1,3,5-Benzenetribenzoic Acid on Cu(111) and Graphene/Cu(111): A Comparative STM Study

Abstract

The self-assembly of 1,3,5-benzenetribenzoic acid (BTB) molecules on both Cu(111) and epitaxial graphene grown on Cu(111) were studied by scanning tunneling microscopy (STM) and low-energy electron diffraction (LEED) under ultrahigh vacuum conditions. On Cu(111), the BTB molecules were found to mainly arrange in close-packed structures through H-bonding between the (partially) deprotonated carboxylic acid groups. In addition, porous structures formed by intact BTB molecules-and also based on H-bonding-were observed. On graphene grown on Cu(111) the BTB molecules mainly form porous structures accompanied by small patches of disordered close-packed structures. Upon annealing, BTB adsorbed on Cu(111) is fully deprotonated and arranges in the close-packed structure while in contrast on graphene/Cu(111) the porous network is exclusively formed. This shows that the molecular self-assembly behavior is highly dependent on the first substrate layer: one graphene layer is sufficient to considerably alter the interplay of molecule substrate and intermolecular interactions in favor of the latter interactions.

Imaging the Solvation of a One‐Dimensional Solid on the Molecular Scale

“…[14,15] Here,weused this technique to follow the solvation of ah ydrogen-bonded solid in real space.T he hydrogenbond-assisted formation of supramolecular networks on surfaces has been thoroughly investigated by scanning probe microscopic techniques in recent years. [16][17][18][19][20][21] These networks may be understood as low-dimensional crystals,which makes them excellent test subjects for the investigation of solvation processes by STM. To maximize accessibility for water, we synthesized amolecule that is able to form hydrogen-bonded one-dimensional chains.For this purpose,3-methoxy-9-diazofluorene (MDAF) was chosen, which consists of af luorene backbone that is functionalized with two polar groups,namely am ethoxy group of intermediate polarity and ah ighly polar diazo group.W ec hose Ag(111) as as ubstrate because of its low reactivity towards adsorbates at low temperatures according to d-band theory.…”

When 2D Materials Meet Molecules: Opportunities and Challenges of Hybrid Organic/Inorganic van der Waals Heterostructures

“…Several groups have studied the process of molecular self‐assembly on graphene in the real space by scanning tunneling microscopy . These studies often focused epitaxial graphene grown onto metallic or semiconducting SiC surfaces, and recently also on graphene transferred onto insulating SiO 2 or BN …”

“…While in several cases the molecular assembly and its properties represent the main focus of STM studies, only a few reports address the effects of a given molecular assembly on the electronic properties of 2DMs . In these cases, an STM study of the molecular assembly on a 2DM (typically graphene) is combined to the investigation of the electrical properties of the same system, addressed at the macroscopic level (for instance, in devices).…”

“…The interactions of molecular layers with the inert surface of 2DM are mediated by vdW forces analogous to those between different inorganic sheets, so that similar interface effects can be envisaged in both cases, making organic/inorganic architectures the hybrid equivalent of fully inorganic vdWHs. The analogy is even more profound if one considers that crystalline molecular monolayers can be obtained on 2DMs that can be integrated in complex multilayered heterostructures composed of alternating organic/inorganic single layers.…”

Comparing the Self‐Assembly of Sexiphenyl‐Dicarbonitrile on Graphite and Graphene on Cu(111)

“…[7][8][9] On substrates where the interaction of graphenew ith the underlying metal substratei sw eak, e.g., Pt(111), SiC, or Cu(111), the self-assembly was mainly governed by intermolecularinteractions. [10][11][12][13][14] Herein, we report the self-assembly of sexiphenyl-dicarbonitrile (NC-Ph 6 -CN, Scheme 1) on highlyo riented pyrolytic graphite (HOPG)a nd single-layer graphene on Cu(111). We studied the structurala nd electronic properties of the molecules using scanningt unneling microscopy (STM), scanning tunneling spectroscopy (STS), and low-energy electron diffraction (LEED).…”