Kinetics, Assembling, and Conformation Control of L-Cysteine Adsorption on Pt Investigated by in situ FTIR Spectroscopy and QCM-D.

Autor: Dourado AHB; Depto. Química Fundamental, Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes, 05508-080, São Paulo - SP, Brazil., Silva RA; Depto. Química Fundamental, Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes, 05508-080, São Paulo - SP, Brazil., Torresi RM; Depto. Química Fundamental, Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes, 05508-080, São Paulo - SP, Brazil., Sumodjo PTA; Depto. Química Fundamental, Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes, 05508-080, São Paulo - SP, Brazil., Arenz M; Chemistry Department, København Universitet, Universistetsparken 5, 2100, Copenhagen, Denmark.; Present Adress: Department of Chemistry and Biochemistry, Universität Bern, Freiestrasse 3 CH -, 3012, Bern, Switzerland., Cordoba de Torresi SI; Depto. Química Fundamental, Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes, 05508-080, São Paulo - SP, Brazil.
Jazyk: angličtina
Zdroj: Chemphyschem : a European journal of chemical physics and physical chemistry [Chemphyschem] 2018 Sep 18; Vol. 19 (18), pp. 2340-2348. Date of Electronic Publication: 2018 Jun 20.
DOI: 10.1002/cphc.201800380
Abstrakt: A quartz crystal microbalance method with dissipation (QCM-D) and attenuated total reflection Fourier-transform infrared (ATR-FTIRS) spectroscopy were used to study the adsorption of L-cysteine (L-Cys) on Pt. Through QCM-D, it was possible to verify that the viscoelastic properties of the adsorbed species play an important role in the adsorption, rendering Sauerbrey's equation inapplicable. The modelling of QCM-D data exposed two different processes for the adsorption reaction. The first one had an activation time and is fast, whereas the second is slow. These processes were also resolved by ATR-FTIRS and identified to be water and anion adsorption preceded by L-Cys adsorption. Both techniques reveal that the degree of surface coverage is pH dependent. Spectroscopic data indicate that the conformation of L-Cys (ads) changes with pH and that the structures do not fully agree with those proposed in literature for other metallic surfaces. The assembling of the adsorbed monolayer appeared to be very fast, and it was not possible to determine or quantify this kinetics. The conformation is also controlled by applied potential, and the anion adsorption and interfacial water depends on the conformation of the adsorbed molecules.
(© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)
Databáze: MEDLINE
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