, Y., Dargel, V. and Aurbach, D.
Journal of Electrochemical Society, 160(3):A420-A425

Equipe: Département CP2S : Chimie et électrochimie des matériaux

Grison, Claire, Escande, Vincent, Petit, Eddy, Garoux, Laetitia, Boulanger, Clotilde and Grison, Claude
RSC Advances, 3(44):22340-22345

Resume: Psychotria douarrei and Geissois pruinosa are known as a hypernickelophore plants. The study of their chemical characteristics was revisited to demonstrate a novel potential of this natural resource for Green Chemistry. P. douarrei showed a unique composition, which led to a novel concept of plant-based catalytic chemistry. The supported Biginelli reaction illustrated an interest of this concept for green organic synthesis.

Equipe: Département CP2S : Chimie et électrochimie des matériaux

Ahlers, Michael, Stein, Nicolas, Broch, Laurent and Brand, Izabella
Journal of Electroanalytical Chemistry, 706(0):140-148

Mots clefs: Collagen molecule Self-assembly Au electrode In situ ellipsometry Capacitance Polarization modulation infrared reflection–absorption spectroscopy (PM IRRAS)

Resume: Abstract The influence of the potential applied to the polycrystalline gold electrode on the adsorption state and structure of collagen molecules were studied by means of electrochemistry, in situ ellipsometry and in situ polarization modulation infrared reflection–absorption spectroscopy. At the macroscopic level, potential and the corresponding charge accumulated on the gold electrode determine the adsorption process of the collagen film on the Au electrode surface. The protein film is stable on the electrode surface at potentials close to the potential of zero charge. The protein film sustains a large negative potential drop (??M|S ? ?0.5 V) whereas it is unstable at a small positive potential drop (??M|S ? 0.1 V) across the film. Positive net charge accumulated on the Au surface causes electrostatic repulsions of collagen molecules bearing a positive net charge. Loosening of water and destabilization of the protein film reflect repulsions between the Au electrode and the collagen molecules. In contrast, at charge densities between ?8 < ?M < ?20 ?C cm?2 electrostatic attractions between the electrode surface and the protein molecule appear. A stable, well hydrated collagen film is formed on the Au surface. Higher negative charges accumulated on the electrode surface lead to swelling on the protein film by water and lead to the desorption of the protein film from the Au surface. In situ spectroelectrochemical studies show that at the molecular level neither the secondary structure nor the orientation of collagen molecules are affected by electrical potentials. Independently of the applied potential and electric fields acting on the film the collagen molecule maintains its native structure. Collagen molecules adsorbed on the Au surface form a heterogeneous film with well-defined structure and unusual stability at the molecular level.

Equipe: Département CP2S : Chimie et électrochimie des matériaux

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