The adsorption of 1,3,5-Benzenetricarboxylic (Trimesic) Acid (TMA) to a single crystal graphite surface has been studied under Ultra High Vacuum conditions. This work focuses on inducing particular self-assembly structure by OMBE (Organic Molecular Beam Epitaxy), characterized periodic non-dense-packing the molecules. Two coexisting phases could be imaged with sub-molecular resolution STM. Induced directed hydrogen bonding, organic molecules built in both cases two-dimensional grid...

The on surface synthesis of a two-dimensional (2D) covalent organic framework from halogenated aromatic monomer under ultra-high vacuum conditions is shown to be dependent the choice substrate.

We present the synthesis of a two-dimensional polymer at air/water interface and its nm-resolution imaging. Trigonal star, amphiphilic monomers bearing three anthraceno groups on central triptycene core are confined interface. Compression followed by photopolymerization provides polymer. Analysis scanning tunneling microscopy suggests that is periodic with ultrahigh pore density.

On-surface Ullmann coupling is a versatile and appropriate approach for the bottom-up fabrication of covalent organic nanostructures. In two-dimensional networks, however, kinetically controlled irreversible leads to high defect densities lack long-range order. To derive general guidelines optimizing reaction parameters, structural quality 2D porous networks was evaluated different preparation protocols. For this purpose, polymerization an iodine- bromine-functionalized precursor studied on...

Surface-assisted Ullmann coupling is both drosophila and workhorse of on-surface synthesis. The fabrication novel covalent low-dimensional organic nanostructures accompanied by fundamental studies surface chemistry.

A scanning tunneling microscope operated under ambient conditions was utilized to study the self-assembly of trimesic acid (TMA) at liquid-solid interface. On a graphite substrate, two different open, loosely packed, two-dimensional hydrogen-bond networks were found. Both structures exhibit periodic arrangement approximately 1.0 nm wide cavities, which can be used for co-adsorption another species (guest) within cells this host system. These polymorphs ("chickenwire" and "flower" structures)...

We present a variable-temperature study of monolayer self-assembly at the liquid−solid interface. By means in situ scanning tunneling microscopy (STM), reversible phase transitions from nanoporous low-temperature to more densely packed high-temperature are observed. The occurrence transition and respective temperature were found depend on type solvent solute concentration. Estimates entropic cost enthalpic gain upon suggest that coadsorption molecules within cavities structure renders this...

A two-dimensional molecular template structure of 1,3,5-benzenetricarboxylic acid (trimesic acid, TMA) was formed on a highly oriented pyrolytic graphite surface (HOPG) by self-assembly at the liquid−solid interface. Scanning tunneling microscopy (STM) investigations show high-resolution images porous surface. After host created, coronene molecules were inserted as guest into pores. STM results indicate that some rotate inside their bearing. Further single can be directly kicked out pores means STM.

Two different straightforward synthetic approaches are presented to fabricate long-range-ordered monolayers of a covalent organic framework (COF) on an inert, catalytically inactive graphite surface. Boronic acid condensation (dehydration) is employed as the polymerization reaction. In first approach, monomer prepolymerized by mere thermal treatment into nanocrystalline precursor COFs. The precursors then deposited drop-casting onto substrate and characterized scanning tunneling microscopy...

This work presents a scanning tunneling microscopy (STM) based study of benzenetribenzoic acid (BTB) monolayer structures at the liquid-solid interface. On graphite(0001) tailored molecules self-assemble into 2D supramolecular host systems, suitable for incorporation other nanoscopic objects. Two crystallographically different BTB were found-both hydrogen bonded networks. A specific structure was deliberately selected by solvent identity. One polymorphs is 6-fold chicken-wire with circular,...

Two-dimensional (2D) supramolecular self-assembly of various organic molecules at the liquid−solid interface is presented and discussed with a focus on compounds that are primarily functionalized by carboxylic groups. The main analytical tool utilized scanning tunneling microscopy (STM), high-resolution real-space technique capable readily providing full crystallographic information (i.e., not only lattice parameters but also number, type, orientation within unit cell). Carboxylic groups...

On-surface self-condensation of 1,4-benzenediboronic acid was previously shown to yield extended surface-supported, long-range-ordered two-dimensional covalent organic frameworks (2D COFs). The most important prerequisite for obtaining high structural quality is that the polycondensation (dehydration) reaction carried out under slightly reversible conditions, i.e., in presence water. Only then can subtle balance between kinetic and thermodynamic control be favorably influenced, defects are...

