Dr. Letizia Savio

CNR-IMEM, Italy
Letizia Savio is a senior researcher on the Institute of Materials for Electronic and Magnetism of CNR. Her research interests are centred on the investigation of molecule-surface interactions at the nanoscopic level by spectroscopic (HREELS and XPS) and microscopic (STM) means. In particular, she has focussed her attention on the study of the hybrid organic-inorganic interface, on self-assembly phenomena at metal surfaces and 2D layers and on supported low-dimensional carbon-based systems.

Talk title: Pd-cyclometallated complexes at Ag(110): from self-assembly to the synthesis of new compounds
Among possible organometallic compounds, complexes of the Group 10 elements are attractive due to their widespread use in numerous applications such as catalytic synthetic processes, biological chemistry and material science. In particular, many palladium complexes have been extensively studied as catalysts in several cross-coupling reactions. Their coupling to a metal surface is interesting, since it could lead to a major impact in catalysis and sensoristic, but research in this field is still limited.

Cyclometallated complexes are good candidates for this kind of studies since they are thermally stable and can be sublimed in vacuum conditions. However, only few studies have been reported in literature [1,2], mainly concerned to the use of Ir(III)- and Pt(II)-containing molecules of interest as light emitters.

Based on our previous experience on surface-assisted polymerization of aromatic hydrocarbons [3,4], we deposited Pd cyclometallated compounds - relevant especially for catalytic applications [5,6] - on Ag(110). Their self-assembly at the surface may lead to the formation of a C-based layer with Pd atoms acting as active centers in well-defined positions. The deposition and the thermal evolution of these complexes was followed by scanning tunnelling microscopy and X-ray photoemission spectroscopy, while the initial and final configurations are validated by ab-initio calculations.

However, Pd-cyclometallates reveal a surface chemistry much more complex than expected. Different self-assembled geometries are observed depending on experimental conditions, but in all cases the molecules dissociates, Pd atoms diffuse below the Ag surface and new compounds can form via cross coupling between the two organic fragments.

In my talk I will present our recent results on this system and a preliminary comparison with similar experiments performed on HOPG, on which molecular dissociation does not occur.

[1] S. Wilde et al., ACS Appl. Mater. Interfaces. 10 (2018) 22460.
[2] J. Ren et al., Angew. Chemie - Int. Ed. 58 (2019) 15396.
[3] M. Smerieri et al., Nanoscale 8 (2016) 17843.
[4] M. Smerieri et al., Phys.Chem.Chem.Phys. 20 (2018) 26161.
[5] M. Stojkovska et al., Appl. Surf. Sci. 606 (2022) 154960.
[6] J.E. Barcelon et al., Appl. Surf. Sci. 609 (2023) 155307.