Structure and stability of thioureate anions with water, DFT calculations

Yang, Wen; Zhou, Wei; Peng, Ke

doi:10.1016/j.theochem.2008.02.024

Cited by 3 publications

(2 citation statements)

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“…The experimental results on the adsorption of TU at metal electrodes can be compared with those derived from density functional theory (DFT) calculations, ,− In this respect, some reports exist regarding the theoretical study of the microsolvation of TU and thioureate anions (CSNH 2 NH – ) with up to 6 and 7 water molecules, respectively, and the effects on structure and energetics. The interaction of TU and urea with different anions was studied by B3LYP/6-311+G** calculations, as these molecules or their derivatives have the potential to be used in the identification of anions in biological systems .…”

Section: Introductionmentioning

confidence: 99%

Spectroelectrochemical and DFT Study of Thiourea Adsorption on Gold Electrodes in Acid Media

et al. 2014

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The adsorption of thiourea (TU) at Au(111) and Au(100) single crystal and evaporated gold thin-film electrodes with preferential (111) orientation was studied in perchloric acid solutions with TU concentrations below 0.1 mM. For this purpose, cyclic voltammetry with gold single crystals was combined with external reflection infrared spectroscopy and surface-enhanced infrared reflection−absorption spectroscopy under attenuated total reflection conditions (ATR-SEIRAS) with gold thin film electrodes. In situ surface enhanced Raman spectroscopy (SERS) experiments were also carried out with these latter samples. In addition, optimized geometries and theoretical harmonic vibrational frequencies, obtained from B3LYP/LANL2DZ, 6-31+G(d) calculations for TU and thioureate species adsorbed on Au clusters with (111) orientation, were used for the interpretation of the experimental spectra. ATR-SEIRAS experiments show irreversible adsorption of TU at 0.10 V, whereas the SERS experiments have confirmed the bonding of the TU molecule to the metal surface through the S atom. The optimized geometry obtained from density functional theory (DFT) calculations for adsorbed TU corresponds to unidentate bonding through the sulfur atom, with the Au−S bond slightly tilted (13°) from the surface normal, whereas the C−S bond appears to be tilted by 45°. In the case of adsorbed thioureate, under the application of an external electric field of 0.01 a.u., a bidentate asymmetrical bridge adsorption configuration is obtained with one N(H) and the S atoms bonded to Au in positions close to "top" adsorption sites and with the molecular plane perpendicular to the metal surface. The observation of an adsorbate band for the asymmetric NCN stretching in the experimental infrared spectra confirms the tilting of the S−C bond of the adsorbed TU at low potentials. Changes of the adsorbate bands in the ATR-SEIRA spectra at potentials around 0.60 vs reversible hydrogen electrode (RHE) can be interpreted on the basis of DFT results as due to the deprotonation of adsorbed TU to form adsorbed thioureate.

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Section: Introductionmentioning

confidence: 99%

Spectroelectrochemical and DFT Study of Thiourea Adsorption on Gold Electrodes in Acid Media

et al. 2014

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“…The nature water exist in the form of liquid water molecule clusters, the smallest water cluster in nature is associated by 6 water molecules [4], it is commonly called hexagonal water. The typical hexagonal water is glacial water.…”

Section: Preparation Of An Anion Water 11 Generation Mechanism Of Ani...mentioning

confidence: 99%

The Latest Developments and Applications of Anion Water

Wei¹,

et al. 2014

AMR

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On the electrochemical behavior of formamidine disulfide on gold electrodes in acid media

Cheuquepán

Orts

Rodes

2016

Journal of Electroanalytical Chemistry

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Please cite this article as: William Cheuquepán, José Manuel Orts, Antonio Rodes, On the electrochemical behavior of formamidine disulfide on gold electrodes in acid media, Journal of Electroanalytical Chemistry (2016Chemistry ( ), doi: 10.1016Chemistry ( /j.jelechem.2016 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT ABSTRACTThe adsorption and reactivity of formamidine disulfide (FDS) was studied at gold single crystal and thin film electrodes in perchloric acid solutions and the results of cyclic voltammetry and in situ infrared spectroscopy (SNIFTIR and ATR-SEIRAS) experiments compared with those previously obtained with thiourea (TU). In addition, optimized geometries and theoretical harmonic vibrational frequencies were obtained for adsorbed FDS, TU and thioureate from plane-wave DFT calculations using periodic surface models. These results were compared in the case of TU and thioureate to those previously obtained with a model Au cluster surface with (111) orientation. In the case of FDS, weak adsorption takes place with the S-S bond essentially parallel to the metal surface. No specific bands for adsorbed FDS can be identified in the experimental ATR-SEIRA spectra. These latter spectra suggest that adsorbed thioureate species are spontaneously formed upon dissociative adsorption of FDS when dosing this molecule at open circuit. Some of the adsorbed thioureate species undergo reductive protonation giving rise to a mixed adlayer formed by adsorbed thioureate and thiourea in a surface process which is faster when a controlled potential of 0.70 V is applied. In agreement with the observations reported when dosing TU, the ratio between TU and thioureate adsorbates is found to depend on the electrode potential, being higher for potentials close to the hydrogen evolution limit and decreasing for higher potential values. A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT2 Graphical AbstractHighlights -FDS adsorbs weakly on Au with Au-S distances longer than those for TU and thioureate.-Physisorbed FDS dissociates homolitically to yield adsorbed thioureate.-Some adsorbed thioureate species are reduced to adsorbed thiourea.-Dosing conditions influence the rate of formation of adsorbed thiourea.-The thiourea/thioureate adsorbate ratio depends on the applied potential.

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Structure and stability of thioureate anions with water, DFT calculations

Cited by 3 publications

References 25 publications

Spectroelectrochemical and DFT Study of Thiourea Adsorption on Gold Electrodes in Acid Media

Spectroelectrochemical and DFT Study of Thiourea Adsorption on Gold Electrodes in Acid Media

The Latest Developments and Applications of Anion Water

On the electrochemical behavior of formamidine disulfide on gold electrodes in acid media

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