Layer-selective epitaxial self-assembly of porphyrins on ultrathin insulators

Ramoino, Luca; Arx, Matthias von; Schintke, Silvia; Baratoff, A.; Güntherodt, H.-J.; Jung, Thomas A.

doi:10.1016/j.cplett.2005.10.006

Cited by 64 publications

(66 citation statements)

References 31 publications

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“…In contrast to previous findings on porphyrins deposited on NaCl/Cu(1 1 1) [12], molecules are also adsorbed on 3 ML NaCl islands and form the same bimolecular structure as on the metal and on 2 ML NaCl islands. Their adsorption energy, however, must be lower than on 2 ML NaCl, as evidenced by the increased difficulty of scanning such regions, where molecules are frequently displaced due to tip-molecule interactions.…”

Section: Bimolecular Ribbons On Nacl/au(11 12 12)contrasting

confidence: 53%

“…Growth and characterization of two-dimensional ordered supramolecular structures on ultrathin NaCl films has only been achieved in very few studies [11][12][13], which is due to experimental difficulties related to the low molecular adsorption energy on such insulating layers. All three mentioned studies were performed on NaCl islands having similar morphological characteristics as the ones observed here on Au(1 1 1).…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, it has been shown that, upon adsorption of molecules on ultrathin NaCl films on metal surfaces, inherent electronic and optical properties of individual molecules can be studied [8][9][10]. However, to our knowledge, there are only three published STM studies on the growth of two-dimensional molecular islands on insulating NaCl layers, two of them on metal-containing porphyrine molecules [11,12], and the third one on C 60 molecules [13]. The small number of investigations about adsorbates on NaCl layers is at least partly due to weak molecule-substrate interactions, which make the stabilization and STM imaging of such systems a challenging task.…”

Section: Introductionmentioning

confidence: 96%

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Stabilization of bimolecular islands on ultrathin NaCl films by a vicinal substrate

et al. 2009

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a b s t r a c tThe structure of ultrathin NaCl films on Au(1 1 1) and on Au(11 12 12), as well as the one of bimolecular 3,4,9,10-perylenetetracarboxylic diimide (PTCDI) and 1,4-bis-(2,4-diamino-1,3,5,-triazine)-benzene (BDATB) islands on NaCl films on both surfaces have been studied with a low-temperature scanning tunnelling microscope. We show that intermixed bimolecular assemblies based on selective three-fold hydrogen-bonding (H-bonding), that have previously been observed on Au(1 1 1) and on Au(11 12 12), can also be stabilized on insulating NaCl films on Au, however, only if these films are grown on Au(11 12 12) and not on Au(1 1 1). The behaviour of the heterocomplex structures is found to be largely influenced by the structural properties of the underlying substrate and by the number of NaCl layers. On a partly NaCl-covered Au(1 1 1) surface, the excess of molecules after completion of the first layer on Au prefers to form a second molecular layer based on ordered heterocomplex structures rather than to adsorb on the NaCl islands. The use of a vicinal surface together with the strong cohesion characteristic of the NaCl film introduces smooth elastic deformations on the NaCl(0 0 1) plane. As a consequence, the periodically modified structure of the overlayer provides preferential binding sites and allows adsorption of two-dimensional molecular structures. In contrast to what is observed on Au(11 12 12), the molecular domains on the NaCl film do not follow the Au step directions, but the NaCl(0 0 1) high symmetry directions. Our results provide a strategy to increase the adsorption energy of flat molecules on insulating layers by choosing a vicinal metal substrate.

