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Titolo:
Electrochemical and FTIR studies of L-phenylalanine adsorption at the Au(111) electrode
Autore:
Li, HQ; Chen, AC; Roscoe, SG; Lipkowski, J;
Indirizzi:
Univ Guelph, Guelph Waterloo Ctr Grad Study Chem, Guelph, ON N1G 2W1, Canada Univ Guelph Guelph ON Canada N1G 2W1 udy Chem, Guelph, ON N1G 2W1, Canada Acadia Univ, Dept Chem, Wolfville, NS B0P 1X0, Canada Acadia Univ Wolfville NS Canada B0P 1X0 em, Wolfville, NS B0P 1X0, Canada
Titolo Testata:
JOURNAL OF ELECTROANALYTICAL CHEMISTRY
fascicolo: 1-2, volume: 500, anno: 2001,
pagine: 299 - 310
Fonte:
ISI
Lingua:
ENG
Soggetto:
TRANSFORM INFRARED-SPECTROSCOPY; IN-SITU FTIR; SOLUTION INTERFACE; AMINO-ACIDS; 4-CYANOPYRIDINE ADSORPTION; SURFACE ELECTROCHEMISTRY; PLATINUM-ELECTRODES; BENZOATE ADSORPTION; OXIDATION REACTIONS; AQUEOUS-SOLUTION;
Keywords:
adsorption; infrared spectroscopy; L-phenyalanine; amino acid; gold electrodes;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
52
Recensione:
Indirizzi per estratti:
Indirizzo: Lipkowski, J Univ Guelph, Guelph Waterloo Ctr Grad Study Chem, Guelph Campus, Guelph, ON N1G 2W1, Canada Univ Guelph Guelph Campus Guelph ON Canada N1G 2W1 W1, Canada
Citazione:
H.Q. Li et al., "Electrochemical and FTIR studies of L-phenylalanine adsorption at the Au(111) electrode", J ELEC CHEM, 500(1-2), 2001, pp. 299-310

Abstract

The adsorption of L-phenylalanine (Phe) at the Au(111) electrode surface has been studied using electrochemical techniques and subtractively normalized interfacial Fourier transform infrared (SNIFTIR) techniques. The electrochemical measurements of cyclic voltammetry, differential capacity and chronocoulometry were used to determine Gibbs energies of adsorption and the reference (E-1) and sample (E-2) potentials to be used in the spectroscopic measurements. The vibrational spectra have been used to determine: (i) the orientation of the molecule at the surface as a function of potential; (ii) the dependence of the band intensity on the surface coverage; (iii) the character of surface coordination, and (iv) the oxidation of adsorbed Phe molecules at positive potentials. The adsorption of Phe is characterized by DeltaG values ranging from - 18 to - 37 kJ mol(-1) that are characteristic fora weak chemisorption of small aromatic molecules. The electrochemical and SNIFTIR measurements indicated that adsorbed Phe molecules change orientation as a function of applied potential. At the negatively charged surface Phe is predominantly adsorbed in the neutral form of the amino acid. At potentials positive to the pzc, adsorption occurs predominantly in the zwitterionic form with the -COO- group directed towards the surface and the ammoniumgroup towards the solution. At more positive potentials electrocatalytic oxidation of Phe occurs and is marked by the appearance of the CO2 asymmetric stretch band in the FTIR spectrum. Thus, relative to pzc, Phe is weakly chemisorbed at negative potentials, changes orientation at potentials close to the pzc and is oxidized at positive potentials. (C) 2001 Elsevier Science B.V. All rights reserved.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 10/07/20 alle ore 15:00:00