H-bonding supramolecular assemblies of PTCDI molecules on the Au (111) surface (original) (raw)
Related papers
Experimental and theoretical analysis of H-bonded supramolecular assemblies of PTCDA molecules
2010
Using a systematic method based on considering all possible hydrogen bond connections between molecules and subsequent density-functional theory ͑DFT͒ calculations, we investigated planar superstructures that the perylene-3,4,9,10-tetracarboxylic-3,4,9,10-dianhydride ͑PTCDA͒ molecules can form in one and two dimensions. Structures studied are mostly based on two molecule unit cells and all assemble in flat periodic arrays. We show that 42 different monolayer structures are possible, which can be split into eight families of distinct structures. A single representative of every family was selected and relaxed using DFT. We find square, herringbone and brick wall phases ͑among others͒ which were already observed on various substrates. Using scanning tunneling microscopy in ultrahigh vacuum, we also observed herringbone and square phases after sublimation of PTCDA molecules on the Au͑111͒ surface at room temperature, the square phase being observed for the first time on this substrate. The square phase appears as a thin stripe separating two herringbone domains and provides a perfect structural matching for them. A similar structural formation serving as a domain wall between two other phases has been recently reported on the same surface formed by melamine molecules ͓F. Silly et al., J. Phys. Chem. C 112, 11476 ͑2008͔͒. Our theoretical analysis helps to account for these and other observed complex structures.
Metalorganic extended 2D structures: Fe-PTCDA on Au(111
Nanotechnology, 2010
In this work we combine organic molecules of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) with iron atoms on an Au (111) substrate in ultra-high vacuum conditions at different temperatures. By means of scanning tunnelling microscopy (STM) we study the formation of stable 2D metal-organic structures. We show that at certain growth conditions (temperature, time and coverage) stable 'ladder-like' nanostructures are obtained. These are the result of connecting together two metal-organic chains through PTCDA molecules placed perpendicularly, as rungs of a ladder. These structures, stable up to 450 K, can be extended in a 2D layer covering the entire surface and presenting different rotation domains. STM images at both polarities show a contrast reversal between the two molecules at the unit cell. By means of density functional theory (DFT) calculations, we confirm the stability of these structures and that their molecular orbitals are placed separately at the different molecules.
Nano Research, 2012
Supramolecular self-assembly of the organic semiconductor perylene-3,4,9,10-tetracarboxylic diimide (PTCDI) together with Ni atoms on the inert Au(111) surface has been investigated using high-resolution scanning tunneling microscopy under ultrahigh vacuum conditions. We demonstrate that it is possible by tuning the co-adsorption conditions to synthesize three distinct self-assembled Ni-PTCDI nanostructures from zero-dimensional (0-D) nanodots over one-dimensional (1-D) chains to a two-dimensional (2-D) porous network. The subtle interplay among non-covalent interactions responsible for the formation of the observed structures has been revealed from force-field structural modeling and calculations of partial charges, bond orders and binding energies in the structures. A unifying motif for the 1-D chains and the 2-D network is found to be double N-HO hydrogen bonds between PTCDI molecules, similar to the situation found in surface structures formed from pure PTCDI. Most interestingly, we find that the role of the Ni atoms in forming the observed structures is not to participate in metal-organic coordination bonding. Rather, the Ni adatoms acquire a negative partial charge through interaction with the substrate and the Ni-PTCDI interaction is entirely electrostatic.
The Journal of Physical Chemistry B, 2004
The adsorption and ordering of the molecule terephthalic acid (TPA), 1,4-benzene-dicarboxylic acid C 6 H 4 -(COOH) 2 , on the reconstructed Au(111) surface has been studied in situ in ultrahigh vacuum by scanning tunneling microscopy (STM) at room temperature. Two-dimensional (2D) self-assembled supramolecular domains evolve, wherein the well-known one-dimensional (1D) carboxyl H-bond pairing scheme is identified. Since the individual molecules occupy a distinct adsorption site and the supramolecular ordering usually extends over several substrate reconstruction domains, a significant variation in hydrogen bond lengths is encountered, which illustrates the versatility of hydrogen bridges in molecular engineering at surfaces. Ab initio calculations for a 1D H-bonded molecular chain provide insight into the limited geometric response of the molecules in different local environments.
