SKM 2023 – scientific programme

Parts | Days | Selection | Search | Updates | Downloads | Help

O: Fachverband Oberflächenphysik

O 10: Organic Molecules on Inorganic Substrates II: Electronic, Optical and Other Properties II

O 10.5: Talk

Monday, March 27, 2023, 16:15–16:30, CHE 89

Nickel(II) Porphyrins versus Nickel(II) Corroles on Different Metal Surfaces: Oxidation-State Tuning of Nickel Tetrapyrrole Complexes — •Jan Herritsch¹, Jan-Niclas Luy^1,2, Ralf Tonner-Zech^1,2, and J. Michael Gottfried¹ — ¹Fachbereich Chemie, Philipps-Universität Marburg, Germany — ²Wilhelm-Ostwald-Institut, Leipzig, Germany

Using the example of Ni tetrapyrrole complexes, we demonstrate how the oxidation state of the central atom and the molecule-substrate interaction can be influenced by a modification of the ligand. In particular, the effect of the ring size is addressed by comparing porphyrins with corroles. The latter represent a smaller macrocycle and provide a tighter coordination environment for the metal center. In addition, Ni(II) corroles have an unusual electronic structure with an unpaired electron located at the π-electron system of the ligand. Here, we focus on the interactions of Ni(II) porphyrins and corroles with different metal surfaces (Au(111), Ag(111), Cu(111)). Depending on the used substrate, the Ni(II) porphyrin is subject to an interfacial charge transfer resulting in the reduction of the Ni atom as was shown by XPS. However, due to its unique properties Ni(II) corroles exhibit a different behavior at the metal/organic interface. While the corrole's Ni(II) state remains unchanged even on the reactive Cu(111) surface, the ligand is subject to a charge transfer by accepting electron density from the substrate. This charge transfer could be traced with experimental valence spectra (UPS), which were evaluated with the help of quantum chemical calculations (DFT).