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O: Fachverband Oberflächenphysik

O 106: Poster Session VIII: Poster to Mini-Symposium: Electrified solid-liquid interfaces III

O 106.5: Poster

Donnerstag, 4. März 2021, 13:30–15:30, P

Amino acids adsorption at electrified gold/aqueous interface — •Denys Biriukov^1,2 and Zdenek Futera² — ¹Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 16610 Prague 6, Czech Republic — ²Institute of Physics, Faculty of Science, University of South Bohemia, Branišovská 1760, 370 05 České Budějovice 2, Czech Republic

Molecular detailization of gold/aqueous interfaces in an external electric field stimulates various applications in electrochemistry. In this contribution, we investigate the adsorption of several, particularly charged amino acids, since they represent principal components of proteins and other molecular junctions. Using all-atom molecular dynamics simulations and free energy calculations, we show that positively charged amino acids exhibit larger interfacial changes than negatively charged when an external electric field is applied. The reason is the ability of the side-chain of positively charged amines to replace water molecules in the first adsorption layer at Au (111) surface. Charge-neutral amino acids are also capable to penetrate into the interfacial water structure, so their response to an applied electric field reflects that of positively charged amino acids. However, it is overall less significant due to charge-neutrality of the molecule. Contrary, negatively charged carboxylates adsorb with their carboxyl group further from the surface, i.e., an applied electric field acting on the side-chain is screened by the solvent. This leads to reduced electric field effects and weaker adsorption in general. Current results provide a useful information, which may help to interpret complex electrokinetic phenomena.