Conformational adaptation and manipulation of manganese tetra(4-pyridyl)porphyrin molecules on Cu(111)

Abstract

Porphyrins are highly flexible molecules and well known to adapt to their local environment via conformational changes. We studied the self-assembly of manganese meso-tetra(4-pyridyl)porphyrin (Mn-TPyP) molecules on a Cu(111) surface by low temperature scanning tunneling microscopy (STM) and atomic force microscopy (ATM). We observe molecular chains along the 110 direction of the substrate. Within these chains, we identify two molecular conformations, which differ by the orientation of the upward bending of the macrocycle. Using density functional theory, we show that this saddle shape is a consequence of the rotation and inclination of the pyridyl groups towards Cu adatoms, which stabilize the metal-organic chains. The molecular conformations obey a strict alternation, reflecting the mutual enforcement of conformational adaptation in densely packed structures. Tunneling electrons from the STM tip can induce changes in the orientation of the pyridyl endgroups. The switching behaviour varies with the different adsorption configurations.

Fine-tuning of two-dimensional metal–organic nanostructures via alkali–pyridyl coordination

“…20,21 The alternative rotation of the molecular units can be ascribed to the steric repulsive force between the peripheral H atoms of the four py terminals which are linked at a single Na center. 37,38 To reveal the nature of the Na-py interaction, we have conducted XPS experiments, and examined Na 2p and N 1s spectra. In the top panel of Fig.…”

Structure, Properties, and Reactivity of Porphyrins on Surfaces and Nanostructures with Periodic DFT Calculations

“…The dihedral angle of the pyridyl rings is found to be 70 • with adlayer structure primarily directed by lateral intermolecular interactions. Another PDFT study of MnTPyP on Cu(111) [73] with GGA-PBE [45] showed that MnTPyP adsorbs in a saddle shape due to the rotation and inclination of the pyridyl groups towards Cu adatoms, which stabilize the metal-organic chains. Metalated and non-metalated meso-substituted phenyl porphyrins are some of the extensively studied porphyrins on surfaces [71].…”

Rasterkraftmikroskopie für die molekulare Strukturaufklärung

“…Beim AFM dient die Hçhe der Messspitze z*, an der die negative Frequenzverschiebung füre ine bestimmte laterale Position der Spitze am grçßten ist, als Maß fürd ie Adsorptionshçhe. [33,[70][71][72] Darüber hinaus kçnnen auch Metallatome in metallorganischen Komplexen beobachtet und lokalisiert werden. [49] Chemisorption von Molekülen kann von Physisorption unterschieden werden.…”

“…[69] Molekulare Konformationen kçnnen präzise voneinander unterschieden und aufgelçst werden. [33,[70][71][72] Darüber hinaus kçnnen auch Metallatome in metallorganischen Komplexen beobachtet und lokalisiert werden. [73][74][75] Die Adsorptionsgeometrie von Pentacen auf Cu(111) ist in Abbildung 2als Karte der Messspitzenhçhe z*dargestellt, welche aus einer 3D-Kraftkarte extrahiert wurde.…”