Ruthenium-Terpyridine auf Goldoberflächen und Goldnanopartikeln für Anwendungen in der Nanoelektronik

  • Ruthenium Terpyridines on Gold Surfaces and Gold Nanoparticles for Applications in Nano-Electronics

Peter, Sophia Katharina; Simon, Ulrich (Thesis advisor); Oppel, Iris Marga (Thesis advisor)

Aachen (2020)
Dissertation / PhD Thesis

Dissertation, RWTH Aachen University, 2020

Abstract

Ruthenium terpyridines (Ru TP) are thanks to their linear structure and their high intensely studied complexes. Their application in nanoelectronics promises enormous potential, as the delocalized electron system offers conductivity, while the redox-active ruthenium centre enables electrical switching. In this thesis different methods to functionalize gold surfaces and gold nanoparticles (AuNP) have been investigated. In the first part of this thesis the syntheses and the characterization of the TP and Ru TP are discussed. The pH-dependent configuration change of the TP ligands could be shown. Further the syntheses and characterization of two new Ru TP complexes was proven using NMR, UV/VIS, IR and Raman spectroscopy, as well as mass spectrometry (MS). By stimulation the metal-ligand charge-transfer transition of the Ru-TP complexes resonant Raman spectra were also recorded. In the second part Ru-TP-wire were growth on Au surfaces in a stepwise approach. This approach was monitored via different surface sensitive methods, namely infrared-reflection-adsorption-spectroscopy and surface enhanced Raman spectroscopy and further followed by variable angle spectroscopic ellipsometry (VASE). To support the resulting spectra DFT calculation were performed and solid phase spectra of model substances recorded. By comparing those spectra and calculation of the dipole derivative unit vector the orientation of the molecules could be deduced. Through this the repetition count to bridge a two nanoelectrodes could be calculated and the suitability of those Ru TP wires could be tested. In the third part of this thesis synthesis conditions for the functionalization of AuNP with TP and Ru TP were found. The TP AuNP and Ru TP AuNP-hybrid systems were studied by means of UV/Vis, DLS, as well as Raman spectroscopy with two excitation wavelengths. Further TEM at high magnification were recorded to measure the distance between the AuNP. The DLS and TEM data indicate an increasing rising ligand layer thickness with increasing number of TP groups, while the UV/Vis date were found to be ambiguous due to solvent effects. Besides isotropically functionalized AuNP Janus-AuNP with TP and Ru TP ligands were synthesized, as well. Both ligands could be identified by measuring Raman at two excitation wavelengths. The distribution of TP and Ru TP could be determined using ICP-MS (induced coupled plasma MS). Further the coverage density and the footprint of all synthesized AuNP was determined through ICP MS. Moreover, the electrical properties of isotropic TP and Ru TP could already be investigated.

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