The Study of Chiral Adsorption Systems Using Synchrotron-Based Structural and Spectroscopic Techniques: Stereospecific Adsorption of Serine on Au-Modified Chiral Cu{531} Surfaces

Abstract

We apply modern synchrotron-based structural techniques to the study of serine adsorbed on the pure and Aumodified intrinsically chiral Cu{531} surface. XPS and NEXAFS data in combination with DFT show that on the pure surface both enantiomers adsorb in l 4 geometries (with de-protonated b-OH groups) at low coverage and in l 3 geometries at saturation coverage. Significantly larger enantiomeric differences are seen for the l 4 geometries, which involve substrate bonds of three side groups of the chiral center, i.e. a three-point interaction. The l 3 adsorption geometry, where only the carboxylate and amino groups form substrate bonds, leads to smaller but still significant enantiomeric differences, both in geometry and the decomposition behavior. When Cu{531} is modified by the deposition of 1 and 2 ML Au the orientations of serine at saturation coverage are significantly different from those on the clean surface. In all cases, however, a l 3 bond coordination is found at saturation involving different numbers of Au atoms, which leads to relatively small enantiomeric differences.

Adsorption and self-assembly of bio-organic molecules at model surfaces: A route towards increased complexity

“…Therefore it may orient close to the surface and establish a fourth binding point with it. This is the 4 conformation observed, e.g., for Lys/Cu(110) [152] and Ser/Cu(531) [144]. The similarity in the adsorption conformation leads for these molecules to very similar long range adsorption patterns, as demonstrated by LEED and STM.…”

“…Synchrotron-based structural techniques where applied also to the study of serine adsorbed on the pure and Au modified Cu(531) surface [144]. Combination of LEED, XPS, NEXAFS and DFT results shows that: i) Enantiomeric differences between (D)-Ser and (L)-Ser exist in both cases.…”

Chiral selectivity of amino acid adsorption on chiral surfaces—The case of alanine on Pt

“…[17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] Among the most widely studied chiral systems are simple amino acids on naturally chiral metal surfaces. [20,28,29,[32][33][34][35][36] A lot of experimental and computational studies were dedicated to amino acids on Cu surfaces, [20,28,[32][33][34][36][37][38][39][40][41][42][43][44][45][46] but also on Pd, Pt and Au surfaces. [28,44,[46][47][48][49][50] On Cu it was found that the carboxyl group of amino acids is deprotonated and the molecule adsorbs on most surfaces in a "tridentate" fashion, i.e.…”

Tuning the Surface Chemistry of Chiral Cu(531)S for Enhanced Enantiospecific Adsorption of Amino Acids

“…The decoration of the kink site with the other metal may induce the larger enantiomeric differences. 37,39,40 Eralp et al reported that the angle between the [112̅ ] direction of Cu{531} and the surface projection of the normal of the carboxylate O−C−O triangle of serine is significantly changed upon Au-modification of Cu{531}. 37 Our previous works also showed that decorating the kink site can provide a potential to elevate the enantiospecificity of amino acids on intrinsically chiral surfaces.…”