Surface-Altered Protonation Studied by Photoelectron Spectroscopy and Reactive Dynamics Simulations

The extent to which functional groups are protonated at aqueous interfaces as compared to bulk is deemed essential to several areas in chemistry and biology. The origin of such changes has been the source of intense debate. We use X-ray photoelectron spectroscopy and all-atom reactive molecular dyna...

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Bibliographic Details
Published in:The journal of physical chemistry letters Vol. 6; no. 5; pp. 807 - 811
Main Authors: da Silva, Áderson Miranda, Mocellin, Alexandra, Monti, Susanna, Li, Cui, Marinho, Ricardo R. T, Medina, Aline, Agren, Hans, Carravetta, Vincenzo, de Brito, Arnaldo Naves
Format: Journal Article
Language:English
Published: United States American Chemical Society 05-03-2015
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Summary:The extent to which functional groups are protonated at aqueous interfaces as compared to bulk is deemed essential to several areas in chemistry and biology. The origin of such changes has been the source of intense debate. We use X-ray photoelectron spectroscopy and all-atom reactive molecular dynamics simulations as two independent methods to probe, at the molecular scale, both bulk and surface distributions of protonated species of cysteine in an aqueous solution. We show that the distribution of the cysteine species at the surface is quite different from that in the bulk. We argue that this finding, however, cannot be simply related to a change in the extent of proton sharing between the two conjugate acid/base pairs that may occur between these two regions. The present theoretical simulations identify species at the surface that are not present in the bulk.
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ISSN:1948-7185
1948-7185
DOI:10.1021/acs.jpclett.5b00131