Molecular sinkers : x-ray photoemission and atomistic simulations of benzoic acid and benzoate at the aqueous solution/vapor interface
Ottosson, Niklas and Romanova, Anastasia O. and Soderstrom, Johan and Bjorneholm, Olle and Ohrwall, Gunnar and Fedorov, Maxim V. (2012) Molecular sinkers : x-ray photoemission and atomistic simulations of benzoic acid and benzoate at the aqueous solution/vapor interface. Journal of Physical Chemistry B, 116 (43). pp. 13017-13023. ISSN 1520-6106 (https://doi.org/10.1021/jp300956j)
Full text not available in this repository.Request a copyAbstract
In this work, we provide a detailed microscopic picture of the behavior of benzoic acid at the aqueous solution/vapor interface in its neutral as well as in its dissociated form (benzoate). This is achieved through a combination of highly surface-sensitive X-ray photoelectron spectroscopy experiments and fully atomistic molecular simulations. We show that significant changes occur in the interface behavior of the neutral acid upon release of the proton. The benzoic acid molecules are found to be strongly adsorbed at the interface layer with the planes of the aromatic rings oriented almost parallel to the water surface. In contrast, in the benzoate form, the carboxylate group shows a sinker-like behavior while the aromatic ring acts as a buoy, oriented nearly perpendicular to the surface. Furthermore, a significant fraction of the molecular ions move from the interface layer into the bulk of the solution. We rationalize these findings in terms of the very different hydration properties of the carboxylic group in the two charge states. The molecule has an amphiphilic nature, and the deprotonation thus changes the hydrophobic/hydrophilic balance between the nonpolar aromatic and the polar carboxylic parts of the molecule. That, consequently, leads to a pronounced reorientation and depletion of the molecules at the interface.
-
-
Item type: Article ID code: 42908 Dates: DateEvent1 November 2012PublishedSubjects: Science > Physics Department: Faculty of Science > Physics
Technology and Innovation Centre > BionanotechnologyDepositing user: Pure Administrator Date deposited: 19 Feb 2013 10:06 Last modified: 08 Apr 2024 20:21 Related URLs: URI: https://strathprints.strath.ac.uk/id/eprint/42908