The influence of aliphatic amines on the potential of the structural transition (hex) → (1 × 1) for Au (100) electrode

Abstract

The impact of the aliphatic amines on the potential (E T ) of the structural transition (hex) ? (1 9 1) for Au (100) electrode was investigated. This potential was shifted to more negative values as the concentration of a given amine increased. As E T depends linearly on the log of the bulk concentration for each amine it was suggested to use this relationship for quantitative determination of the amines. Moreover, it was shown that the presence of amines reduced the stability range of the (hex) structure in the following sequence methylamine \ ethylamine \ propylamine \ butylamine due to their increasing adsorbability. Furthermore, for a given concentration the introduction of each subsequent -CH 2 -group into the carbon chain of an amine is accompanied by the reduction of the stability range of ca. 23 mV.

First-Principles-Based Force Field for the Interaction of Proteins with Au(100)(5 × 1): An Extension of GolP-CHARMM

“…Out of the molecules tested, only imidazole and water can be anticipated to promote deconstruction of the Au(100)(5 × 1) surface in vacuo (SI, Figure S10). Experimental work investigating the influence of adsorbates on Au(100) surface reconstruction has thus far focused on their effect on potential-induced reconstruction under aqueous conditions ,− and not surface stability in vacuo, as modeled here. As discussed in the “Amino Acid Simulations”, the difference in binding affinity, Δ E ads(1×1) – Δ E ads(5×1) , of an adsorbate in the presence of liquid water is likely to be distinctly different from that in vacuo.…”

“…While the orientation of interfacial water molecules very close to the gold surface was slightly more ambivalent at the corrugated aqueous−Au(100)(5 × 1) interface than either of the topologically flat, Au (111) or Au(100)(1 × 1), surfaces 33 (SI, Figure S5a,b), that of waters within the first adsorbed layer as a whole was comparable at all three interfaces (SI, Figure S5c). This is expected since small undulations in an inorganic surface, such as those observed due to the reconstruction of the Au(100) surface, are only large enough to disrupt the regular packing of interfacial water molecules immediately adjacent to the interface.…”

“…In its relaxed structure the interface is buckled due the spatial mismatch between surface and underlying Au atoms. In contrast, the Au (111) surface is topologically flat, but like the Au(100)(5 × 1) surface, the gold atoms are also arranged in a hexagonal array. The degree of surface corrugation is in good agreement with experiment (see "Au(100)(5 × 1) Surface").…”

“…These parameters, namely, for sp 2 hybridized carbon and oxygen and for hydrogen (hydroxyl or amide H only) atoms, apply only to the homogeneous hollow interaction sites, AUIU, and were required to correct the interaction energies of aromatic and O-containing species with gold, relative to PW-DFT data. As with the Au (111) and Au(100)(1 × 1) surfaces, a refined Au− Au potential for sp 2 -hybridized carbon atoms present in aromatic rings was fit to benzene adsorption. In the absence of this correction, the adsorption of benzene to the Au(100) (5 × 1) surface was underestimated by 5%.…”

“…Recent firstprinciples MD simulations of the aqueous−Au (111) interface identified an enhanced tendency for interfacial waters to act as hydrogen bond donors. 99,100 Although, to date, no firstprinciples simulations of the aqueous−Au(100)(5 × 1) interface exist to confirm or refute our predictions, the spatial similarities (geometrical arrangement of atoms and atomic surface density) between the Au(100)(5 × 1) and Au (111) surfaces suggest it is reasonable to make this assumption. 101 In addition, the energetic preference for a tilted, relative to an Odown, water−gold geometry using vdW-DF was small (0.9 and 2.4 kJ mol −1 at T1 and T2 sites, respectively).…”