Softlithographische Methoden und deren Anwendung in der Katalysatorforschung und Mikrosystemtechnik

The aim of the first part of the thesis was the deposition of metallic contacts onto organic monolayers. The goal of these studies was the contacting of organic materials for their use in organic field-effect transistors (OFETs). Self-assembled monolayers are a good model system for surfaces of organic substances and may also be used in OFETs. To improve the contact, the monolayers should carry donor-head groups that can interact coordinatively with the metal. Based on chemical processes taking place at or just above RT, extensive studies concerning different deposition methods have been performed based on micro-contact printing (µCP) of nanoparticles (NP) as structuring principle. The patterns obtained this way should be amplified using either chemical gas phase deposition (CVD) or electroless deposition (ELD) of gold. CVD turned out not to be a suitable method for the selective deposition of gold when gold NP were used. Better results have been obtained using the ELD of gold. Several deposition baths with different reducing agents have been tested. Only one bath based on a concentrated hydroxylamine hydrochlorid solution led to satisfying and selective depositions. The gold source also has an influence on the quality of the deposited gold layers: baths containing tetrachloroauric acid lead to rough layers whereas sodium goldsulfite provides satisfying results with thicknesses up to 800 nm. Furthermore, the deposition is influenced by the exposed head groups of the SAMs as well as the stabilising ligands of the NP. A combination of N-terminated SAMs with 2-(2-mercaptoethoxy)ethanol stabilised gold NP turned out to be ideal to deposit thick and selective gold layers. The main goal of this work was the fabrication of combinatorial cyclovoltammetric (CV) microsensor arrays using µCP. Therefore, arrays consisting of 16 sensor fields containing interdigitating working and counter electrodes as well as an integrated Pb/PbHPO4 thin-film reference electrode have been fabricated. With these arrays, the catalytic oxidation of 2,6-di-tert-butyl-phenol (tBuPhe) and 2,3,6-trimethylphenol (MePhe) to the respective benzoquinones has been followed via CV as these benzoquinones are electrochemical active. The quantitative measurement was carried out by the time depended determination of the increase of the peak intensities. As catalysts, a library of diverse salen(type) complexes was used. 98 ligands have been prepared. For the catalytic reactions three different approaches have been investigated: First, salen ligands were prepared and isolated. For catalysis, they have been mixed with the respective electrolytes as well as the metal salt (cobalt(II) acetate) and the phenole. These mixtures were exposed to dioxygen for 24 hours and the respective conversions were measured electrochemically. It could be shown that, under these conditions, the oxidation of tBuPhe occurs under massive formation of a side-product, which covers the electrodes thus affecting the measurements. Ligands with more than two C-atoms between the N-atoms of the amine turned out to be unsuitable. In addition, it turned out that the catalyst/substrate proportion has a non-systematical influence: While in the case of tBuPhe a reduction of the proportion from 1:50 to 1:10 brings a decline, the reaction of MePhe has higher conversions in the case of a 1:10 ratio. By increasing the temperature, conversions of 99% can be obtained with both phenols. These results have been extended to preparative scales (catalyst/starting material ratio 1:500 with simultaneous increase of the educt concentration). The second approach was the ex situ performance of the catalysis in 96-well plates made of PTFE. Reaction conditions were the same as for the previous CV measurements, but with the conversion being only detected after 24 hours. An advantage was the high throughput for many different metal complexes. Apart from Co, Mn, Fe, Cu, Pd, W, Mo, and V have been used. At most stoichiometric conversions could be obtained. In conclusion, it could be shown that the oxidation of phenols depends on different criteria such as temperature and concentration as well as the starting material and the catalyst. Complexes that show high conversions for tBuPhe (educt/catalys ratio 50:1) also work with MePhe, although no exact correlation exists, making a new study for each new substrate necessary. For the two systems presented in this thesis, catalysts could be identified that show higher conversions than the previously used, non-substituted Co-salen complex.