Langmuir : the ACS journal of surfaces and colloids, 2018
We combine ambient (air) and ultrahigh vacuum (UHV) scanning tunneling microscopy (STM) and spectroscopy (STS) investigations together with density functional theory (DFT) calculations to gain a subnanometer insight into the structure and dynamic of two-dimensional (2D) surface-supported molecular networks. The planar tetraferrocene-porphyrin molecules employed in this study undergo spontaneous self-assembly via the formation of hydrogen bonded networks at the gold substrate-solution interface. To mimic liquid phase ambient deposition conditions, film formation was accomplished in UHV by electro-spraying a solution of the molecule in chloroform onto an Au(111) substrate, thereby providing access to the full spectroscopic capabilities of STM that can be hardly attained under ambient conditions. We show that molecular assembly on Au (111) is identical in films prepared under the two different conditions, and in good agreement with the theoretical predictions. However, we observe the c...
In this paper, we use atomic force microscopy (AFM) to nanostructure and image 1,10-decanedithiol (DDT) and biphenyl 4,4′-dithiol (BPDT) layers on Au(111) surfaces comparing them to those prepared by self-assembly. First, layers of dithiols are self-assembled from solution onto gold surfaces and are imaged in situ with an AFM to examine the roughness of the layers. Second, 100 nm × 100 nm monolayer patches made of dithiol molecules are nanografted into a self-assembled monolayer (SAM) inert matrix made of 1-decanethiol (DT). Although nanografting of thiols routinely generates very compact layers with good height uniformity, nanostructuring of dithiols using this method always yields multilayers that form through intermolecular S-S bonds. We demonstrate in this paper two possible ways of tailoring, layer by layer, the structure of dithiols. First, we form multilayers by nanografting, using then the AFM tip to gradually shave away the top layers. In the second way, we add antioxidant to the solution while doing nanografting to suppress the oxidative coupling of the-SH groups. We found that nanografting in the presence of excess amounts of antioxidant can produce monolayers of dithiols. The so-produced DDT monolayer patches are lower than what can be calculated by the 30° tilt model, while the height of nanografted patches of BPDT closely corresponds to a vertical configuration. Finally, we use conductive-probe AFM to investigate the electron tunneling properties through BPDT multilayers. The molecules in these layers turn out to behave as conductive molecular wires and making these nanostructures good candidates for constructing molecular electronic devices.
Structural phase transition in self-assembled 1,10′ phenanthroline monolayer on Au(111)
Surface Science, 1997
The self-assembly of 1,10' phenanthroline (phen) on Au(lll) from aqueous solutions has been studied as a function of the substrate potential with in situ scanning tunneling microscopy (STM). The phen molecules adsorb spontaneously onto the substrate with a preference to decorate the reconstruction stripes of Au(111). The adsorbed molecules stand vertically with their nitrogen atoms facing the Au(111) and stack, like rolls of coins, into polymer-like chains. At high potentials, the chains pack closely in parallel and form an ordered monolayer. Decreasing the potential to a critical value, the chains become randomly oriented via a reversible order-disorder phase transition that resembles the nematicisotropic transition in liquid crystal materials. High resolution images reveal each phen molecule as two blobs located at the two nitrogen atoms, indicating that the coupling between the nitrogen atoms and Au is responsible for the tunneling current probed by STM The phen monolayer contains pits with a depth of about one Au layer, which may be attributed to surface stress induced by the strong adsorption of the phen molecules on the surface. © 1997 Elsevier Science B.V.