Book/Dissertation / PhD Thesis

FZJ-2023-00823

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Activating molecular magnetism by controlled on-surface coordination

Cojocariu, I. (Corresponding author)FZJ*

2022
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich
ISBN: 978-3-95806-674-8

Please use a persistent id in citations: http://hdl.handle.net/2128/33728

Abstract: The enduring interest in the study of metallorganic complexes emerges from the demonstrated multi-faced applications, which range from gas sensing to memory storage, and heterogeneous catalysis, as well as single-molecule magnets. The fundamental properties required for the molecule to achieve these functions can already be intrinsically present in the molecule itself, or its functionalization can be exploited to meet the desired requirements. In this regard, on-surface molecular functionalization serves as a mechanism to stabilize the chelated metal ions in catalytically and magnetically active states. The importance of the present thesis results from the investigation of the factors guiding magnetism and catalytic activity at the organic-metal interface, where the organic molecule is chosen to be a transition metal porphyrin or phthalocyanine.The first well-known factor influencing the properties of the overlayer is the surface. The cruciality of the substrate choice will be demonstrated by combining different embedded transition metal ions, characterized by a different electronic configuration, and several metal surfaces,i.e. gold, silver, and copper, possessing an increasing surface reactivity. By exposing various interfaces to an external ligand, nitrogen dioxide, it is demonstrated that only the interface formed with copper retains the necessary properties for further manipulating electronic andmagnetic properties of the metal core through axial ligand interaction. Another important factor identified in the view of organic interface functionalization is the modification of molecular periphery and structure. An example of this is the introduction of strongly electron withdrawing groups in the metal phthalocyanine, and the possibility of realizing well-defined heterostacked p-n junctions is demonstrated. A distinct established approach for structural modification is found in molecular planarization induced by an on-surface temperature-induced cyclodehydrogenation reaction. This transformation allows us to define the indispensability of molecular flexibility for employing these interfaces as NO2 sensors. However, in the case of metal phthalocyanines, which are planar in their pristine form, it is shown that although there is no interaction with the undissociateddioxide, the molecule-substrate interface is active in NO2 cleavage and the stabilization of different magnetic states is still achievable.

Note: Dissertation, Uni Duisburg-Essen, 2022

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Contributing Institute(s):

1. Elektronische Eigenschaften (PGI-6)

Research Program(s):

1. 5211 - Topological Matter (POF4-521) (POF4-521)

Appears in the scientific report 2022

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