Partners and International Organizations
(English)
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A, B, BG, CZ, DK, FIN, F, D, H, IRL, I, LV, NL, PL, P, RO, SI, E, S, CH, GB
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Abstract
(English)
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Electrochemical and Scanning Probe Investigations of Electrodes coated with Vitamin B12 Derivatives Based on the results of the previous year, additional ex-situ and in-situ STM experiments have been carried out with flame-annealed Au(111) electrodes coated with a symmetrical Vitamin B12 derivative bearing an alkane disulfide side chain. From the in-situ STM experiments it can be concluded that the B12 derivatives attached to the substrate via the disulfide chain form densely packed monolayers, where the lateral arrangement of the individual molecules appears to be controlled by the large corrinoid heads rather than by the ordered Au(111) surface structure. Combined voltammetric and STM experiments show that the dense B12 layer is removed to a large extent after polarisation of the modified electrode at potentials < -1250 mV vs. MSE, where a pronounced cathodic peak is observed in the voltammogram, which is associated with reductive desorption of the B12 coverage. However, a detailed analysis of the STM measurements indicates that the B12 coverage is not completely removed and that there remains a residual coverage. The nature and possible structural properties of this residual coverage has not been clarified yet, and further experiments in progress are expected to elucidate further the structural and coverage changes associated with the reductive desorption. Publications in preparation: - Synthesis of Disulfides and Preparation of Self Assembled Monolayers containing a Corrinoid Head Group: R. Luginbühl, J. Mendonca, H. Siegenthaler, R. Keese. - Electrochemical and STM Investigations of Electrodes coated with Vitamin B12 Derivatives: L. Durrer, R. Luginbühl, N. Simic, E. Szöcs, R. Keese, H. Siegenthaler.
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