This scanning tunneling microscopy (STM) study uses a supramolecular two-dimensional architecture of trimesic acid molecules adsorbed on graphite substrate as host for the incorporation C60 molecular guest. By choosing proper solvent, it was possible to verify that self-assembly host−guest structure can be accomplished at liquid solid interface. Because ideal steric match with bearing structure, buckminster fullerenes are feasible guests. It coadsorb within cavities open TMA from phase, and...

Coadsorption of two different carboxylic acids, benzenetribenzoic acid and trimesic acid, was studied at the liquid-solid interface in solvents (heptanoic nonanoic acid). Independent alteration both concentrations binary solutions resulted six nondensely packed monolayer phases with structures stoichiometries, as revealed by means scanning tunneling microscopy (STM). All these are stabilized intermolecular hydrogen bonding between functional groups. Moreover, phase transitions structures,...

The role of organometallic intermediates during on-surface polymerization via Ullmann coupling was studied on Ag(111). progress monitored by X-ray photoelectron spectroscopy (XPS). Scanning Tunneling Microscopy (STM) used to characterize and covalent networks identify the temperature regimes for bond formation.

Adsorption of the brominated aromatic molecule 1,3,5-tris(4-bromophenyl)benzene on different metallic substrates, namely Cu(111), Ag(111), and Ag(110), has been studied by variable-temperature scanning tunneling microscopy (STM). Depending substrate temperature, material, crystallographic orientation, a surface-catalyzed dehalogenation reaction is observed. Deposition onto catalytically more active substrates Cu(111) Ag(110) held at room temperature leads to cleavage carbon−bromine bonds...

‘Covalent self-assembly’, i.e. the on-surface synthesis of covalent organic aggregates and networks, has received considerable attention. This review covers recent scanning tunnelling microscopy (STM) based studies on intermolecular reactions carried out solid substrates that resulted in surface-confined covalently interlinked nanostructures. Experiments showed their defect density crucially depends targeted dimensionality: while zero-dimensional one-dimensional chains ribbons can be...

Surface-assisted Ullmann coupling is the workhorse of on-surface synthesis. Despite its obvious relevance, many fundamental and mechanistic aspects remain elusive. To shed light on individual reaction steps their progression with temperature, temperature-programmed X-ray photoelectron spectroscopy (TP-XPS) experiments are performed for a prototypical model system. The activation by initial dehalogenation tracked monitoring Br 3d core levels, whereas C 1s signature used to follow emergence...

Abstract We demonstrate here that supramolecular interactions enhance the sensitivity towards detection of electron‐deficient nitro‐aromatic compounds (NACs) over discrete analogues. NACs are most commonly used explosive ingredients and common constituents many unexploded landmines during World War II. In this study, we have synthesised a series pyrene‐based polycarboxylic acids along with their corresponding esters. Due to electron richness fluorescent behaviour pyrene moiety, all act as...

The polymerization of 1,4-diethynylbenzene was studied on a Cu(111) surface using scanning tunneling microscopy (STM) under ultra-high vacuum conditions. Thermal activation yielded disordered covalent networks, where distinct basic structural motifs indicate different coupling reactions.

The driving force for self-assembly is the associated gain in free energy with decisive contributions from both enthalpy and entropy differences between final initial state. For monolayer at liquid-solid interface, solute molecules are initially dissolved liquid phase then become incorporated into an adsorbed monolayer. In this work, we present adapted Born-Haber cycle obtaining precise values a key ingredient profound thermodynamic understanding of process. By choosing terephthalic acid as...

Scanning tunneling microscopy is used to characterize and nanopattern a covalent organic framework incorporating C₆₀-fullerene in its pores.

Two-dimensional (2D) polymers are novel covalent sheet materials with promising properties, but also great synthetic challenges. The inadequacy of traditional wet chemical synthesis calls for new paradigms. In this respect, employing surfaces as inherently 2D reaction venues appears an adequate choice and has recently already yielded encouraging results. Polymerization at air − liquid interfaces been reported from time to over the last decades, whereas recent efforts on solid less...

We compare the self-assembly of various isomers benzene−dicarboxylic acids at interface between solution and graphite substrate. In case planar it was possible to observe long-range ordered monolayers by STM. However, no adsorption observed for nonplanar 1,2-benzene−dicarboxylic acid. By means a control experiment with 1,2,4,5-benzene-tetracarboxylic acid, demonstrate that structure is not decisive reason absence self-assembly. fact, direct neighborhood two carboxylic groups in acid does...