Surface chemistry of alanine on Cu{111}: Adsorption geometry and temperature dependence

Baldanza, Silvia; Cornish, Alix; Nicklin, Richard E. J.; Zheleva, Zhasmina V.; Held, Georg

doi:10.1016/j.susc.2014.04.016

Cited by 17 publications

(37 citation statements)

References 44 publications

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“…25,26 Our recent work on the adsorption of chiral modifiers on Ni, Pt and Cu surfaces has shown that the combination of XPS and NEXAFS is very powerful in characterizing the adsorption complex in terms of chemical state, bond coordination and molecular orientation. 19,[27][28][29][30] These spectroscopies do not depend on long-range order and can even be applied under near-ambient pressure conditions. They are therefore well suited for the study of chiral modifiers and reactants on Ni surfaces.…”

Section: 24mentioning

confidence: 99%

Adsorption of Methyl Acetoacetate at Ni{111}: Experiment and Theory

et al. 2016

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Abstract. The hydrogenation of methyl acetoacetate (MAA) over modified Ni catalysts is one of the most important and best studied reactions in heterogeneous enantioselective catalysis. Yet, very little molecular-level information is available on the adsorption complex of the reactant.Here we report on a combined experimental and theoretical study of MAA adsorption on Ni{111}. XPS shows that the chemisorbed layer is stable up to 250 K; above 250 K decomposition sets in. In ultra-high vacuum conditions, multilayers grow below 150 K. DFT modelling predicts a deprotonated enol species with bidentate coordination on the flat Ni{111} surface. The presence of adatoms on the surface leads to stronger MAA adsorption in comparison with the flat surface, whereby the stabilization energy is high enough for MAA to 1 drive the formation of adatom defects at Ni{111}, assuming the adatoms come from steps.Comparison of experimental XPS and NEXAFS data with theoretical modeling, however, identify the bidentate deprotonated enol on the flat Ni{111} surface as the dominant species at 250 K, indicating that the formation of adatom adsorption complexes is kinetically hindered at low temperatures.

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Section: 24mentioning

confidence: 99%

Adsorption of Methyl Acetoacetate at Ni{111}: Experiment and Theory

et al. 2016

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“…While STM offers high resolution of the morphology of amino acids adsorbed on planar surfaces, obtaining direct data on the dynamics of nucleation and growth of patterns as a function of time is challenging. In many instances (but not all), X‐ray photoelectron spectroscopy (XPS) can serve as a complement to STM and NEXAFS spectroscopy, but does not overcome the limitations of these techniques. On the other hand, the combination of modeling with experimental characterization can offer a valuable alternative to overcoming these obstacles …”

Section: Introductionmentioning

confidence: 99%

Predictions of Pattern Formation in Amino Acid Adlayers at the In Vacuo Graphene Interface: Influence of Termination State

Awuah

Walsh

2019

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Controlled self‐assembly of biomolecules on graphene offers a pathway for realizing its full potential in biological applications. Microscopy has revealed the self‐assembly of amino acid adlayers into dimer rows on nonreactive substrates. However, neither the spontaneous formation of these patterns, nor the influence of amino acid termination state on the formation of patterns has been directly resolved to date. Molecular dynamics simulations, with the ability to reveal atomic level details and exert full control over the termination state, are used here to model initially disordered adlayers of neutral, zwitterionic, and neutral–zwitterionic mixtures for two types of amino acids, tryptophan and methionine, adsorbed on graphene in vacuo. The simulations of the zwitterion‐containing adlayers exhibit the spontaneous emergence of dimer row ordering, mediated by charge‐driven intermolecular interactions. In contrast, adlayers containing only neutral species do not assemble into ordered patterns. It is also found that the presence of trace amounts of water reduces the interamino acid interactions in the adlayers, but does not induce or disrupt pattern formation. Overall, the findings reveal the balance between the lateral interamino acid interactions and amino acid–graphene interactions, providing foundational insights for ultimately realizing the predictable pattern formation of biomolecules adsorbed on unreactive surfaces.

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“…7, 52,53 For adsorption on Ni{111}, however, the work by Ghiringhelli et al 54 suggests that alanine will adsorb via the N atom and a single carboxyl group O atom (the other O atom being protonated). Recent work by Baldanza et al 45 has highlighted the possibility of a bidentate Chemical State. Figure 1 shows the XP spectra recorded in 129 the C 1s, N 1s, and O 1s regions after L-alanine deposition onto 130 the surface at 250 and 300 K. Coverage calibration was per-131 formed via comparison of the O 1s and C 1s XPS signal areas with 132 those for a saturated CO layer of known coverage Θ = 0.57 ML 57 133 using an excitation energy of 950 eV (not shown).…”

Section: ■ Introductionmentioning

confidence: 99%

Surface Chemistry of Alanine on Ni{111}

et al. 2015

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The adsorption of L-alanine on Ni{111} has been studied as a model of enantioselective heterogeneous catalysts. Synchrotron-based X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy were used to determine the chemical state, bond coordination, and out-of-plane orientation of the molecule on the surface. Alanine adsorbs in anionic and zwitterionic forms between 250 and ≈320 K. NEXAFS spectra exhibit a strong angular dependence of the π* resonance associated with the carboxylate group, which is compatible with two distinct orientations with respect to the surface corresponding to the bidentate and tridentate binding modes. Desorption and decomposition begin together at ≈300 K, with decomposition occurring in a multistep process up to ≈450 K. Comparison with previous studies of amino acid adsorption on metal surfaces shows that this is among the lowest decomposition temperatures found so far and lower than typical temperatures used for hydrogenation reactions where modified Ni catalysts are used. 65 With increasing coverage, alanine begins to bind as the zwitterion 66 in a bidentate mode, with surface saturation at 0.25 ML and both 67 forms of alanine coexisting on the surface. Desorption and 68 decomposition are seen to begin together at around 300 K, with 69 decomposition occurring in a multistep process below 450 K. 70 NEXAFS spectra exhibit strong angular dependence of the π* 71 resonances associated with the carboxylate group, allowing the 72 establishment of two distinct orientations with respect to the 73 surface, which are presumed to correspond to the bidentate and 74 tridentate binding modes.

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Surface chemistry of alanine on Cu{111}: Adsorption geometry and temperature dependence

Cited by 17 publications

References 44 publications

Adsorption of Methyl Acetoacetate at Ni{111}: Experiment and Theory

Adsorption of Methyl Acetoacetate at Ni{111}: Experiment and Theory

Predictions of Pattern Formation in Amino Acid Adlayers at the In Vacuo Graphene Interface: Influence of Termination State

Surface Chemistry of Alanine on Ni{111}

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