Van der Waals Heteroepitaxy of Air-Stable Quasi-Free-Standing Silicene Layers on CVD Epitaxial Graphene/6H-SiC.

Graphene, consisting of an inert, thermally stable material with an atomically flat, dangling-bond-free surface, is by essence an ideal template layer for van der Waals heteroepitaxy of two-dimensional materials such as silicene. However, depending on the synthesis method and growth parameters, graphene (Gr) substrates could exhibit, on a single sample, various surface structures, thicknesses, defects, and step heights. These structures noticeably affect the growth mode of epitaxial layers, .

Improving Orientation, Packing Density, and Molecular Arrangement in Self-Assembled Monolayers of Bianchoring Ferrocene-Triazole Derivatives by "Click" Chemistry.

This work describes the self-assembled monolayers (SAMs) of two ferrocene derivatives with two anchoring groups (at the bottom and at the top of the SAM) deposited on ultraflat template-stripped gold substrates by cyclic voltammetry and analyzed by complementary surface characterization techniques. The SAM of each molecule is deposited by three different protocols: direct deposition (one step), click reaction on the surface (two steps), and reverse click reaction on the surface (two steps). The SAM structure is well studied to determine the SAM orientation, SAM arrangement, and ferrocene position within the SAM.

On-Surface Synthesis: A New Route Realizing Single-Layer Conjugated Metal-Organic Structures.

Recently, both experimental and theoretical advances have demonstrated that two-dimensional conjugated metal-organic frameworks (2D-cMOFs) exhibit interesting electronic and magnetic properties, such as high conductivity and ferromagnetism. Theoretical studies have predicted that exotic quantum states, including topological insulating states and superconductivity, emerge in some 2D-MOFs. The high design tunability of MOFs' structure and composition provides great opportunities to realize these structures.

Catalytic Scanning Probe Nanolithography (cSPL): Control of the AFM Parameters in Order to Achieve Sub-100-nm Spatially Resolved Epoxidation of Alkenes Grafted onto a Surface.

Scanning probe lithography (SPL) appears to be a reliable alternative to the use of masks in traditional lithography techniques as it offers the possibility of directly producing specific chemical functionalities with nanoscale spatial control. We have recently extend the range of applications of catalytic SPL (cSPL) by introducing a homogeneous catalyst immobilized on the apex of a scanning probe. Here we investigate the importance of atomic force microscopy (AFM) physical parameters (applied force, writing speed, and interline distance) on the resultant chemical activity in this cSPL methodology through the direct topographic observation of nanostructured surfaces.

Hierarchy of Chemical Bonding in the Synthesis of Fe-Phthalocyanine on Metal Surfaces: A Local Spectroscopy Approach.

Scanning tunneling spectroscopy (STS) has become a key tool for accessing properties of organometallic molecules adsorbed on surfaces. However, the rich variety of signatures makes it sometimes a difficult task to find out which feature is intrinsic to the molecule, i.e.

Growth of boronic acid based two-dimensional covalent networks on a metal surface under ultrahigh vacuum.

The formation of atomically precise covalent networks directly on a surface is a promising approach to produce single layers of two-dimensional organic materials (2D polymers). In the emerging field of on-surface synthesis, there is an urgent need for finding a rationale to new reaction pathways taking place directly on the surface. In this feature article we review and put into perspective recent results on the surface polymerisation of boronic acid based systems under ultrahigh vacuum conditions studied by scanning tunnelling microscopy.

Two-dimensional polymer as a mask for surface nanopatterning.

NaCl islands are used as a sacrificial layer to selectively deposit a boronic acid based two-dimensional polymer. The nanostructured polymer layer can be used as a negative mask to create Fe islands in a nanolithography mimicking process.

Tip- or electron beam-induced surface polymerization.

Control on the formation of a two-dimensional polymer could be achieved in two different ways. Manipulation with the tip of a scanning tunneling microscope allowed for assigning the localization of the polymerization reaction. Additionally, electron irradiation could accelerate greatly the reaction kinetics.

Single layer of polymeric Fe-phthalocyanine: an organometallic sheet on metal and thin insulating film.

Supramolecular chemistry on a surface has produced a large variety of atomically controlled systems, but practical applications are seriously restricted by the use of weakly cohesive non-covalent bonds and by the confinement to a metal surface. Here we report on the formation of a well-ordered organometallic sheet consisting of two-dimensional polymeric phthalocyanine. Remarkably, the growth demonstrated on a metal surface can be extended onto a thin insulating film.

Robust supramolecular network on Ag(111): hydrogen-bond enhancement through partial alcohol dehydrogenation.

Alcohol oxidation and self-assembly: the in situ oxidation of hydroxyl functional groups to quinone groups promotes the formation of enhanced hydrogen bonds and allows reorganization of the resulting supramolecular self-assemblies, which evolve from a weakly bound dense phase to a strongly bound nanoporous open structure (see picture).

Organized formation of 2D extended covalent organic frameworks at surfaces.

The development of nanoscale masking for particle deposition is exceedingly important to push the future of nanoelectronics beyond the current limits of lithography. We present the first example of ordered hexagonal covalent nanoporous structures deposited in extended arrays of near monolayer coverage across a Ag(111) surface. The networks were formed from the deposition of the reagents from a heated molybdenum crucible between 370 and 460 K under ultrahigh vacuum (UHV) onto a cleaned Ag(111) substrate and imaged using a scanning tunneling microscope (STM).

Influence of chlorine substitution on the self-assembly of zinc phthalocyanine.

The adsorption and ordering of zinc phthalocyanine (ZnPc) and octachloro zinc phthalocyanine (ZnPcCl(8)) on an Ag(111) surface is studied in situ by scanning tunneling microscopy under ultrahigh vacuum. Two-dimensional self-assembled supramolecular domains are observed for these two molecules. We show how substituting chlorine atoms for half of the peripheral hydrogen atoms on ZnPc influences the self-assembly mechanisms.

Direct observation of chiral metal-organic complexes assembled on a Cu100 surface.

We report single-molecule level STM observations of chiral complexes generated by the assembly of achiral components at a metal surface. Following co-deposition of iron atoms and 1,3,5-tricarboxylic benzoic acid (trimesic acid, TMA) on Cu(100) in ultrahigh vaccum, TMA molecules react with the metal centers, and metal-ligand interactions stabilize R and S chiral complexes which are clearly distinguished by STM.