Surface Confined Hydrogenation of Graphene Nanoribbons.

On-surface synthesis with designer precursor molecules is considered an effective method for preparing graphene nanoribbons (GNRs) of well-defined widths and with tunable electronic properties. Recent reports have shown that the band gap of ribbons doped with heteroatoms (such as boron, nitrogen, and sulfur) remains unchanged in magnitude in most cases. Nevertheless, theory predicts that a tunable band gap may be engineered by hydrogenation, but experimental evidence for this is so far lacking.

Highly Ordered N-Heterocyclic Carbene Monolayers on Cu(111).

The benzannulated N-heterocyclic carbene, 1,3-dibenzylbenzimidazolylidene (NHC) forms large, highly ordered domains when adsorbed on Cu(111) under ultrahigh vacuum conditions. A combination of scanning tunnelling microscopy (STM), high-resolution electron energy loss spectroscopy (HREELS), and density functional theory (DFT) calculations reveals that the overlayer consists of vertical benzannulated NHC moieties coordinating to Cu adatoms. Long-range order results from the placement of the two benzyl substituents on opposite sides of the benzimidazole moiety, with their aromatic rings approximately parallel to the surface.

N-Heterocyclic Carbenes Reduce and Functionalize Copper Oxide Surfaces in One Pot.

Benzimidazolium hydrogen carbonate salts have been shown to act as N-heterocyclic carbene precursors, which can remove oxide from copper oxide surfaces and functionalize the resulting metallic surfaces in a single pot. Both the surfaces and the etching products were fully characterized by spectroscopic methods. Analysis of surfaces before and after NHC treatment by X-ray photoelectron spectroscopy demonstrates the complete removal of copper(II) oxide.

Tuning Pd-nanoparticle@MIL-101(Cr) Catalysts for Tandem Reductive Amination.

Abstract: The versatility of MOFs as highly porous Lewis acidic supports for precious metal nanoparticles has been exploited for one-pot tandem reductive amination catalysis. MIL-101(Cr) loaded with Pd nanoparticles ca. 3 nm in size at 0.

N-Heterocyclic Carbene Self-assembled Monolayers on Copper and Gold: Dramatic Effect of Wingtip Groups on Binding, Orientation and Assembly.

Self-assembled monolayers of N-heterocyclic carbenes (NHCs) on copper are reported. The monolayer structure is highly dependent on the N,N-substituents on the NHC. On both Cu(111) and Au(111), bulky isopropyl substituents force the NHC to bind perpendicular to the metal surface while methyl- or ethyl-substituted NHCs lie flat.

Simple direct formation of self-assembled N-heterocyclic carbene monolayers on gold and their application in biosensing.

The formation of organic films on gold employing N-heterocyclic carbenes (NHCs) has been previously shown to be a useful strategy for generating stable organic films. However, NHCs or NHC precursors typically require inert atmosphere and harsh conditions for their generation and use. Herein we describe the use of benzimidazolium hydrogen carbonates as bench stable solid precursors for the preparation of NHC films in solution or by vapour-phase deposition from the solid state.

Fabrication of a High-Quality, Porous, Surface-Confined Covalent Organic Framework on a Reactive Metal Surface.

A major goal of heterogeneous catalysis is to optimize catalytic selectivity. Selectivity is often limited by the fact that most heterogeneous catalysts possess sites with a range of reactivities, resulting in the formation of unwanted by-products. The construction of surface-confined covalent organic frameworks (sCOFs) on catalytically active surfaces is a desirable strategy, as pores can be tailored to operate as catalytic nanoreactors.

Formation of bioinorganic complexes by the corrosive adsorption of (S)-proline on Ni/Au(111).

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.

Assembly of a chiral amino acid on an unreactive surface: (S)-proline on Au(111).

The adsorption of (S)-proline on Au(111) at 300 K was studied by low-temperature scanning tunnelling microscopy, X-ray photoelectron spectroscopy, and high resolution electron energy loss spectroscopy. (S)-proline adsorbs to produce a 2-D gas phase at 300 K, which can be condensed to form ordered molecular assemblies on cooling to 77 K. The chemical nature of the self-assembled structures is discussed in light of the information provided by photoelectron and vibrational spectroscopies.

Chiral recognition at one-dimensional metal-organic coordination networks initiates the ordering of prochiral catalytic reagent methylacetoacetate on Au{111}.

A scanning tunnelling microscopy investigation is reported of the adsorption of methylacetoacetate on Au{111} surfaces templated by the growth of 1-D chains of nickel pyroglutamate. The symmetry of the Au{111}-herringbone reconstruction and the chirality of the pyroglutamate species influence the preferred growth directions of pyroglutamate chains. The interaction of methylacetoacetate with the various chain types reveals details of the symmetry and conformation of the chains.

Coupling of triamines with diisocyanates on Au(111) leads to the formation of polyurea networks.

The surface-confined coupling reaction between melamine (1,3,5-triazine-2,4,6-triamine) and 1,4-phenylene diisocyanate has been investigated on Au(111) by scanning tunneling microscopy. Diisocyanate species are stabilized at the edges of melamine arrays and coupling reactions to form small urea oligomers may be initiated at room temperature. These oligomers are incorporated into the two-dimensional melamine array.

Self-assembly of semifluorinated n-alkanethiols on {111}-oriented Au investigated with scanning tunneling microscopy experiment and theory.

The adsorption of semifluorinated alkanethiols on Au/mica was studied by scanning tunneling microscopy (STM). The adlayer structure produced is based on a p(2 x 2) structure though lines of molecules displayed extensive kinks and bends. In addition, a considerable variation in the contrast of molecular features is found.

Local and global chirality at surfaces: succinic acid versus tartaric acid on Cu110.

A detailed comparison of tartaric acid (HOOC-CHOH-CHOH-COOH) and succinic acid (HOOC-CH(2)-CH(2)-COOH) molecules on a Cu(110) surface is presented with a view to elucidate how the two-dimensional chirality exhibited by such robust, chemisorbed systems is affected when both OH groups of the former molecule are replaced with H groups, a stereochemical change that leaves the metal-bonding functionalities of the molecule untouched but destroys both chiral centers. It is found that this change does not significantly affect the thermodynamically preferred chemical forms that are adopted, namely the doubly deprotonated bicarboxylate at low coverages (theta View Article and Find Full Text PDF