Formation of bioinorganic complexes by the corrosive adsorption of (S)-proline on Ni/Au(111)
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Nickel nanoparticles modified by the adsorption of chiral amino acids are known to be effective enantioselective heterogeneous catalysts. The leaching of nickel by amino acids has a number of potential effects including the induction of chirality in the nickel atoms left behind in the nanoparticle and the creation of catalytically active nickel complexes. The adsorption of (S)-proline onto Au(111) precovered by two dimensional nickel nanoclusters was investigated by scanning tunnelling microscopy, X-ray photoelectron spectroscopy and high resolution electron energy loss spectroscopy. Adsorption of (S)-proline at 300 K resulted in the corrosion of the nickel clusters, the oxidation of the leached nickel and the on-surface formation of bioinorganic complexes, which are concluded to contain three prolinate species in an octahedral arrangement around the central Ni ion. Two distinguishable forms of nickel prolinate complexes were identified. One form self-assembles into 1-D chains and the other form gives rise to porous 2-D islands. Octahedral complexes of the type M(AB)3 are intrinsically chiral resulting in two pairs of enantiomers. The mirror symmetry of each pair of enantiomers is broken when, as in this study, the bidentate ligand itself possesses a chiral center. DFT calculations are used to examine the relative energies of each Ni(prolinate)3 complex as isolated gas phase species and isolated adsorbed species.
Green , R T S , Simpson , G J , Grillo , F , Greenwood , J , Francis , S M , Schaub , R , Gano , J E , Fruchtl , H A , Lacovig , P & Baddeley , C J 2015 , ' Formation of bioinorganic complexes by the corrosive adsorption of (S)-proline on Ni/Au(111) ' Langmuir , vol 31 , no. 1 , pp. 262–271 . DOI: 10.1021/la504236w
This document is the Accepted Manuscript version of a Published Work that appeared in final form in Langmuir, © 2014 American Chemical Society, after peer review and technical editing by the publisher. To access the final edited and published work see http://dx.doi.org/10.1021/la504236w
R.T.S.G. and J.G. acknowledge the Engineering and Physical Sciences Research Council (EPSRC, UK) for the award of a PhD studentship. The research leading to these results has received funding from the European Community’s Seventh Framework Programme (FP7/2007-2013) under grant agreement no. 312284. Date of Acceptance 15/12/2014
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