%0 Thesis
%A Baranowski, Daniel
%T Probing the Transformation from Transition Metal Complexes to Extended Two-Dimensional Nanostructures
%V 284
%I Duisburg-Essen
%V Dissertation
%C Jülich
%M FZJ-2024-06132
%@ 978-3-95806-772-1
%B Reihe Schlüsseltechnologien / Key Technologies
%P XII, 103
%D 2024
%Z Dissertation, Duisburg-Essen, 2024
%X The controlled on-surface stabilization of functional transition metal centers can be realized by embedding them in a coordination environment of an organic backbone. Then, realizing twodimensional materials with improved stability and novel properties is possible through the careful design of the organic backbone. An understanding of the changes induced by the transition from isolated transition metal-organic complexes to their extended structures has been defined as the subject of this work. Thereby, transition metal-containing covalent networks and metal-organic frameworks have been realized. Starting from nickel tetraphenylporphyrin polymers, the emergence of π-delocalization in the molecular backbone as a consequence of polymerization has been confirmed by the appearance of energy-dispersive electronic valence states. This is quite surprising since the polymers have been determined to be amorphous by scanning tunneling microscopy measurements. Simultaneously, a defined functionality of the nickel centers has been observed during spectroscopic characterization. The two-dimensional nickel-containing polymers can be tuned by the reactivity of the surface used for their stabilization. Though indicated by the results obtained via theoretical modeling, the energy-dispersive nature of the nickel 3d-based valence states has turned out as experimentally not accessible. To mimic the functional center of nickel tetraphenylporphyrin, the transition from nickel 1,2,4,5-tetracyanobenzene complexes to two-dimensional  metal-organic framework has been realized. Thereby, the energy level alignment can be adjusted to enable experimental access to the nickel 3dbased valence states. The appearance of π-conjugation for the nickel 3d-based valence states upon formation of the polymeric structure has been clearly confirmed following the same multi-technique approach applied for the characterization of covalent nickel tetraphenylporphyrin networks.
%F PUB:(DE-HGF)3 ; PUB:(DE-HGF)11
%9 BookDissertation / PhD Thesis
%R 10.34734/FZJ-2024-06132
%U https://juser.fz-juelich.de/record/1032293