| 1. |
- Brede, Jens, et al.
(författare)
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Adsorption and conformation of porphyrins on metallic surfaces
- 2009
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Ingår i: JOURNAL OF VACUUM SCIENCE and TECHNOLOGY B. - : American Vacuum Society. - 1071-1023. ; 27:2, s. 799-804
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Tidskriftsartikel (refereegranskat)abstract
- Tetraphenyl porphyrins (TPP) belong to a highly interesting class of molecules with a large variety of electronic, magnetic, and structural properties. So far, local investigations by scanning probe techniques were primarily focused on larger agglomerates of TPP molecules. Here, experimental results of the observation and manipulation of isolated molecules adsorbed on cold metal substrates by means of low temperature scanning tunneling microscopy are presented. Depending on the surface geometry, i.e., Cu(111) VS, Cu(100) three distinct deformations of the molecular structure are identified reflecting the interaction of the phenyl periphery with the substrate. In a second step, controlled manipulation in terms of deformation of the porphyrin core, ligand dissociation, and lateral displacement of the phenyl periphery are demonstrated.
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| 2. |
- Brede, Jens, et al.
(författare)
-
Dynamics of molecular self-ordering in tetraphenyl porphyrin monolayers on metallic substrates
- 2009
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Ingår i: NANOTECHNOLOGY. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 20:27, s. 275602-
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Tidskriftsartikel (refereegranskat)abstract
- A molecular model system of tetraphenyl porphyrins (TPP) adsorbed on metallic substrates is systematically investigated within a joint scanning tunnelling microscopy/molecular modelling approach. The molecular conformation of TPP molecules, their adsorption on a gold surface and the growth of highly ordered TPP islands are modelled with a combination of density functional theory and dynamic force field methods. The results indicate a subtle interplay between different contributions. The molecule-substrate interaction causes a bending of the porphyrin core which also determines the relative orientations of phenyl legs attached to the core. A major consequence of this is a characteristic (and energetically most favourable) arrangement of molecules within self-assembled molecular clusters; the phenyl legs of adjacent molecules are not aligned parallel to each other (often denoted as pi-pi stacking) but perpendicularly in a T-shaped arrangement. The results of the simulations are fully consistent with the scanning tunnelling microscopy observations, in terms of the symmetries of individual molecules, orientation and relative alignment of molecules in the self-assembled clusters.
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