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Section: Bimolecular Ribbons On Nacl/au(11 12 12)contrasting

confidence: 53%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

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Stabilization of bimolecular islands on ultrathin NaCl films by a vicinal substrate

et al. 2009

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“…At the interface between the two organic layers, the expected weaker chemical interactions permit better understanding of the molecular band offsets, in spite of usually limited understanding of the in-terface structure. This weak interaction between the metal phthalocyanines and an organic polymer substrate should, in fact, be weaker than the interactions observed at insulating substrate, where the latter interactions are seen to be less strong than for a conducting substrate [10].…”

Section: Introductionmentioning

confidence: 99%

Different approaches to adjusting band offsets at intermolecular interfaces

Dowben

Xiao

et al. 2008

Applied Surface Science

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“…An intriguing demonstration of this effect is the self-assembly of porphyrins, which are decoupled from their metal substrate by insulating NaCl layers of varying thickness. 23 The interaction was shown to be dependent on the NaCl layers, and the thicker the NaCl the weaker the interaction and the more delayed the onset of network formation. The occupation of the center ring of the porphyrin may affect the molecular adsorption at surfaces.…”

mentioning

confidence: 99%

Self-Assembly and Properties of Nonmetalated Tetraphenyl-Porphyrin on Metal Substrates

et al. 2010

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IntroductionThe self-assembly of porphyrins on well-defined surfaces is attracting considerable interest because it promises to create surface patterns with nanometer dimension that exhibit specific electronic, sensoric, optic, or catalytic functionality 1-3 or even interesting magnetic properties. 4,5 The ability of porphyrin to show self-organization and to accommodate metal atoms in their macrocycle is exploited, for instance, to form metal−organic frameworks or adsorbed layers for catalysis. [6][7][8][9] The selfassembly is mainly driven by noncovalent metal−organic coordination interactions, which is well-known and important in solution-based 3D supramolecular chemistry. [10][11][12][13][14][15] Porphyrin molecules have been adsorbed onto surfaces to form supramolecular networks from solution, [16][17][18][19] electrochemically 20,21 or by thermal evaporation under vacuum conditions. [22][23][24][25][26][27][28] While there is a rich literature on the electronic structure of these adsorbates, the surface adlayer structures have also been characterized with scanning force microscopy, scanning tunneling microscopy, or X-ray absorption near-edge structure analysis. 29 The rationale of such experiments on 2D structures has been to study the long-range interactions that determine the self-assembly processes. It has been demonstrated that the bottom-up fabrication of highly organized porphyrin layers, as well as of porphyrin-based multicomponent molecular entities, depends on the interplay of molecule−molecule and substrate−molecule interactions. Molecule−substrate interactions will set limits to the mobility of the adsorbed molecules and may alter the electronic structure of the absorbed molecules, or the electronic states at the surfaces may become locally perturbed by the adsorbate. 60 A consequence is that the established concepts of solution-based coordination chemistry cannot be applied without appropriate modification. The substrate thus becomes an additional parameter to control the adsorption energy of the molecules and, hence, their diffusivity at surfaces. An intriguing demonstration of this effect is the self-assembly of porphyrins, which are decoupled from their metal substrate by insulating NaCl layers of varying thickness. 23 The interaction was shown to be dependent on the NaCl layers, and the thicker the NaCl the weaker the interaction and the more delayed the onset of network formation. The occupation of the center ring of the porphyrin may affect the molecular adsorption at surfaces. As an example, free-base or Cu-incorporated porphyrin molecules show different arrangements along step edges on Cu(100) surfaces. While 2H-TBPP bridges over the step edges, Cu-TBPP sits on either side of step edges. 27 In contrast, no difference in the network architecture was found for differently metalated TPP on Ag(111). 57 Such a subtle dependence of adsorption site on metal incorporation, if fully understood, may become useful to control the self-assembly or the properties of the molecules on surfaces.The goal...

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Layer-selective epitaxial self-assembly of porphyrins on ultrathin insulators

Cited by 64 publications

References 31 publications

Stabilization of bimolecular islands on ultrathin NaCl films by a vicinal substrate

Stabilization of bimolecular islands on ultrathin NaCl films by a vicinal substrate

Different approaches to adjusting band offsets at intermolecular interfaces

Self-Assembly and Properties of Nonmetalated Tetraphenyl-Porphyrin on Metal Substrates

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