Iron phthalocyanine on Cu(111): Coverage-dependent assembly and symmetry breaking, temperature-induced homocoupling, and modification of the adsorbate-surface interaction by annealing

Abstract

We have examined the geometric and electronic structures of iron phthalocyanine assemblies on a Cu(111) surface at different sub- to mono-layer coverages and the changes induced by thermal annealing at temperatures between 250 and 320 °C by scanning tunneling microscopy, x-ray photoelectron spectroscopy, and x-ray absorption spectroscopy. The symmetry breaking observed in scanning tunneling microscopy images is found to be coverage dependent and to persist upon annealing. Further, we find that annealing to temperatures between 300 and 320 °C leads to both desorption of iron phthalocyanine molecules from the surface and their agglomeration. We see clear evidence of temperature-induced homocoupling reactions of the iron phthalocyanine molecules following dehydrogenation of their isoindole rings, similar to what has been observed for related tetrapyrroles on transition metal surfaces. Finally, spectroscopy indicates a modified substrate-adsorbate interaction upon annealing with a shortened bond distance. This finding could potentially explain a changed reactivity of Cu-supported iron phthalocyanine in comparison to that of the pristine compound.

On‐Surface Metalation and 2D Self‐Assembly of Pyrphyrin Molecules Into Metal‐Coordinated Networks on Cu(111)

“…The molecules appear then with slightly irregular shapes and regular self‐assembly is absent. A similar appearance was also observed for tetrapyrrole monolayers on Cu and Ag substrates which also dehydrogenated at the periphery by annealing to 500 – 640 K …”

“…Such pyrolysis is a common feature for adsorbed hydrocarbons that are too tightly bound to the surface to become desorbed intact. This process has also been observed for monolayers of tetrapyrroles adsorbed on metal surfaces …”

Extended iron phthalocyanine islands self-assembled on a Ge(001):H surface

“…Moreover, they are ideal candidates to study the influence of the interaction between the central metal atom and the surrounding ligands on the overall properties. Commonly, metal phthalocyanines and their derivatives have been investigated on crystalline metal surfaces [43][44][45][46][47][48][49][50][51][52][53][54][55][56][57]. However, the need to electronically decouple organic moieties from the underlying substrates directed the attention towards insulators and/or semiconductors.…”

Interaction Channels Between Perfluorinated Iron Phthalocyanine and Cu(111)

“…Due to its flexibility in the spin ground state, iron complexes might be of particular interest in the view of electronic properties . Compared to other metal substrates, less attention was paid to iron phtalocyanines on copper substrates . For FePc on Cu(111), a charge transfer from the substrate to the molecule was reported …”

“…Compared to other metal substrates, less attention was paid to iron phtalocyanines on copper substrates . For FePc on Cu(111), a charge transfer from the substrate to the molecule was reported …”