Self-assembly and conformation of tetrapyridyl-porphyrin molecules on Ag(111)

Abstract

We present a low-temperature scanning tunneling microscopy (STM) study on the supramolecular ordering of tetrapyridyl-porphyrin (TPyP) molecules on Ag(111). Vapor deposition in a wide substrate temperature range reveals that TPyP molecules easily diffuse and self-assemble into large, highly ordered chiral domains. We identify two mirror-symmetric unit cells, each containing two differently oriented molecules. From an analysis of the respective arrangement it is concluded that lateral intermolecular interactions control the packing of the layer, while its orientation is induced by the coupling to the substrate. This finding is corroborated by molecular mechanics calculations. High-resolution STM images recorded at 15 K allow a direct identification of intramolecular features. This makes it possible to determine the molecular conformation of TPyP on Ag(111). The pyridyl groups are alternately rotated out of the porphyrin plane by an angle of 60 degrees.

Chiral Kagomé Lattice from Simple Ditopic Molecular Bricks

“…Therefore, our model suggests that one driving force for the different organic architectures is the interplay between intermolecular interactions and the epitaxial fit to the Ag atomic lattice. 8,18 In the STM images (cf. Figure 2a,c), the observed highly regular pattern of different brightness supports our model and thus the arguments of the commensurate networks.…”

Communication: Substrate induced dehydrogenation: Transformation of octa-ethyl-porphyrin into tetra-benzo-porphyrin

“…1 Recently, it was shown that the Cu(111) surface can produce almost perfect layers of graphene by the dehydrogenation of hydrocarbon precursor molecules. 2,3 Scanning tunneling microscopy 4 (STM) is a powerful tool to study the adsorption geometry of different molecules on a conducting surface, 5,6 diffusion processes of single molecules 7 or atoms 8 and even to manipulate single molecules with the STM tip. 9,10 Porphyrins and phthalocyanines are the most studied organic molecules in the monolayer and submonolayer regime.…”

Self-Assembly of Nanoporous Chiral Networks with Varying Symmetry from Sexiphenyl-dicarbonitrile on Ag(111)

“…The observed structures do not show a Moiré pattern for all tunneling conditions we tested; therefore, commensurate models have been constructed. For comparison, the noncommensurate supercell of tetrapyridyl-porphyrin on Ag(111) resulted in an evident modulation of the apparent height of the molecules independent of bias voltage, 50 whereas the apparent height of our molecules is identical for adjacent unit cells.…”