title: Formation of bioinorganic complexes by the corrosive adsorption of (S)-proline on Ni/Au(111).
abstract: 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 tunneling 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.
authors.affiliation: EaStCHEM School of Chemistry, University of St. Andrews , St. Andrews, Fife KY16 9ST, U. K.
authors.forename: Riho T
authors.initials: RT
authors.lastname: Seljamäe-Green
authors.forename: Grant J
authors.initials: GJ
authors.lastname: Simpson
authors.forename: Federico
authors.initials: F
authors.lastname: Grillo
authors.forename: John
authors.initials: J
authors.lastname: Greenwood
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Francis
authors.forename: Renald
authors.initials: R
authors.lastname: Schaub
authors.forename: Jerome E
authors.initials: JE
authors.lastname: Gano
authors.forename: Herbert A
authors.initials: HA
authors.lastname: Früchtl
authors.forename: Paolo
authors.initials: P
authors.lastname: Lacovig
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Baddeley
mesh_terms: D000327:Adsorption; D056831:Coordination Complexes / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D016252:Microscopy, Scanning Tunneling; D015394:Molecular Structure; D009532:Nickel / Q000737:chemistry*; D011392:Proline / Q000737:chemistry*; D011761:Pyrrolidonecarboxylic Acid / Q000737:chemistry; D011789:Quantum Theory
chemical_list: D056831:Coordination Complexes; D006046:Gold; D009532:Nickel; D011392:Proline; D011761:Pyrrolidonecarboxylic Acid