Polydiacetylenstabilisierte Goldnanopartikel als Bausteine für die Molekularelektronik

Gold nanoparticles (AuNP) show unique size-dependent physical and chemical properties. Their size, shape and surface functionalization can be easily modified by adjusting the synthetic procedure or by using specific stabilizing molecules. One parameter influencing the particles’ stability is therefore, the ligand molecule. In the present work, tailor-made ligand molecules were used to enable a cross-linkage of the ligand sphere on the AuNP surface to increase the stability. In order to realize a surface polymerization, diacetylene units within the molecular structure were used. They polymerize upon thermal treatment or ultraviolet (UV)-irradiation to build up so-called polydiacetylenes (PDA). Those DA units were integrated into the molecular scaffold, bound to the AuNP’s surface and subsequently polymerized. For applications in molecular electronics ligand molecules stabilizing AuNP have to fulfill certain requirements. It was elucidated, if these requirements were in coincidence with the ones needed for a successful polymerization. Therefore, a possible stability enhancement as well as the electrical transport characteristics of the AuNP were investigated. Taking the above mentioned considerations into account, the work emphasizes on four points. The first one covers the design and synthesis of the corresponding ligand molecules and their characterization. To gain an insight in the polymerization behavior, polymerization of those molecules was first investigated without AuNP. The next key aspect was the functionalization of AuNP and the characterization of this polymer metal hybrid system. The stability of those functionalized AuNP was investigated directly dependent on the polymerization condition. Those experiments revealed a limitation in stability enhancement. The fourth part covers some application-oriented experiments, which were performed with the functionalized AuNP. The electrical transport characteristics of a nanoelectrode device in which AuNP were integrated showed a nonlinear dependency of current on voltage. It could be described with a tunneling mechanism. Moreover, the possibility to remove the gold core via etching reaction was investigated to keep the ligand sphere as a hollow polymeric nanosphere. The adsorption behavior of nitrile terminated functionalized AuNP on possible electrode materials was also subject of investigation. Moreover, since nitrile groups are able to undergo complexation reactions, the complexation of the nitrile AuNP with a ruthenium complex was performed